JP2003059048A - Control method, measuring method and controller for laser power - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for laser power which can precisely obtain the best value of power of a light beam irradiating an optical recording medium capable of recording in a short time when information is recorded on the optical recording medium. SOLUTION: By the control method for the laser power which sets the optimum recording laser power value by irradiating the optical recording medium with divided recording laser light by test with a plurality of different recording power values and erasure power values on a time-division basis at specific time intervals, the recording power values and erasure power values are set so that the erasure power values increase and decrease contrary to the recording power values at the specific time intervals; and the recorded signal is reproduced and a value at each specific time of the amplitude center of the reproduced signal corresponding to a signal of the lowest frequency component pulses and a value at each specific time of the amplitude center of the reproduced corresponding to the signal of the highest frequency component pulses are compared with each other to determine the optimum recording laser power value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repeatable recordable digital versatile disc (hereinafter referred to as "DVD-R").
W)) or the like, which is a phase-change medium, and a laser power control method for controlling the recording power and the erasing power of a light beam irradiated at the time of recording information.
The present invention relates to a laser power measuring method and a laser power control device.

[0002]

2. Description of the Related Art Currently, CD-RW, DVD-R and DVD
An apparatus for recording / reproducing on / from a phase change medium such as + RW is known. In such an apparatus, the quality of recording depends on the physical characteristics and optical characteristics of the phase change medium, the pickup used for recording, the laser wavelength, etc., and therefore it is necessary to control to an optimum recording laser power value. .

A conventional calibration method using an organic dye medium is disclosed in, for example, Japanese Patent No. 3159454.
Explained. Here, as shown in FIG. 9A, the dedicated track 2 provided on the R-CD 1 is set to
The recording signal c shown in (d) is converted to the ATIP (Abso
lute Time In Pregroove) Based on the sync (synchronization signal) a, as shown in FIG.
Say. Recording is performed while changing the recording signal c for each.

A specific example of the recording signal c is shown in FIG. As can be seen from FIG. 1, the recording signal c1 does not use the EFM recording signal c, but uses only 11T and 3T. The 11T pulse section is 3 times, the 3T pulse section is 10 times, and the 11 pulse section is 3 times again. A total of 132T for 12 3T pulse sections
It is formed in a repeating pattern. As a result, “H” section of 11T pulse → 11T × 3 = 33T “L” section of 11T pulse → 11T × 3 = 33T “H” section of 3T pulse → 3T × 11 = 33T “L” section of 3T pulse → As in 3T × 11 = 33T, the number of “H” level and “L” level in each pulse section is the same, in other words, the duty ratio is 50%.
It means that T is the channel frequency.

After that, the track 2 on the R-CD 1 is read and reproduced, and the signal obtained by removing the DC component of the obtained EFM RF signal (by the AC coupling capacitor) is the AC coupling reproduction signal g of FIG. 9 (e). The value of the recording laser power b (B4) when the relationship of the center position of the amplitude of the 3T signal with respect to the center of the 11T signal amplitude of the AC coupled reproduction signal g (hereinafter, this relationship is referred to as asymmetry) is matched.
The optimum recording laser power value was used for calibration. FIG. 10 shows the eye patterns of the portions A, B, and C in FIG. 9 (e). As can be seen from FIG. 10, the B4 part can be said to be the optimum power value.

[0006]

However, in a medium using such an organic dye as a recording layer, the relationship (deviation amount) of the center position of the amplitude of the 3T signal with respect to the center of the amplitude of the 11T signal (hereinafter, this relationship will be described). Of the asymmetry) is large with respect to the recording power, but there is a problem that the phase change medium has a small change rate and is difficult to detect.

