JP2825959B2 - Optical disk drive with optimal power setting - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device that irradiates a recording medium with a laser beam that is finely focused and optically records information.

2. Description of the Related Art An optical disk device is known as a device capable of irradiating a disk-shaped recording medium with laser light to record digital data and image signals. In the optical disk device, the peak power applied to the disk has a great effect on the quality of a recorded signal, and a method for recording at the optimum peak power on the disk is important. A conventional example of the above method is disclosed in
25408. This method of the prior art is a method of recording an information signal by irradiating a recording medium with a recording light as described in the claims. First, the intensity (peak power) of the recording light is changed. While recording a signal, the recorded signal is reproduced to determine the optimum value of the recording light intensity at which the reproduced signal is in the best state, and then, while controlling the recording light intensity to be the optimum value. This is a signal recording method for performing signal recording.
In general, the quality of an optical disk medium is maximized where the amplitude of the reproduced signal is maximized. Therefore, the best state of the reproduced signal means the maximum amplitude of the reproduced signal. Signal amplitude (PP
The optimum light intensity (optimum peak power) is determined by detecting the position where the maximum value is obtained.

Problems to be Solved by the Invention However, in the conventional method, there is a problem that the optimum peak power does not become the optimum peak power for the optical disc apparatus because the peak power at which the reproduced signal is in the best state is determined as the optimum peak power. Was.

FIG. 8A shows the peak power characteristics of a general optical disk, and FIG. 8B shows the appearance of recording marks on a recording medium obtained at each peak power. In FIG. 3A, the horizontal axis represents peak power, the vertical axis represents amplitude or S / N, and in FIG.
1, 32, and 33 indicate recording marks at each peak power, and arrows indicate the track directions. Peak power from 0 to P1
Until the power is insufficient, the recording mark is not formed sufficiently and the amplitude of the reproduced signal is insufficient. From P2, a sufficient recording mark as a reproduction signal starts to be formed. As the peak power increases from P1 to P2, the recording mark increases and the reproduced signal increases. However, after P2, the duty of the recording mark exceeds 50%, and the reproduction signal starts to decrease due to insufficient resolution. When the peak power further increases and exceeds P3, the recording medium starts to be destroyed, and the reproduction amplitude rapidly decreases. Here, the peak power at which the reproduction signal is the best (the reproduction signal amplitude is maximum or the reproduction signal quality S / N is the best in the embodiment of the related art) is given by P2. The peak power characteristics differ depending on the type of the recording medium as shown in FIGS. 34, 35 and 36, and the value of the peak power P2 at which the reproduced signal is maximum (best) is close to P1, There are a recording medium 36 near P3 and a recording medium 35 at the center and various other recording media. The two axes in FIG. 9 are the same as the two axes in FIG. 8a. On the other hand, the optimum power of the optical disk device is defined as any abnormalities (for example, servo deviation due to vibration shock, peak power deviation due to temperature change, adhesion of dust to the disk and lens, etc.) in the state of actually recording data. Since the peak power fluctuates substantially on the disk, a power range that does not hinder recording and reproduction (for example, in the peak power characteristic of FIG.
And Pc range) peak power P4 slightly higher than the center,
This is the optimum peak power for the optical disk device. The reason for selecting a slightly higher value is that the occurrence of the abnormality often causes a substantial decrease in peak power. In FIG. 9, X is called a margin power, and the margin power is an allowable value of the power reduction amount until an error occurs.

As described above, the peak power at which the best reproduction signal is obtained for the optical disk (recording medium) is (in FIG. 9,
P34, P35, P36) are not always the optimum peak power P4 for the optical disc device, and it is difficult to find the optimum peak power for the optical disc device in the conventional example that determines the peak power by finding the best state of the reproduction signal. Had become.

Further, the conventional method cannot be applied to an overwritable optical disk device. FIG. 10 is a diagram showing a light irradiation method for overwriting a phase change material.

