JP3772710B2 - Optical disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus, and more particularly to optimization of power when recording data on a recordable optical disc.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a technique (OPC) for optimizing recording power by recording test data in a predetermined area (PCA area) of a recordable optical disc, reproducing the test data, and evaluating the signal quality is known. ing.
[0003]
However, there are cases where the recording power at which the reproduction signal quality reaches the optimum value exceeds the maximum allowable power of the LD due to temperature changes in the optical disk drive or variations in the laser diode (LD). In other words, recording cannot be performed with the optimum recording power, and recording must be performed with the maximum allowable power of the LD smaller than the optimum power.
[0004]
Therefore, for example, in Japanese Patent Laid-Open No. 9-288827, when the optimum recording power exceeds the maximum allowable power of the LD when OPC is performed, the recording quality is maintained by adjusting the number of revolutions of the optical disk at the time of data recording. Is described. Specifically, when the optimum recording power obtained by OPC exceeds the maximum allowable power of the LD,
[Expression 1]
f ′ = f · (Plim / Po) ²
The rotation speed is corrected to be small. Here, f ′ is the rotation speed after adjustment, f is the normal rotation speed before adjustment, Plim is the maximum allowable power, and Po is the optimum power. By reducing the rotational speed in this way, data can be recorded with the optimum power matched to the maximum allowable power.
[0005]
[Problems to be solved by the invention]
However, it is generally difficult to control the rotational speed with high accuracy. In addition, a decrease in rotational speed causes a decrease in recording speed, making it difficult to satisfy the demand for high-speed recording.
[0006]
On the other hand, in Japanese Patent Laid-Open No. 2001-143263, when a recording pulse is composed of a leading pulse and a succeeding pulse train, OPC is performed by changing the duty of the leading pulse and the succeeding pulse and the recording power condition at the same time, and jitter is reduced. Although a technique for searching for the minimum recording condition is described, it is basically necessary to perform test recording for the number of combinations of three parameters, and there is a problem that the OPC processing becomes complicated.
[0007]
The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is that the optimum recording power exceeds the maximum allowable power of the LD due to the temperature of the optical disk drive or the variation of the LD. It is another object of the present invention to provide an optical disc apparatus capable of easily recording data without causing a decrease in recording speed.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is an optical disc apparatus that performs test recording by changing the recording power in a predetermined area of the optical disc, and determines the optimum recording power based on the reproduction signal quality of the test recording data, the recording strategy is fixed to the first recording strategy, and means for determining whether the optimum recording power obtained when test recording exceeds the allowable recording power by using the first recording strategy, the optimum recording power When it is determined that the allowable recording power is not exceeded, the first recording strategy is maintained as it is, and only when it is determined that the allowable recording power is exceeded , the recording strategy is changed to a second recording strategy different from the first recording strategy and optimal recording is performed. And means for determining power again .
[0009]
Here, it is preferable that the second recording strategy is a recording strategy that requires less recording power than the first recording strategy. In this case, the second recording strategy may be a recording strategy having a recording pulse time width larger than that of the first recording strategy. Further, the second recording strategy may be obtained by increasing a recording pulse time width of the first recording strategy based on a difference between the optimum recording power and the allowable recording power.
[0010]
The present invention also provides an optical disc apparatus that performs test recording by changing recording power in a predetermined area of an optical disc, and determines an optimum recording power based on a reproduction signal quality of the test recording data, the reference strategy and the reference strategy Means for performing test recording using a low power strategy having a required recording power less than the above, means for evaluating the reference strategy and reproduction signal quality of test recording data by the low power strategy, and the test record data by the reference strategy Means for calculating a first optimum recording power based on reproduction signal quality; means for calculating a second optimum recording power based on the reproduction signal quality of test recording data by the low power strategy; and the first optimum recording power. Is less than the allowable recording power, the first optimum recording power is Determining the proper recording power, when the first optimum recording power exceeds the allowable recording power is characterized by having a means for determining the optimum recording power the second optimum recording power.
