JP4609774B2 - 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 disc recording / reproducing apparatus, an optical disc recording / reproducing method, and an optical disc recording / reproducing program, and in particular, when recording with a laser beam on a rewritable disc optical recording medium (optical disc) having a plurality of recording layers. The present invention relates to an optical disc recording / reproducing apparatus, an optical disc recording / reproducing method, and an optical disc recording / reproducing program for recording and reproducing a test recording signal and detecting an optimum recording power condition and then recording and reproducing user data under the optimum recording power condition.

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, a DVD-R disc having two recording layers, D
Development of VD-RW discs is ongoing. FIG. 15 shows this dual-layer DVD-R disk, 2
1 shows a schematic structural cross-sectional view of an example of a layered DVD-RW disc. As shown in the figure, a single-sided dual-layer DVD-R disc or DVD-RW disc has a first recording layer 301 and a second recording layer 3.
02 are stacked in the optical axis direction of the light beam 402 at the time of recording / reproducing, and the light beam 402 is condensed on the first recording layer 301 by the objective lens 401 in the optical pickup or the first recording layer The light passes through 301 and is condensed on the second recording layer 302.

The recording area of the first recording layer 301 closer to the optical pickup is composed of a PCA area (Power Calibration Area) 311 and an RMA area (Recording Manage) from the inner circumference toward the outer circumference.
ment Area) 312, lead-in area (Lead-In) 313, data area (Data Area) 31
4 and a middle area 315.
The recording area of the second recording layer 302 is a PCA area 3 from the inner periphery toward the outer periphery.
21, RMA area 322, lead-out area (Lead-Out) 323, data area (Data Are
a) It is divided into 324 and a 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.
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. Lead-in area 313
A part of the disk has an area called the control data zone, which contains information on the entire disk such as the size of the disk and reference conditions for recording such as the recording power, recording waveform pattern, and erasing power ratio. Pre-pit data information is recorded in advance at the time of 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 the first recording layer 301.
And the second recording layer 302 have different thicknesses, and even in the same optical disc, the optimum power may differ depending on the pulse strategy at the time of writing, the difference in the laser waveform, etc., and it is necessary to obtain the optimum recording power by OPC. Become.

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. The value obtained by integrating and averaging the time divided by the clock period multiplied 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. 2mW, erase power is about ± 0.
It can be seen that the power setting error of the erasing 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. Manufacturers (even DVD-RWs)
The above margin is slightly different depending on (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. It is an object of the present invention to provide an optical disc recording / reproducing apparatus, an optical disc recording / reproducing method, and an optical disc recording / reproducing program that can detect the optimum recording conditions.

Therefore, in order to solve the above problems, the present invention provides the following apparatus, method, and program.
(1) In an optical disc recording / reproducing apparatus that performs recording / reproduction using a laser beam having a set power with respect to a rewritable optical disc having multiple recording layers,
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 setting a bias power for performing recording, and recording a test recording signal in a predetermined area of the optical disc by the laser beam using each of the set recording power, erasing power and bias power values;
DC erasure in which the area of the optical disk in which the test recording signal is recorded by the recording means is recorded by the laser beam with only the DC erasing power whose power value changes with the power related to the set erasing power as a central value. Means,
A recording state detecting means for reproducing a region recorded by the DC erasing means and detecting a γ value which is a parameter indicating a slope characteristic normalized from a modulation degree of the reproduced signal;
Determining means for determining a minimum value as a detected value for DC erasing power among values detected by the recording state detecting means from a plurality of areas having different DC erasing powers recorded by the DC erasing means; ,
The optimum erasing power value at the time of optical disc recording is obtained by multiplying the DC erasing power value recorded for the area where the detection value determined by the determining means is obtained by a coefficient determined in advance corresponding to the optical disc. Computing means for obtaining
An optical disc recording / reproducing apparatus characterized in that an optimum erasing power value at the time of optical disc recording is derived.
(2) In 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 plurality of recording layers,
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 A first step of recording a test recording signal in a predetermined area of the optical disc with the laser beam using the set values of the recording power, erasing power, and bias power.
The area of the optical disc on which the test recording signal is recorded in the first step is recorded with the laser light having only the DC erasing power whose power value changes with the power related to the set erasing power as a central value. A second step;
A third step of reproducing the area recorded in the second step and detecting a γ value which is a parameter indicating a slope characteristic normalized from the modulation degree of the reproduced signal;
4th which determines the minimum value as a detected value for DC erasing power among the values detected by the recording state detecting means from a plurality of areas having different DC erasing powers recorded in the second step. And the steps
The optimum erasing power at the time of optical disc recording is obtained by multiplying the DC erasing power value recorded in the area where the detection value determined in the fourth step is obtained by a coefficient determined in advance corresponding to the optical disc. A fifth step for determining the value of
An optical disc recording / reproducing method characterized in that an optimum erasing power value at the time of optical disc recording is derived.
(3) An optical disc recording / reproducing program for controlling recording / reproducing means for performing recording / reproducing with a laser beam on a rewritable optical disc having a plurality of recording layers by 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 The recording / reproducing means is configured to record a test recording signal in a predetermined area of the optical disc by the laser beam using the set values of the recording power, erasing power and bias power. A first step of indicating;
The area of the optical disc on which the test recording signal is recorded in the first step is recorded with the laser light having only the DC erasing power whose power value changes with the power related to the set erasing power as a central value. A second step of instructing the recording / reproducing means,
A third instruction for instructing the recording / reproducing means to reproduce the area recorded in the second step and detect a γ value that is a parameter indicating a slope characteristic normalized from the modulation degree of the reproduced signal. And the steps
The second recording was performed by step, DC erase power is fourth determining the minimum value as the detection value for the DC erasing power in value the third step detects from each of a plurality of different areas Steps,
The optimum erasing power at the time of optical disc recording is obtained by multiplying the DC erasing power value recorded in the area where the detection value determined in the fourth step is obtained by a coefficient determined in advance corresponding to the optical disc. A fifth step for determining the value of
An optical disc recording / reproducing program for causing a computer to execute