In FIG. 10, (a) shows an optical modulation waveform, (b) shows a recording track before overwriting, (c) shows a recording track after overwriting, 40 is bias power, 41 is peak power, and 42 is peak power. The crystalline state and 43 indicate the amorphous state, respectively.
A phase change material is a material to which a signal can be overwritten by utilizing a difference in optical reflectance between an amorphous state and a crystalline state. Here, overwriting means that a new signal can be recorded on a previously recorded signal without erasing the signal. Both the amorphous and crystalline states are
As shown in Fig. 10, peak power and bias power
It is obtained by optically modulating between two laser powers. That is, regardless of the state of the recording track before overwriting, the place where the peak power is irradiated becomes an amorphous state, and the place where the bias power is irradiated can be a crystalline state. New signals can be overwritten.

Even in the above-described overwritable apparatus, it is necessary to set the optimum bias power and peak power, but in the conventional example, it is not possible to determine two powers necessary for overwriting.

An object of the present invention is to provide an apparatus that solves the above problems.

Means for Solving the Problems In order to solve the above problems, the present invention provides a start circuit for starting an optimum power setting operation, and after the instruction of the start circuit, first fixes the bias power, and further gradually reduces the peak power. Means for recording a signal while changing the signal, reproduction signal quality determination means for determining whether the recorded signal can be used, and the lowest peak power among the powers determined to be usable by the reproduction signal quality determination means. Means for determining the lower limit peak power, and
Means for recording a signal while fixing the peak power and further gradually changing the bias power; used in the reproduced signal quality judging means for judging whether the recorded signal can be used; and used in the reproduced signal quality judging means. Means for determining the lowest bias power as the lower limit bias power among the powers determined to be possible, and means for adding a predetermined power to the lower limit powers to obtain an optimum power, and Is used to overwrite the user signal.

Further, the present invention uses a bit error discriminating means as a reproduction signal quality judging means, and determines the lowest of the two powers as both lower limit powers among the powers in which bit errors can be allowed by the bit error discriminating means. The predetermined power is added to both lower powers to obtain the optimum power, and the signal of the user is overwritten.

Further, the present invention provides a method for controlling the temperature when the power is turned on, when the recording medium is replaced, when the data recorded by the user becomes defective, or after a certain period of time has elapsed after the setting of the optimum power, or when the temperature change exceeds a certain value. The operation for finding the optimum power is carried out after the occurrence of a vibration or a shock exceeding a certain value.

Effects The present invention has the above-described configuration and has an optimum peak power for an optical disc apparatus that has a margin even if the peak power fluctuates in an actual use state, regardless of the type of recording medium, even if the peak power fluctuates. It will be possible to find power. Further, according to the present invention, it is possible to set the optimum peak power between the optical disk device and the optical disk (recording medium) at the time when the user actually tries to use the optical disk device.

Embodiment FIG. 1 is a block diagram showing an embodiment of an optical disk device for finding an optimum peak power according to the present invention.

In FIG. 1, 1 is a photodetector for detecting a reproduction signal from an optical disk, 2 is an amplifier for amplifying the reproduction signal,
Reference numeral 3 denotes a demodulator for demodulating the data of the reproduction signal and an address provided on the disk, 4 denotes an unrecorded portion detector for detecting the presence or absence of the reproduction signal, 5 denotes a search circuit for searching for a target track, and 6 denotes a search circuit. A reproduction signal pass / fail judgment circuit, 7 is a modulator for modulating data from a drive control circuit described later, 8 is a recording gate generation circuit, 9 is a signal recording and / or
Or laser power control circuit for erasing, 10 is DA
The (digital / analog) converter converts the laser power value output by the drive control circuit 11 comprising a microcomputer into an analog value to determine the laser power value of the laser power control circuit. The drive control circuit 11 is also connected to the demodulator 3, the unrecorded portion detector 4, the search circuit 5, the reproduction signal quality judgment circuit 6, the modulator 7, and the recording gate generation circuit 8, and gives an instruction to each circuit. For example, in signal recording, data generated by a drive control circuit is modulated into a recording signal by a modulator 7 and recorded in a DA converter 10.
Give bias power, instruct the recording gate circuit 8,
The signal is recorded by opening the recording gate.
Reference numeral 19 denotes a start circuit for instructing to start an operation of finding an optimum peak power using these circuits. The operation of the block diagram will be described with reference to the flowchart of FIG.