Further, in a medium using a phase change medium as a recording layer, the asymmetry also changes when the erasing power is changed with respect to the recording power. Therefore, conventionally, the ratio of the recording power and the erasing power (recording power) is changed. And the erasing power ratio ε = erasing power / recording power) are fixed and measured (FIG. 7A), or the erasing power value is fixed with respect to the recording power (FIG. 7B). there were. However, in a high-density recording medium such as DVD-RW,
In these two methods, as shown in FIG. 3, in the method in which the ratio of the erasing power is fixed and measured, the change rate of the asymmetry with respect to the recording power is about 1% / mW,
Especially, there is a problem that the inclination becomes smaller in a high power region. Further, even in the method of fixing the value of the erasing power with respect to the recording power, although the change rate of the asymmetry with respect to the recording power is improved to about 2% / mW, the detection accuracy of the detection circuit of the device and the control of the optimum recording power are controlled. Improvement was necessary from the range.

Further, if the method of fixing the value of the erasing power to this recording power is also used, there are the following problems.

Generally, in an apparatus, when the optimum value of the recording laser power is to be obtained, the optimum values of the recording power and the erasing power may be separately obtained when a new disc is inserted. Once the optimum power is obtained, most of the fluctuations in power due to temperature changes, changes over time, and dust adhering to the optical system are absorbed.
At this time, the relationship between recording power and erasing power (ratio ε) is constant. Also, since this value (ratio ε) is stated in the standard specifications of the desired disc, the device reproduces this value (ratio ε) from the disc and sets the optimum power with this ratio fixed. do it.

However, in the method of fixing the value of the erasing power with respect to the recording power, since the value of the erasing power is fixed, recording is performed while changing the relationship (ratio ε) between the recording power and the erasing power. Since the asymmetry changes due to the fluctuation of the erasing power, even if the target asymmetry value is obtained at the recording power of a certain measurement point, the relationship between the recording power and the erasing power at that time is ε. If this is not the case, the only way is to change the erasing power so that it approaches the target again and then perform similar measurements to bring it closer to the target, which requires a long adjustment time and recording area, and cannot be realized in the device. Met.

Therefore, it is an object of the present invention to provide a laser power control method, a laser power measurement method, and a laser power control device for accurately obtaining an optimum recording laser power value in a short time.

[0012]

In order to solve the above problems, the present invention provides a laser power control method having the following configuration,
Provided are a laser power measuring method and a laser power control device. (1) The optimum recording laser power value is set by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating a plurality of different recording power values and erasing power values, respectively. In the method for controlling the laser power, the step of setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value, The recorded signal is reproduced, and the value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time and the predetermined value of the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse. And a step of determining an optimum recording laser power value by comparing values for each time, a laser power control method. (2) The optimum recording laser power value is measured by irradiating a recordable optical recording medium with a recording laser on a test basis every predetermined time and irradiating it with a plurality of different recording power values and erasing power values. In the method for measuring the laser power, the step of setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value,
The recorded signal is reproduced, and the value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time and the predetermined value of the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse. And a step of determining a relationship of values for each time as an asymmetry value and measuring the asymmetry value as a slope with respect to the recording power value. (3) The optimum recording laser power value is set by irradiating a recordable optical recording medium with a recording laser on a test basis every predetermined time and irradiating with a plurality of different recording power values and erasing power values. In the method for controlling the laser power, the step of setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value,
The recorded signal is reproduced, and the value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time and the predetermined value of the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse. A step of determining a value for each time as an asymmetry value, a relationship between the recording power and the erasing power, a change in the asymmetry value with respect to a change in the erasing power, and a ratio of a target recording power and a target erasing power. And a step of determining an optimum recording laser power value from a target asymmetry value in the relationship, the laser power control method. (4) The optimum recording laser power value is set by irradiating a recordable optical recording medium with a recording laser on a test basis every predetermined time and irradiating with a plurality of different recording power values and erasing power values. In the laser power control device, means for setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value, The recorded signal is reproduced, and the value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time and the predetermined value of the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse. Means for determining an optimum recording laser power value by comparing values for each time, and a laser power control device. (5) The optimum recording laser power value is set by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating a plurality of different recording power values and erasing power values. In the laser power control device, means for setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value, The recorded signal is reproduced, and the value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time and the predetermined value of the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse. A means for determining a value for each time as an asymmetry value, a relationship between the recording power and the erasing power, and a change in the asymmetry value with respect to a change in the erasing power. And a means for determining an optimum recording laser power value from a target asymmetry value in the relationship between the ratio of the target recording power and the target erasing power, and a laser power control device. (6) The optimum recording laser power value is set by irradiating a recordable optical recording medium with a recording laser on a test basis every predetermined time and irradiating with a plurality of different recording power values and erasing power values. In the method for controlling the laser power, a group in which the recording power value and the erasing power value are changed at each of the predetermined time intervals centering on a target value of the ratio of the erasing power to the recording power value is A step of setting the reproduction power as a plurality of patterns, reproducing the recorded signal, and a value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time, and the highest frequency component pulse Determining the optimum recording laser power value by comparing the values of the amplitude center of the reproduction signal corresponding to the signal at each of the predetermined time intervals. Method of controlling the laser power to be. (7) The optimum recording laser power value is set by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values. In the controller for controlling the laser power, a group in which the recording power value and the erasing power value are changed at each of the predetermined time intervals centering on a target value of the ratio of the erasing power to the recording power value is Means for setting the reproduction power as a plurality of patterns, the recorded signal is reproduced, and the value of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse at each predetermined time and the highest frequency component pulse Means for determining the optimum recording laser power value by comparing the values of the amplitude center of the reproduced signal corresponding to the signal at each of the predetermined times. The control device of the laser power to be.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 2 shows a main part of a recordable / reproducible DVD-RW recorder for implementing the power control method of the present invention. During test recording, the DVD-RW 1 is rotated by the spindle motor 7, and the rotation is controlled by the servo circuit 10. At this time, the pickup 6 is controlled by the servo circuit 10 at a position corresponding to the track 2. Calibration recording signal generation circuit 17
The (test recording signal) is controlled by the control signal 1 from the controller 16 to generate the recording signal c1, which is input to the recording amplifier 4 via the changeover switch 18 controlled by the changeover signal r.