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. Γ value, which is a parameter indicating the slope characteristic, and a parameter (β
At least one of these values or asymmetry values), and the fact that the point at which the detection characteristic changes suddenly and the erasure is abruptly detected can be detected with little influence on the recording characteristic. By multiplying a predetermined coefficient on the basis of the above, it is possible to derive a highly accurate erasing power (an experimental result indicating that this error is high and the error is within 2% with respect to the optimum 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 on the optical disc 1 (disc structure, recommended recording power, recording strategy, recording power / erasing power ratio ε, etc.), and the internal bus 10 and the control circuit 11
And stored in the device memory 14. When recording data on the optical disc 1, the control circuit 1
1, write address, write power (recording power, erase power, bias power) and recording strategy setting information are transmitted to the recording means 6 through the internal bus 10 in the signal processing circuit 3. 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 ALPC (Automatic Laser Power Control) means (not shown) in the recording means 6.
Is controlled with high accuracy to the write power value set by. 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, DC
The erasing unit 5 multiplies the recommended recording power value (Pind) and the recording power / erase power ratio ε to calculate an optimum erasing power read from the optical disc 1 or the device memory 14. The DC erasing power value (= ε · Pind / S) close to the reference is obtained by calculation from the value of the coefficient (hereinafter referred to as the coefficient S), and the DC around the reference value is obtained.
Variable erase power value. 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. The optical disk recording / reproducing apparatus has the device memory 1 when a more reliable value is stored in the device memory 14 by the learning function or the control program update.
The value stored in 4 may be selected with priority.

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 is a predetermined value (modulation degree, γ value condition, asymmetry β value) determined in advance by a control program stored in the device memory 14.
And the measurement result of the detected recording state input from the signal processing circuit 3 are compared by the determination means 13 to determine the DC erasure area of the optical disc 1 showing the coincidence or the closest value, and
The value of the erase power performed in the DC erase area is obtained.

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 the signal A
1 and the signal A2 are calculated 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 showing the β value for asymmetry by varying the recording power. As a characteristic, the recording of the test recording signal to the first recording layer is performed once (initial) and twice (DOW1).
), And 11 times (DOW10), the peak position is in the vicinity of the same although there is a characteristic difference due to the difference in the number of repeated recordings. 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, among the pulses in FIG. 16A, the writing power (recording power) Pw and the bias power Pb are fixed at a fixed value, and the erasing power P
The characteristic diagram of the erasing power and the asymmetry β value when only e is recorded 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 1 in the OPC area of the first recording layer of the double-layer optical disc.
Times recording (initial), 2 times recording (DOW1), 11 times recording (DO
Each recording area of W10) is recorded with only the erasing power whose level is variable as shown in FIG. 2 (DC erasing), and then the asymmetry β value is detected from the reproduced RF signal obtained by reproducing the area. However, it can be seen that there is almost no difference in the recording characteristics depending on the number of repeated recordings, and the respective characteristics are almost the same.

Using this characteristic, the comparison determination circuit 110 in FIG. 3 (corresponding to a part of the determination means 13 in FIG. 1).
As a predetermined β value to be compared with the β value from the calculation means 107, for example, “−4” in FIG.
By using the value “0”, it is possible to detect the reference value of the erasing power with less 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, among the pulses in FIG. 16A, the writing power (recording power) Pw and the bias power Pb are fixed at a fixed value, and the erasing power P
The characteristics of erasing power and degree of modulation when only e is recorded are shown. 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 first recording (initial) and the second recording (DOW1).
) When the 11th (DOW10) and repeated areas were recorded with only erasing power and variable levels (DC erasing), there was a slight difference in recording characteristics depending on the number of repeated recordings. However, it can be seen that the respective characteristics are almost the same.