[0011]
The present invention also relates to an optical disc apparatus that performs test recording by changing the recording power in a predetermined area of the optical disc, and determines the optimum recording power based on the reproduction signal quality of the test recording data, and uses the reference strategy to perform the test. Means for recording, means for evaluating the reproduction signal quality of the test recording data according to the reference strategy, means for calculating a temporary optimum recording power based on the reproduction signal quality of the test recording data according to the reference strategy, and the temporary If the optimum recording power is less than or equal to the allowable recording power, the test recording is continued using the reference strategy to determine the optimum recording power. If the temporary optimum recording power exceeds the allowable recording power, the reference recording is performed. Continue the test recording using a low power strategy that requires less recording power than the strategy and And having a means for determining a power.
[0012]
The low power strategy may be a strategy having a larger recording pulse time width than the reference strategy.
[0013]
As described above, in the optical disc apparatus according to the present invention, when the optimum recording power is calculated with a certain recording strategy (first strategy or reference strategy), when the recording power exceeds the maximum permissible power of the optical disc apparatus, The optimum recording power is reduced by switching to this recording strategy. Thereby, it is possible to maintain the recording quality without performing processing such as recording with a power other than the optimum recording power as in the past or selecting the optimum combination from the possible combinations.
[0014]
The parameters that define the recording strategy include a recording pulse time width, a duty, and the number of pulses in the case of multi-pulses. For example, the required power can be reduced by increasing the pulse time width. Of course, the recording strategy can be set by adjusting other parameters that can reduce the necessary power.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
<First Embodiment>
FIG. 1 shows a block diagram of a main part of the optical disc apparatus according to the present embodiment. The optical disk 10 is CAV or CLV controlled by the spindle motor 12.
[0017]
The optical pickup unit 14 is provided facing the optical disc 10 and records data on the optical disc 10 by emitting laser light having a recording power from a laser diode (LD). Data recording may be performed by melting and sublimating a part of the recording film of the optical disc 10 to form pits, or by heating and quenching the crystalline state to transition to the amorphous state.
[0018]
At the time of data recording, the recording data is supplied to the encoder 18, and the data encoded by the encoder 18 is supplied to the LD driving unit 16. The LD drive unit 16 creates a drive signal based on the encoded data and supplies it to the LD of the optical pickup unit 14. The LD driving unit 16 is supplied with a control signal from the control unit 24, and the recording strategy and the recording power are determined by the control signal.
[0019]
On the other hand, at the time of data reproduction, the LD of the optical pickup unit 14 irradiates a laser beam having a reproduction power (reproduction power <recording power), receives the reflected light and converts it into an electric signal to obtain a reproduction RF signal. The reproduction RF signal is supplied to the reproduction RF signal processing unit 20.
The RF signal processing unit 20 includes an amplification amplifier, an equalizer, a binarization unit, a PLL unit, and the like, binarizes the reproduced RF signal, generates a synchronization clock, and supplies it to the decoder 22. The decoder 22 decodes data based on these supplied signals and outputs it as reproduced data.
[0020]
The reproduced RF signal from the RF signal processing unit 20 is also supplied to the control unit 24 for signal quality evaluation. At the time of data reproduction, a tracking error signal and a focus error signal are also generated to control the focus servo or tracking servo, and a wobble signal formed on the optical disk 10 is reproduced and used for address demodulation or rotation speed control. There are also circuits, but these are the same as in the prior art, so the description thereof is omitted.
[0021]
The control unit 24 drives the LD driving unit 16 to execute OPC, evaluates the signal quality of each test recording data, and determines the optimum recording power. At this time, the control unit 24 performs OPC with a predetermined recording strategy to calculate the optimum power. If the optimum power is less than or equal to the maximum allowable power of the LD, recording is performed using the recording strategy and the optimum power at that time, and the recording strategy is changed only when the optimum power exceeds the maximum allowable power of the LD. And search for the optimum power again. By changing the recording strategy only when the optimum power exceeds the maximum allowable power, it is possible to perform high-quality data recording while simplifying the OPC process.