The recording signal c1 is stored in the ROM or the like in the controller 16 in advance without depending on the calibration recording signal generating circuit 17 and the pattern data of the recording signal c1 is read out as appropriate to the recording amplifier 4 May be given to.

The laser diode of the pickup 6 is driven, and the recording and erasing laser power b at this time is given through a controller (servo / mechanical control microcomputer) 16 and a D / A converter 14, which will be described later. This is performed by variably controlling the recording amplifier 4 as shown in FIG. 4C by the recording laser power control signal mp and the erasing laser power control signal me.

At the time of reproducing the test recorded signal,
The recording / reproducing switch 8 is switched to the PB side, and the pickup 6
The read signal of R is amplified by the reproduction amplifier 9 and then R
The F signal is output to the decoder. On the other hand, the RF signal output from the reproduction amplifier 9 is a timing signal of a reproduction signal from a decoder which does not detail any one of the peak detection circuit 12, the bottom detection circuit 13, and the average value detection circuit 19 including the sample hold circuit. The switching signal 20 is used to sample and hold the signal, and the switching circuit 21 switches the sampled and held signal. The switched signal is input to the controller 16 via the A / D converter 15 based on the timing signal of the reproduction signal from the decoder, and is used for calculating the optimum power value described later.

The recording signal c1 shown in FIG. 1 is similarly used as the recording signal for test recording. A view corresponding to FIG. 9 is shown in FIG. The recording position is the test recording area (PCA) on the inner circumference of the DVD-RW. FIG. 4B is a method shown in FIG. 4C according to the LPP (land pre-pit) timing signal according to the DVD-RW standard, and the power is changed so that the erasing power is decreased as the recording power is increased. And record. When changing in steps, the relationship between the recording power and the erasing power is set so that the target value of the recording power and the erasing power, ε, comes to the step near the center of the step (the amount of this change is the disc or pickup). Determined by characteristics). This concrete numerical value is shown in FIG.7 (c).

Here, ε is set to the target value of 0.5 in the fourth step while changing the power from 1 step to 7 steps. The recording power and erasing power values of 12 mW and 6 mW at this time are also set to the target values. In the algorithm for asymmetry detection described below, the erasing power may not be decreased, but the erasing power in FIG. 6B may be set to a constant value for recording.