In response to an instruction from the start circuit 19, the drive control circuit 11 starts work for searching for the optimum power. First, the drive control circuit 9 instructs the search circuit 5 to search for an evaluation track. The evaluation track is, for example, a track for evaluating the recording state, which is not located in the user area. The reproduction signal from the evaluation track is the photodetector 1
Through the amplifier 2 to the unrecorded portion detector 4 and the demodulator 3. By the unrecorded portion detector 4, the evaluation track
It is detected whether there is a signal already recorded or not. If there is no signal, 0 is substituted into a register N for the number of repetitions in the drive control circuit. If a signal has already been recorded, the demodulator 3 demodulates the recording signal, reads the number of times the evaluation track has been used so far (the number of repetitions) from the recording signal, and substitutes the value into the register N. . If the number of repetitions is equal to or greater than Nmax−10, the search circuit 5 searches for another evaluation track. here
Nmax is the maximum number of times that the evaluation track can be repeatedly recorded, and Nmax−10 is set so that the same evaluation track is repeatedly recorded about 10 times until the optimum peak power and the optimum bias power are determined thereafter. The number of 10 is variable.

If the newly searched another evaluation track is the last evaluation track, an error 1 is set and the user is notified, and this optimum power setting operation ends. If the other evaluation track is not the last one, the presence / absence of data on the evaluation track is checked again and the number of repetitions is read. When the number of repetitions is less than Nmax−10, the reference peak power value Pr determined by design is stored in the peak power setting register P in the drive control circuit, and the reference power determined by design is stored in the bias power setting register B. Set the bias power value Br. Next, N is set in the repetition number register N.
+1 to the evaluation track with the two powers.
Record the data. The recording signal recorded with the two powers is judged by the reproduction signal quality judgment circuit 6, and when judged as rejection (fail) as the reproduction signal, an error 2 is notified to the user and this optimum power setting work is performed. finish. When it is determined to be good (pass), first, the optimum peak power is set. The procedure for setting the optimum peak power will be described below. In the peak power setting register P, the power is set lower by dX than the currently set power, and the data is recorded by substituting data N + 1 in the repetition number register. This data is judged again by the reproduction signal quality judgment circuit 6. If the data is good, the peak power is further reduced by dX, and the peak power is maintained until the reproduction signal quality judgment circuit 6 judges that the data is not acceptable (fail). Can be lowered. When the reproduction signal quality determination circuit 6 first determines that the signal has failed (failed), the power obtained by adding dX to the value of the peak power register P at that time is the lower limit peak power at which data can be correctly recorded. The lower limit peak power is added to the margin power X
(See FIG. 9), the power Ps (Ps = P +
dX + X) is the optimum peak power for the optical disk device.

On the other hand, the optimum bias power is set in a similar procedure. The power is set lower than the currently set power by dY in the bias power setting register B, and the data is recorded by substituting data N + 1 in the repetition number register. This data is again judged by the reproduction signal quality judgment circuit 6. If the data is good, the bias power is further reduced by dY, and the bias power is kept until the reproduction signal quality judgment circuit 6 judges no (fail). Is lowered. When the reproduction signal pass / fail judgment circuit 6 first judges that the signal has failed (failed), the value of the bias power register B at that time is set to dY.
Is the lower limit bias power at which data can be recorded correctly. If the margin power Y is superimposed on the lower limit bias power, the power Bs (Bs = B + dY +
Y) is the optimum bias power for the optical disk device.

Here, the X and Y margin powers added to the both lower limit powers will be described in detail. After setting the above-mentioned optimum power, the power is set so that even if some abnormality occurs in the actual use state and a substantial fluctuation of the peak power and a fluctuation of the bias power occur, the reproduced signal does not become defective immediately. I have decided. As the margin powers X and Y, powers that are approximately equal to or more than 1/2 of the upper and lower limits of the power range in which the reproduction signal passes in the reproduction signal quality determination circuit 6 are selected (see FIG. 9). The reason for setting the value to 1/2 or more is that dust and servo deviation can be considered as main factors of the power fluctuation, and the possibility that the power is reduced is larger in each case. The margin power can be changed before the user actually records. For example, after the optimum power setting work, if the user changes the amount of margin power by detecting the time course until the data is actually recorded, or a temperature change, or a vibration shock, the margin power value can be further increased. Increases reliability.

In summary of the present invention, one of peak power and bias power is fixed, and the other is gradually (dX, d
Y), the reproduction signal pass / fail determination circuit 6 finds the minimum lower limit power at which the recording signal passes, and the power obtained by adding the margin power (X, Y) to the lower limit power is the optimum peak power. It becomes the optimum bias power.