[0022]
The optical disc apparatus of the present embodiment has the above-described configuration, and the optimum recording power determination process in the control unit 24 will be described in detail below.
[0023]
FIG. 2 shows a process flowchart of the control unit 24. First, the control unit 24 reads a disc ID written in advance in a predetermined area of the optical disc 10 based on a read signal from the optical pickup unit 14 and determines the type of the optical disc 10. The type of the optical disk 10 is a distinction between CD-R, RW, DVD-R, etc., and a manufacturer. In the present embodiment, a case of DVD-R will be described as an example. When recording conditions, for example, a reproduction signal quality target value is written, these conditions are also reproduced and stored in the memory of the control unit 24. As the target value, the beta value (β value) of the reproduction signal is used in this embodiment.
[0024]
After determining the type of the optical disc 10, the control unit 24 sets a recording strategy for recording data (S102). The recording strategy is a recording LD drive pulse for forming a pit having a desired size and shape. In the present embodiment, the recording strategy is not selected from many combinations, but is a reference strategy. Str and low power strategy Stl are set. The reference strategy Str is determined from the disk ID read in S101, and the low power strategy Stl is obtained by correcting this reference strategy Str.
[0025]
FIG. 3 shows a part of the strategy setting in S102. In the figure, (a) is a recording pulse supplied from an encoder and includes, for example, a 3T signal and a 4T signal. (B) is a reference recording strategy Str, and 3T → 1.5T for 3T and 4T, respectively.
4T → 1.5T + 0.6T
The LD is driven by such a pulse signal to record data. In 3T, a single pulse is used, but in 4T, data is recorded with a plurality of pulses (multi-pulse). The time width of the first pulse of the multi-pulse is 1.5T, and the time width of the subsequent pulse is 0.6T. In this example, data is recorded with two pulses as 4T, but the same applies to a signal with 5T or more, in which data can be recorded with three or more multipulses as required. This reference strategy is generally an optimal strategy that is set for each type or manufacturer of the optical disc 10.
[0026]
On the other hand, (c) shows a recording strategy Sts for low power, and 1.5T → 1.6T for the 3T signal with respect to the reference recording strategy Str.
For the 4T signal, the leading pulse is
1.5T → 1.6T
And the time width has increased with respect to the reference strategy. By increasing the time width in this way, more laser beam energy can be applied to the optical disk 10, and therefore, the recording power for forming the same pit can be reduced. “Low power strategy” means that the recording power of the LD required for forming the same pit is lower than that of the reference strategy. In order to obtain a low power strategy, the time width of the reference strategy may be increased as described above. However, the increase amount may be a predetermined amount, or may be appropriately adjusted as described later.
[0027]
Returning again to FIG. 2, after setting the reference strategy Str and the low power strategy Stl as described above, the control unit 24 performs test recording using the reference strategy Str and the low power strategy Stl (S103). For example, when there are 16 sectors in the PCA area of the optical disk 10, the test recording can be performed by recording the first 8 sectors with the reference strategy Str and the remaining 8 sectors with the low power strategy Stl.
[0028]
After performing test recording by changing the recording power with each of the two strategies Str and St1, the reproduction RF signal of each test recording data is input from the RF signal processing unit 20, and the β value is measured as the reproduction signal quality in each strategy. (S104). The β value is calculated from the peak level A1 and the bottom level A2 in the waveform when the reproduction RF signal is AC-coupled (signal with the DC component cut off)
β = (| A1 | − | A2 |) / (| A1 | + | A2 |)
Is calculated by β increases monotonically according to the recording power. The control unit 24 calculates β of the reference strategy Str and β of the low power strategy Stl for each recording power according to the above formula.
[0029]
Then, in each strategy, the optimum recording power for obtaining the target value β0 stored in the memory of the control unit 24 is calculated for each strategy (S105). The optimum recording power can be calculated by plotting the β value for each recording power and calculating the recording power for obtaining the target value β0 (for example, 0.04) by linear approximation or extrapolation. The optimum recording power for the reference strategy Str is Ptr, and the optimum recording power for the low power strategy Stl is Ptl. When the time width of the recording pulse increases, the necessary power decreases accordingly, so that Ptr> Ptl.