By performing the recording while changing the power so that the erasing power is decreased as the recording power is increased, the inclination of asymmetry becomes larger as compared with FIG. 3 as shown in FIG. 5% / mW),
Since the amount of change in asymmetry with respect to the change in power becomes large, detection can be performed more accurately.

As can be seen from the recording signal c1 (FIG. 1),
Instead of using the 8/16 modulated recording signal c of DVD,
Only 11T and 3T are used, 3 times for 11T pulse section, 3
T pulse section 10 times, 11 pulse section 3 times 3
The T pulse section is formed by a repeating pattern of 12 times, for a total of 132T cycles. As a result, “H” section of 11T pulse → 11T × 3 = 33T “L” section of 11T pulse → 11T × 3 = 33T “H” section of 3T pulse → 3T × 11 = 33T “L” section of 3T pulse → As in 3T × 11 = 33T, the number of “H” level and “L” level in each pulse section is the same, in other words, the duty ratio is 50%.
It means that

A control algorithm for reproducing the recording signal and calculating the optimum recording power will be described. This control algorithm is similarly used when the erasing power is reduced and when the erasing power is recorded at a constant value.

First, move to the place where the test recording was made,
The LPP timing signal obtained from the decoder of the target address is detected, the peak value of the 11T signal sampled and held with the timing signal corresponding to each recording position and the bottom value of the 11T signal are measured, and the peak value of the 11T signal is calculated. And the center value of the bottom value is calculated. Next, the average value detection output which is the center of the 3T signal is measured, and the average value detection output is compared with the center value of the peak value and the bottom value. Asymmetry is obtained by dividing the difference between the average value of the peak value and the bottom value and the average value detection output by the peak-to-peak value of the peak value and the bottom value.

This asymmetry is 0% or a value close to 0% (between -5% and + 15% in DVD-RW), which is the closest to the recording power value and the erasing value which are related to the values written on the disc. The power value is compared as the erase power value / recording power value.

This value ε is the time when the optimum value of the recording power is obtained at the time of inserting the disc, or the ε value of a predetermined value such as the value written on the disc or the power corresponding to the ε value or It is determined whether the step position is reached. Then, if the ε value in the predetermined range is reached, the recording power value and the erasing power value at that time are determined as the optimum powers, and if the measured ε value is lower than the target ε value, the emission is actually performed. Since the power being set is small, the power to be set stepwise is increased on the basis of the difference between the recording power value and the erasing power value as shown in FIG. The recording power value and the erasing power value can be obtained by obtaining the target ε value by the asymmetry value.

On the contrary, when the measured ε value is larger than the target ε value, it means that the actually emitted power is large. Therefore, the power set stepwise is set as the recording power value and the erasing power. It is possible to set the recording power value and the erasing power value to obtain the target ε value with the target asymmetry value by making each value smaller and performing again.

As described above, if the optimum power is not obtained in one test recording, it takes time if it is repeated many times. Therefore, as a second embodiment for shortening this time, the test recording and its The measuring method will be described.

(Second Embodiment) Test recording is performed in the same manner as in the first embodiment, but the recording power and the erasing power are set as shown in the pattern of FIG. 7 (e). So here, 1
Among the patterns from 9 to 9, three blocks are set as one block, and 0.68 and 0.37 are set around the target ε value of 0.5, and the recording power to obtain these ε values is set. And the erasing power are set in three steps at substantially equal intervals. Asymmetry values recorded and reproduced with this recording pattern are shown in FIG. Recording steps 1 to 9 correspond to measurement results 1 to 9. Of the three groups 1 to 3, 4 to 6, and 7 to 9, the target ε value of 0.
Which of steps 2, 5, and 8 which is the step at the time of 5 is closer to the optimum value is determined.