A predetermined modulation degree value (m value) to be compared by the comparison determination circuit 111 of FIG. 3 using this characteristic.
As a result, by using, for example, a value of “0.3” in FIG. 5D, it is possible to detect the reference value of the erasing power with a relatively 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. The PCA area recorded in advance for test recording is shown in FIG.
The DC erasing power as shown in FIG. 5 is recorded while being changed step by step, and the detection signal of the modulation degree m obtained from the recording state detecting means 4 by reproducing the same area is used as the DC erasing power for each step. The corresponding modulation degree m is stored in the device memory 14 of FIG. Then, as shown in FIG. 3, based on the data from the device memory 14, “a change amount of the modulation degree m from one step ahead (d
m) ”113,“ amount of change in erasing power one step ahead (dPe) ”114,“ value of modulation m in current step (m) ”115, and“ DC erasing in current step ” The power value (Pe) "116 is obtained.

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.

The recording power parameter γ (Pw) is not shown in FIG.
The calculation is similarly performed by replacing ~ 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, FIG.
The γ target (γtarget) is determined, the recording power (Ptarget) at which the detected γ characteristic coincides with this γ target is obtained, and this value is used as a reference value and multiplied by the coefficient ρ 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. Recording conditions (DO
This is because W1) can perform the best recording (minimum reproduction jitter).

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 is recorded for the first time (initial), the second time (DOW1), and the eleventh time (DOW10).
It can be seen that γ (Pe) does not change much depending on the erasing power even if it is repeated, and it cannot be used for detecting 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 DC erasing power corresponding to the peak apex is used as a reference value.
By multiplying by a coefficient Sg for obtaining a predetermined optimum erasing power, the optimum erasing power can be obtained. 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. this is,
As shown in FIG. 17, it is determined in view of the relatively poor reproduction jitter at the time of the second recording, so that 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). For measurement, three types of sample discs are used: RW 2 layers A and R
As the W2 layer B and the RW2 layer C, each optical disk is divided into four different recording devices (device A, device A,
Test recording was performed with the devices B, C, and D), and after 11 test recordings, DC erasure was performed (DOW10), a γ value was obtained from the residual amplitude of the recorded signal, and the DC erasing power reference from the peak point We are looking for a value. 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, a test recording signal to be recorded is a random pattern signal (EFM) of a recording waveform pattern.
Signal), recording strategy and write power (recording power Pw, erasing power Pe)
The test recording is performed in the OPC area (corresponding to 311 in FIG. 15) of the first recording layer of the double-layer optical disk 1 under a certain condition of the bias power Pb) (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. To 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. (B)
Since it is extremely narrow from FIG. 19, first, the optimum erasing power is precisely detected, and the recording power is obtained using ε from the obtained erasing power.
This is characterized in that the number of test recordings for the C process can be reduced, and the drive device startup time can be substantially shortened.

(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. Did the test recording area D
When the C erasing power is increased stepwise, the short mark is erased first, and the amplitude of the RF signal is attenuated. Therefore, it can be seen that the longer mark has a higher degree of disappearance.
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, the portion where the 14T signal is recorded once is varied step by step with the DC erasing power.
In the case of C erasure (initial), the portion where the 14T signal is repeatedly recorded a total of 2 times and the portion where the 14T signal is recorded while being repetitively stepped with the DC erasing power (DOW1), the portion where the 14T signal is recorded 11 times in total is recorded. When DC erasing is performed while varying stepwise with DC erasing power (DO
For each of W10), experimental results obtained by measuring the parameter γ (Pe) and the γ value that is a parameter indicating the normalized slope characteristic of the modulation degree are 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 is the longest mark signal of the recording mark of the recording waveform pattern or a long mark including the longest mark signal (for example, 8T to 14T in the case of 8/16 modulation signal).
Any mark signal) or a single long mark (eg 8T in the case of an 8/16 modulation signal)
It can be seen that good results can be obtained by performing test recording on the optical disk using any mark signal of 14T 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 erase power coefficient table is stored in the device memory 14.
Stored 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, and 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, when the set range of the coefficient Sg code is substituted into the above equation, the coefficient Sg is 1.
It can be determined as a value between 0 and 1.62.