[0030]
FIG. 4 shows how the optimum recording power Ptr is calculated in the reference strategy Str. In the figure, the horizontal axis represents the recording power under the reference strategy Str, and the vertical axis represents the β value of the reproduction RF signal. It shows that the optimum recording power Ptr for obtaining the target value β0 is calculated by extrapolation.
[0031]
After calculating the optimum recording power for each strategy, the control unit 24 compares the maximum allowable power Plim of the LD previously recorded in the memory of the control unit 24 with the optimum recording power Ptr for the reference strategy (S106). The maximum allowable power Plim may be the maximum power that can be output by the LD, but may be set to a power lower by a predetermined amount than the maximum power in consideration of the margin. If the optimum recording power Ptr of the reference strategy is equal to or less than the maximum allowable power Plim (YES in S106), it is determined that data can be recorded as it is, the recording strategy remains as the reference strategy Str, and the optimum recording power is set. Data is recorded on the optical disc 10 as Ptr (S107).
[0032]
On the other hand, if the optimum recording power Ptr exceeds the maximum allowable power Plim in S106, data cannot be recorded under this condition, so the control unit 24 determines the low power strategy Stl set in S102 as the recording strategy, and The optimum recording power is determined as Ptl calculated in S105, and data is recorded on the optical disc 10 (S108). Ptl is smaller than Ptr, and Ptl can be reduced to Plim or less by appropriately setting the low power strategy Stl. Therefore, recording data with Ptl enables high-quality data recording without reducing the recording speed. It can be carried out.
[0033]
In this embodiment, the low power recording strategy is created by increasing the pulse time width of the reference strategy. However, in the multi-pulse shown in FIG. 5, in addition to increasing the time width T1 of the leading pulse, A low power strategy can be obtained by increasing the number C of pulses, changing the duty of a multi-pulse, or changing both the time width T1 and the duty.
[0034]
Further, in order to shape the pit shape into a desired shape, a recording strategy that boosts the recording power at the initial stage of the recording pulse as shown in FIG. 6 may be used (in the figure, not a multi-pulse, It is assumed that a single pulse is used as in the case of CD-R, and a similar boost pulse can be used for multiple pulses). In such a strategy, in order to set a low power strategy, it is also preferable to increase the boost period T2 with respect to the reference strategy.
[0035]
Second Embodiment
7 and 8 show processing flowcharts of the control unit 24 in the present embodiment. The basic configuration is the same as in FIG.
[0036]
First, the control unit 24 reads the ID of the optical disc 10 and determines the type of the optical disc 10 (S201). After determining the type of the optical disc 10, the control unit 24 sets a recording strategy (S202). As a recording strategy, a reference strategy Str and a low power strategy Stl are set as in the first embodiment.
[0037]
After setting the two recording strategies, test recording is performed with the reference strategy Str using only 4 sectors out of 16 sectors in the PCA area (S203). Note that the test recording is performed in only 4 sectors out of 16 sectors, but the optimum recording power is not obtained here, but the optimum recording power is roughly determined, and the provisional optimum recording power is set to the maximum allowable power. This is because it is determined whether or not it exceeds. Therefore, it is sufficient to use only the number of sectors sufficient to obtain the optimum recording power. For example, 3 sectors or 5 sectors may be used. The number of sectors is arbitrary. After performing test recording (recording with varying recording power) using the reference strategy Str in only four sectors, the β value based on the reference strategy is measured from the reproduced RF signal. Based on the relationship between the recording power and the β value, the optimum recording power Pp for obtaining the predetermined target value β0 is calculated (S205). Note that, unlike the first embodiment, in this embodiment, test recording is executed only by the reference strategy, and test recording by the low power strategy is not executed at this stage.