That is, the optimum peak power and the optimum bias power of the present invention are the optimum power for the optical disk device, and the optimum power for the optical disk device is not the power at which the reproduced signal is the best, but a little abnormal (substantial recording). , Power fluctuation of erasing), the peak power and the bias power having margin power on the low power side and the high power side so as not to immediately cause a reproduction failure.

The method of setting both the peak power and the bias power has been described above.
type) Even for a disk such as a disk that records without using bias power, it is possible to set only the peak power by the method of the present invention.

The conditions for starting the operation for searching for the optimum power in the start circuit 19 are as follows: when the power of the optical disk device is turned on, or when the disk is replaced, or when a signal recorded by the user has an error of poor reproduction. Time is conceivable.

These are due to fluctuations (variations) in performance between optical disk devices and between optical disks (recording media), and are intended to calibrate the optimum power between an optical disk device and an optical disk to be used now. In addition to the above, a timer is built in the start circuit 19, after a certain time elapses, or a temperature sensor is built in, when the temperature changes more than a certain value, or a vibration shock sensor is built in, It is considered that a vibration shock of a certain value or more is applied. These are intended to calibrate the optimum power to the performance at the time of use because the environment (temperature, vibration shock, dust, etc.) has changed while using the optical disk device and the performance of the optical disk device has changed. is there. In either case, calibration of the optimum power is performed when the user does not go to write data.

FIG. 3 is a flowchart for explaining another embodiment of the present invention. The configuration of the circuit block used is the first
It is the same as the figure, but the software in the drive control circuit 11 is different. In FIG. 3, the operations from the start to the finding of the evaluation track are the same as those in the flowchart of FIG. However, the upper limit value of the number of repetitions is set to Nmax-2 because the same evaluation track is used twice before finding the optimum power, and this value is variable.

Generally, an optical disc on which data can be recorded has a sector structure, and an evaluation track is also composed of a plurality of sectors. Therefore, recording is performed with the power varied in each sector. For example, the peak power and the bias power of each sector are set as follows. Peak power P0 of sector 0
Sets the reference peak power value Pr determined by design, and at the same time, the bias power B0 sets the reference bias power value Br determined by design. Sector 1 power P1, B1
Is the power obtained by subtracting the minute powers dX and dY from Pr and Br.
For the powers P2 and B2 of the sector 2, a power obtained by subtracting twice the minute power dX and twice the dY from Pr and Br is set. Similarly, for the powers Pm and Bm of the sector m, the power is obtained by subtracting m times the minute powers dX and dY from the above Pr and Br in each sector.

All the signals of the recorded sectors are discriminated by the reproduction signal quality judgment circuit 6, and if the reproduction signal from the sector k becomes good (pass), Pr-k.dX and Br-k.dY have the lower limit peak power. , The lower limit bias power, and P = Pr−k obtained by adding the margin powers X and Y to the respective lower limit powers.
DX + X, B = Br + kdY + Y are the optimum peak power and the optimum bias power.

If the signals recorded in all the sectors while gradually varying the power are all rejected (rejected) by the reproduction signal quality determination circuit 6, the user is notified as an error 2 and the optimal power setting operation is performed. finish.

As described above, in each of the above two methods for finding the optimum power for the optical disk apparatus of the present invention, first of all, the reproduction signal pass / fail judgment circuit 6 finds the lower limit peak power and / or lower limit bias power that can be used. The optimal peak power for an optical disc device
Bias power is set.

FIG. 4 is a diagram for explaining the principle of operation when a bit error discriminating circuit is used as the reproduction signal quality judging circuit 6, and shows a bit error rate with respect to a peak power (hereinafter, a bit error rate).
(Abbreviated as BER). Horizontal axis is peak power, vertical axis B
Indicates ER. If you gradually increase the peak power from below,
BER improves (BER value decreases), acceptable BE
R, for example, when it becomes less than or equal to 10 to the power of -4, and from this point, the reproduction signal quality judgment circuit 6 determines that the reproduction signal is good (pass).
To the drive control circuit. Therefore, the peak power at this time becomes the lower limit peak power. If the quality of the reproduction signal is determined by the BER in this manner, the change in the BER relative to the peak power near the lower limit power is large, and the lower limit peak power can be easily found. Conversely, if the lower limit power is exceeded, there is no significant change in the BER, so that it is difficult to find the peak power at which the reproduced signal is the best.