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 cases, the characteristics of repeated recording (
It can be seen that the first recording, the first repetitive recording, and the tenth repetitive recording) 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, the optimum erasing power (Pe) is 5
Since the DC erasing power of the initialization process is about 9 mW to 14.5 mW (W in FIG. 10) that is slightly higher than the optimum erasing power (Pe), the dependency of repeated recording is high. It can be seen that a little state can be obtained. 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). Then, the PCA area of the first recording layer for performing OPC is 1 at 13 mW, which is about twice the optimum erasing power.
The result of having confirmed the characteristic about a modulation degree, (gamma) value, and asymmetry (beta) value after performing high-power initialization processing only once 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. 12A and 12B
) Shows a characteristic diagram of the DC erasing power and the modulation degree, and FIG. 12 (A) shows FIG. 12 (B) without initialization.
Indicates 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, DC erasing is performed by changing the DC erasing power in the area where the test recording signal is recorded once in the area within the PCA area of the first recording layer (initial).
When the DC recording power is varied and the DC erasing power is changed at the location where the test recording signal is recorded twice in total (DOW1), the DC recording power is changed at the location where the test recording signal is recorded 11 times in total by changing the DC erasing power. The experimental result which measured (beta) value or a modulation | alteration degree, or (gamma) value about each case (DOW10) erased is shown.

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. Note that FIG. 11B and FIG.
The characteristics of B) and FIG. 13B show a case where a dual-layer DVD-RW disc is used and a high power initialization process is performed at a disc rotational speed of 2 × 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 used from the beginning (Y),
The PCA area is initialized with a DC erase power approximately twice the calculated recommended erase power value (= ε · Pind) or optimum erase power (Pe) (step 503). Then, a flag is recorded in the recording management area (RMA area) as the high power initialization process has been completed (step 50).
5) 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. The recommended erasing power value (= ε · Pi) for only the OPC area to be used.
nd) or a high power initialization process in the PCA area with a DC erase power about twice the optimum erase power (Pe) (step 504), and 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 setting a bias power for performing recording, and recording a test recording signal in a predetermined area of the optical disc by the laser beam using each of the set recording power, erasing power and bias power values;
DC erasure in which the area of the optical disk in which the test recording signal is recorded by the recording means is recorded by the laser beam with only the DC erasing power whose power value changes with the power related to the set erasing power as a central value. Means,
A recording state detecting means for reproducing a region recorded by the DC erasing means and detecting a γ value which is a parameter indicating a slope characteristic normalized from a modulation degree of the reproduced signal;
Determining means for determining a minimum value as a detected value for DC erasing power among values detected by the recording state detecting means from a plurality of areas having different DC erasing powers recorded by the DC erasing means; ,
The optimum erasing power value at the time of optical disc recording is obtained by multiplying the DC erasing power value recorded for the area where the detection value determined by the determining means is obtained by a coefficient determined in advance corresponding to the optical disc. And calculating means for obtaining
An optical disc recording / reproducing apparatus characterized in that an optimum erasing power value at the time of optical disc recording 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-layered 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 A first step of recording a test recording signal in a predetermined area of the optical disc with the laser beam using the set values of the recording power, erasing power, and bias power.
The area of the optical disc on which the test recording signal is recorded in the first step is recorded with the laser light having only the DC erasing power whose power value changes with the power related to the set erasing power as a central value. A second step;
A third step of reproducing the area recorded in the second step and detecting a γ value which is a parameter indicating a slope characteristic normalized from the modulation degree of the reproduced signal;
4th which determines the minimum value as a detected value for DC erasing power among the values detected by the recording state detecting means from a plurality of areas having different DC erasing powers recorded in the second step. And the steps
The optimum erasing power at the time of optical disc recording is obtained by multiplying the DC erasing power value recorded in the area where the detection value determined in the fourth step is obtained by a coefficient determined in advance corresponding to the optical disc. A fifth step for determining the value of
An optical disc recording / reproducing method characterized in that an optimum erasing power value at the time of optical disc recording is derived. An optical disc recording / reproducing program for controlling, by a computer, recording / reproducing means for performing recording / reproducing with a laser beam 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 preventing thermal diffusion during recording to the recording layer The recording / reproducing means is configured to record a test recording signal in a predetermined area of the optical disc by the laser beam using the set values of the recording power, erasing power and bias power. A first step of indicating;
The area of the optical disc on which the test recording signal is recorded in the first step is recorded with the laser light having only the DC erasing power whose power value changes with the power related to the set erasing power as a central value. A second step of instructing the recording / reproducing means,
A third instruction for instructing the recording / reproducing means to reproduce the area recorded in the second step and detect a γ value that is a parameter indicating a slope characteristic normalized from the modulation degree of the reproduced signal. And the steps
The second recording was performed by step, DC erase power is fourth determining the minimum value as the detection value for the DC erasing power in value the third step detects from each of a plurality of different areas Steps,
The optimum erasing power at the time of optical disc recording is obtained by multiplying the DC erasing power value recorded in the area where the detection value determined in the fourth step is obtained by a coefficient determined in advance corresponding to the optical disc. A fifth step for determining the value of
An optical disc recording / reproducing program for causing a computer to execute

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