[0038]
After calculating the provisional optimum recording power Pp based on the reference strategy, the control unit 24 compares the predetermined maximum allowable power Plim with the provisional optimum recording power Pp (S206). If the provisional optimum recording power Pp is less than or equal to the maximum allowable power Plim, it is determined that there is no problem even if recording is performed with the reference strategy Str, the recording strategy is determined to be Str (S207), and test recording is performed out of 16 sectors in the PCA area. The true optimum recording power is calculated using the remaining 12 sectors. That is, test recording is continued using 12 sectors (S208), β at each recording power is calculated (S209), and the recording power Ptr that becomes the target value β0 is determined as the optimum recording power (S210). In this case, test recording with a low power strategy is not performed at all, and the OPC process is simplified.
[0039]
On the other hand, if the provisional optimum recording power Pp exceeds the maximum allowable power Plim, the recording strategy is determined to be the low power strategy St1 as shown in FIG. 8 (S211), and the remaining 12 sectors of the 16 sectors in the PCA area. Then, test recording is performed with the low power strategy St1 (S212), β at each recording power is calculated (S213), and Ptl which is the target value β0 is calculated (S214). Then, this Ptl is adopted as the optimum recording power, and data is recorded on the optical disc 10.
[0040]
As described above, in the present embodiment, test recording is first performed using only the reference strategy, and the test using the low power strategy Stl is performed only when the optimum recording power based on the test recording (temporary optimum recording power) exceeds the maximum allowable power. Since recording is performed, processing is simplified.
[0041]
<Third Embodiment>
FIG. 9 shows a process flowchart of the control unit 24 in the present embodiment. The basic configuration is the same as in FIG.
[0042]
In this embodiment, the difference from the second embodiment described above is that the control unit 24 does not use a fixed low power strategy but adaptively sets it. That is, in the second embodiment, the low power strategy Stl is set in advance with respect to the reference strategy Str, but in this embodiment, the provisional optimum recording power Pp obtained by performing test recording with the reference strategy is When the maximum allowable power Plim is exceeded, the low power strategy Stl is set according to the difference amount (Plim−Pp) between the maximum allowable power Plim and the provisional optimum recording power Pp (S308). There are various methods for setting according to the difference amount (Plim-Pp). For example, as shown in FIG. 10, the time width of the recording pulse with respect to the reference strategy is increased in proportion to the difference amount (Plim-Pp). For example, a large amount Δt is increased.
[0043]
By increasing Δt and increasing the recording pulse width as the difference amount (Plim−Pp) increases, optimization can be performed with less power. It is also possible to increase the time width according to the ratio Pp / Plim of both instead of the difference amount (Plim−Pp).
[0044]
As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various change is possible. For example, in the present embodiment, one strategy Stl is set as the low power strategy, but two or more are set as the low power strategies, and the optimum recording power corresponding to these strategies is less than the maximum allowable power Plim. It is also preferable to select the one having the largest power or the largest margin. However, if a large number of strategies are facilitated as a low power strategy, the OPC process is complicated accordingly, so several low power strategies may be suitable.
[0045]
Further, although the strategy corresponding to the disk ID read from the optical disk 10 is used as the reference strategy, a strategy corrected by a predetermined amount with respect to the strategy determined from the disk ID can be set as the reference strategy. When data is recorded on each of the land and the groove of the optical disc 10, a reference strategy and a low power strategy can be set for each of the land and the groove, and the recording power and the recording strategy can be determined for each. In this case, the target β0 for calculating the optimum recording power may be a value different between the land and the groove.
[0046]
In this embodiment, the β value is used as the reproduction signal quality. However, the present invention is not limited to this, and evaluation may be performed using a jitter or an error rate.
[0047]
In this embodiment, the target β value for calculating the optimum recording power in the reference strategy and the target β value for calculating the optimum recording power in the low power strategy are the same, but the target β value is set according to the strategy. It may be changed.
[0048]
In this embodiment, the DVD-R has been described as an example. However, the present invention can be similarly applied to a CD-R or a CD-RW. In this case, it is possible to use a low power recording strategy in which each pulse time width is increased with respect to a reference strategy having a pulse length corresponding to the length 3T to 11T of data to be recorded.
[0049]
Furthermore, although OPC is performed in units of sectors in this embodiment, OPC can be performed by changing the recording power in units of prepits.