In the actual use state, it is conceivable that the substantial peak power is reduced to the lower limit power due to some abnormality. Therefore, in order to enhance the reliability of the signal at the lower limit power, the BER at the lower limit power is strictly measured as follows.

FIG. 5 shows another embodiment of the reproduction signal quality judgment circuit 6 used in the present invention. The reproduction signal of the evaluation track obtained from the amplifier 2 is input to the terminal I, and the judgment result of the reproduction signal quality judgment circuit 6 is notified from the terminal J to the drive control circuit. Usually, the reproduction signal which is an analog signal is a comparison voltage Vt obtained from the comparison voltage generation circuit 12.
(Generally, a voltage of 再生 of the amplitude of the reproduced signal) is compared by a comparator circuit 13, binarized, and sent to a bit error determination circuit 14. However, in order to increase the reliability of the signal at the lower limit power, in the process of finding the lower limit power,
The comparison voltage is switched to two voltages of Vt + dVt and Vt-dVt, and the lower limit power at which a bit error does not occur even when comparing the two voltages is set as the lower limit power of the recording and / or bias power. By setting the comparison voltage to two voltages having a width as described above, it is possible to more strictly view the reproduction signal amplitude unevenness due to insufficient peak power or the bit error due to unerased residual due to insufficient bias power.
The reliability of the recording signal at the lower limit power is improved.

Another embodiment for improving the reliability of the signal at the lower limit power is shown in FIG. FIG. 6 shows another embodiment of the reproduction signal quality judgment circuit 6. The same components as those in FIG. 5 are denoted by the same reference numerals. The signal binarized by the comparator is converted to a known PLL (Phase Locked Loop) circuit 15.
The data is extracted by the data extraction circuit 16 using the reference clock and sent to the bit error discrimination circuit 14. Usually, the reference clock is selected as the data clock frequency fc. However, in order to increase the reliability of the signal at the lower limit power, in the process of finding the lower limit power, the frequency of the reference clock is set to fc +
By switching to two frequencies of dfc and fc-dfc, the lower limit power at which no bit error occurs even when data is extracted at the two frequencies is set as the lower limit power of the recording and / or bias power. As described above, by setting the frequency of the reference clock to two frequencies having a width, S / N deterioration due to insufficient peak power or bias power, in other words, jitter of the reproduction signal (in the time axis of the reproduction signal, Bit errors due to fluctuations can be seen more severely,
The reliability of the recording signal at the lower limit power is improved.

FIG. 7 is a diagram for explaining an operation principle when a reproduced signal amplitude discriminating circuit is used as the reproduced signal quality judging circuit 6, and shows a reproduced signal characteristic with respect to a peak power. The horizontal axis indicates the peak power, and the vertical axis indicates the reproduced signal amplitude. When the peak power is gradually increased from the low power side, the amplitude of the reproduction signal increases, and when the amplitude exceeds the allowable amplitude Vb, the reproduction signal quality determination circuit 6 determines that the reproduction signal is good (pass). ) To the drive control circuit.
Therefore, the peak power at this time becomes the lower limit peak power. As described above, the change in the reproduction signal amplitude with respect to the peak power near the lower limit power is large, and the lower limit peak power can be easily found. Conversely, if the power exceeds the lower limit power, there is no large change in the reproduction signal amplitude, so that it is difficult to find the peak power at which the reproduction signal amplitude becomes maximum as in the conventional example.

Effect of the Invention As described above, the present invention finds the peak power and the lower limit power of the bias power, and then finds the optimum power for the optical disk device. Therefore, the optimum power can be easily found, and It is possible to reliably set the optimum power uniquely. Further, the optimum power found in the present invention is the optimum power for the optical disk device, and therefore, even if an error such as a servo shift due to an environmental change or a power fluctuation occurs in an actual use state,
There is margin power until the reproduction signal becomes defective, and the stability of the optical disk device is improved.

Furthermore, according to the present invention, the quality of the signal at the lower limit power is high because the recording / reproducing signal at the lower limit power is judged more strictly than usual and the quality of the signal is determined. Furthermore, according to the present invention, even if there is a variation (variation) in performance between optical disc devices and between optical discs (recording media),
Optimal power between the optical disk device to be used now and the optical disk can be calibrated, and the performance of the optical disk device changes due to changes in the environment (temperature, vibration shock, dust, etc.) while using the optical disk device However, since the optimum power can be calibrated to the performance at the time of use, the performance varies,
This has the effect of providing a highly reliable optical disk device that is not affected by environmental changes.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disk apparatus capable of setting an optimum power according to an embodiment of the present invention, FIG. 2 is a flowchart showing an embodiment of an optimum power setting method of the present invention, and FIG. FIG. 4 is a flowchart showing another embodiment of the power setting method. FIG. 4 is a graph for explaining the principle of one embodiment of the reproduction signal quality judgment circuit used in the present invention.
FIG. 5 is a block diagram of one embodiment of a reproduction signal quality judgment circuit used in the present invention, FIG. 6 is a block diagram of another embodiment of a reproduction signal quality judgment circuit used in the present invention, and FIG. 8 and 9 are graphs of peak power characteristics for explaining the problems of the conventional example, and FIG. 10 is a phase change type circuit for explaining the principle of another embodiment of the reproduction signal quality judgment circuit used. FIG. 3 is an explanatory diagram of the principle of recording on an optical disc. 6 ... reproduction signal quality judgment circuit, 9 ... laser power setting circuit, 11 ... drive control circuit, 12 ... reference voltage generation circuit, 13 ... comparator circuit, 14 ... bit error judgment circuit, 15 ... PLL Circuit, 16 Data discriminating circuit, 19 Start circuit, 40 Bias power, 41
... peak power.

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification code FI G11B 20/18 572 G11B 20/18 572F (72) Inventor Kenzo Ishibashi 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-61834 (JP, A) JP-A-63-121130 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 7/00 G11B 7 / 125 G11B 20/18

Claims (6)

(57) [Claims] 1. An apparatus for recording a signal by irradiating a recording medium with a binary laser beam having a bias power and a peak power, wherein the bias power is first fixed, and the peak power is gradually changed. Means for recording the signal while
Means for determining whether the recorded signal can be used or not, and means for determining the lowest peak power as the lower limit peak power among the powers determined to be usable by the reproduced signal quality determination means. Means for recording a signal while fixing the peak power and further gradually changing the bias power; the reproduction signal quality determination means for determining whether the recorded signal can be used; and Among the powers determined to be usable by the signal quality determination means, means for determining the lowest bias power as the lower limit bypass power,
An optical disk device capable of setting an optimum power, comprising means for adding a predetermined power to obtain an optimum power. 2. The optical disk apparatus according to claim 1, further comprising a bit error determining means as a reproducing signal quality determining means. 3. A comparison signal generating means having a standard voltage, a voltage higher than the reference voltage, and / or a comparison voltage lower than the standard voltage as reproduction signal quality judgment means, 3. The apparatus according to claim 1, further comprising: comparator means for comparing the binary signals to obtain a binary signal; and bit error discriminating means for the binary signal.
Optical disc device capable of setting the optimum power described in the item. 4. A means for judging the quality of a reproduced signal, a comparator means for binarizing the reproduced signal, a standard frequency,
A phase lock (PLL) having a higher frequency than the standard frequency and / or a lower frequency than the standard frequency
2. The method according to claim 1, further comprising: means for extracting data of the binary signal based on a frequency higher and / or lower than the standard; and a bit error discriminating means for the data. 3. An optical disk device according to claim 2, wherein the optimum power can be set. 5. A reproduction signal amplitude judging means as reproduction signal quality judging means, wherein said reproduction signal amplitude judging means determines a lower limit power at which the reproduction signal amplitude is allowable as a lower limit power, and said lower limit power is determined. 2. The optical disk apparatus according to claim 1, further comprising: means for adding an obtained power to an optimum power. 6. A method of recording and / or erasing a signal by irradiating a recording medium with a laser beam, when power is turned on, when a recording medium is replaced, or when data recorded by a user becomes defective. Time, or after a certain period of time has elapsed after the optimal power calibration, or after a temperature change of a certain value or more, or after a vibration or a shock of a certain value or more is applied. 6. The optical disk apparatus according to claim 1, wherein the power is set.