[0050]
【The invention's effect】
As described above, according to the present invention, high-quality data recording can be performed regardless of variations in temperature and LD in the optical disk drive and without reducing the recording speed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment.
FIG. 2 is a process flowchart of a control unit in the first embodiment.
FIG. 3 is an explanatory diagram showing a relationship between a reference strategy and a low power strategy.
FIG. 4 is a graph showing the relationship between recording power and β value.
FIG. 5 is an explanatory diagram of another low power strategy.
FIG. 6 is an explanatory diagram of still another low power strategy.
FIG. 7 is a process flowchart (No. 1) of a control unit in the second embodiment.
FIG. 8 is a process flowchart (No. 2) of the control unit in the second embodiment.
FIG. 9 is a processing flowchart of a control unit in the third embodiment.
FIG. 10 is a graph showing a relationship between a difference amount Plim−Pp and a time width increase amount Δt.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Optical disk, 12 Spindle motor, 14 Optical pick-up part, 16LD drive part, 18 Encoder, 20 RF signal processing part, 22 Decoder, 24 Control part.

Claims (7)

An optical disc apparatus that performs test recording by changing a recording power in a predetermined area of an optical disc, and determines an optimum recording power based on a reproduction signal quality of the test recording data,
Means for fixing the recording strategy to the first recording strategy and determining whether or not the optimum recording power obtained when performing test recording using the first recording strategy exceeds an allowable recording power;
The optimum recording power is permitted not to exceed the recording power and the first recording strategy when it is determined as to maintain, exceeds determined as the first only while maintaining the recording speed when recording strategy different from the second Means for changing the recording strategy to the recording strategy and determining the optimum recording power again;
An optical disc apparatus comprising: The apparatus of claim 1.
The optical disc apparatus characterized in that the second recording strategy is a recording strategy that requires less recording power than the first recording strategy. The apparatus of claim 2.
2. The optical disc apparatus according to claim 1, wherein the second recording strategy is a recording strategy having a recording pulse time width larger than that of the first recording strategy. The apparatus of claim 2.
The optical disc apparatus characterized in that the second recording strategy is obtained by increasing a recording pulse time width of the first recording strategy based on a difference between the optimum recording power and the allowable recording power. An optical disc apparatus that performs test recording by changing a recording power in a predetermined area of an optical disc, and determines an optimum recording power based on a reproduction signal quality of the test recording data,
Means for performing test recording using a low power strategy having a required recording power less than that of the reference strategy at the same recording speed as the reference strategy;
Means for evaluating the reproduction signal quality of test recording data according to the reference strategy and the low power strategy;
Means for calculating a first optimum recording power based on the reproduction signal quality of the test recording data according to the reference strategy;
Means for calculating a second optimum recording power based on the reproduction signal quality of the test recording data by the low power strategy;
When the first optimum recording power is less than or equal to the allowable recording power, the first optimum recording power is determined as the optimum recording power, and when the first optimum recording power exceeds the allowable recording power, the second optimum recording power is determined. Means for determining the power to the optimum recording power;
An optical disc apparatus comprising: An optical disc apparatus that performs test recording by changing a recording power in a predetermined area of an optical disc, and determines an optimum recording power based on a reproduction signal quality of the test recording data,
Means for recording a test using a reference strategy;
Means for evaluating the reproduction signal quality of the test recording data according to the reference strategy;
Means for calculating a provisional optimum recording power based on the reproduction signal quality of the test recording data according to the reference strategy;
When the provisional optimum recording power is less than or equal to the allowable recording power, the test recording is continued using the reference strategy to determine the optimum recording power, and when the provisional optimum recording power exceeds the allowable recording power. Means for determining the optimum recording power by continuing the test recording using a low power strategy that requires less recording power than the reference strategy at the same recording speed ;
An optical disc apparatus comprising: The device according to any one of claims 5 and 6,
The optical disc apparatus characterized in that the low power strategy is a strategy having a recording pulse time width larger than that of the reference strategy.

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