As a method therefor, for example, assuming that the center of each group is at the position of 0.5 of the target ε value (the center of 1 and 3 becomes 2), the center of 1 and 3 and 2 The average value of 4 and 6 and the average value of 5 and the average value of 7 and 9 and 8 are calculated, respectively, and the values of 2, 5 and 8 which are the closest to the target asymmetry value among the three comparisons are calculated. Decide which one of them is the optimum power. In addition to this, the slope is calculated from three data (for example, 1, 2, 3), the power of the value that becomes the target asymmetry is calculated, and the value when the calculated power is closest to the target ε is calculated. The optimum power may be determined.

If it is not close to the optimum value, this pattern may be changed and test recording and measurement may be performed again.
You may correct by calculation. By using this method, it is possible to improve accuracy as compared with the case where the optimum power is determined from only the results of 2, 5, and 8 obtained when the measurement result is set to 0.5, for example.

(Third Embodiment) As a third embodiment of the present invention, a method for obtaining the optimum power by calculation will be described. FIG. 6 shows the actual asymmetry characteristics obtained in FIGS. 3 and 5 and the results obtained from many physical characteristics as a conceptual diagram of the asymmetry characteristics. Actually, the ε value of the erase power / recording power is set to ε1, ε2, ε3 (ε1 <ε2 <ε3
Then, for example, ε1: 0.5, ε2: 0.55, ε3: 0.
In the case of 6), these three lines are at substantially equal intervals, and each line has a characteristic that can be approximated to a straight line near the optimum power. The other line G is the result of measurement when the erase power is fixed or the erase power is decreased as the recording power is increased. Similarly, a characteristic that can be approximated to a straight line is obtained near the optimum power.

Therefore, the following is assumed for generalization. The asymmetry slope a is fixed when ε is fixed.
K is the contribution factor of the erasing power to the asymmetry change
1 and K2 are constant. Assuming that the erasing power contribution coefficient is K1ε, Asym () = a * P () − K1 * ε () + K2 (1) Equation Asym () Asymmetry during measurement a Asymmetry slope P () Recording power during measurement The ratio of the erasing power to the recording power at the time of measuring ε () can be used.

Line G in the figure is the measurement result when the erasing power is fixed (or changed in the opposite direction), and ε when ε is fixed.
The characteristics of 1, ε2 and ε3 overlap at points B, C and D, respectively. At the overlapping points B, C and D, the following formula is established. Asym (ε1) = a * P (B) -K1 * ε1 + K2 ... (2) Formula Asym (ε2) = a * P (C) -K1 * ε2 + K2 ... (3) Formula Asym (ε3) = a * P (D) -K1 * ε3 + K2 (4) At least from the simultaneous equations of these three equations, a, K1,
K2 is obtained. As a result, the target asymmetry power P () becomes P () = (Asym () + K1 * ε ()-K2) / a (5) formula, and the recording is performed by the method of the above-described embodiment once. By performing the measurement, the recording power corresponding to the target asymmetry value and the target ε value can be obtained. The erasing power is obtained by multiplying the recording power by the ε value.

Since this method is a conceptual method, it is more preferable to re-record with the optimum recording and erasing power obtained by this method and confirm the asymmetry, jitter, and error rate.

Further, the equation (1) includes the constant K2 on the assumption that the asymmetry does not become 0 when the recording power and the erasing power are very close to 0. = A * P ()-K1 * [epsilon] () ... (6) may be satisfied depending on the physical characteristics, so this may be used. In this case, since the unknown number to be obtained is 2, the solution can be obtained by two simultaneous equations with at least two measurement values.

In addition to this, it is also possible to formulate an approximate expression that approximates the actual measurement result. That is, according to the present invention in this embodiment, if the power is varied while keeping the recording power and the erasing power in the optimum ratio relationship, the problem that the amount of asymmetry change is small and the detection cannot be performed accurately is referred to as the recording power. The relationship between the erasing power is changed and recording is performed, and the results are taken into account to obtain the value close to the optimum power from the measurement results of asymmetry with large changes, taking into consideration the effect that the erasing power has on the asymmetry change. is there.

More practically, when it is expected that there are many measurement errors due to the relationship between the disc and the pickup,
Improving the accuracy of the above formula by averaging a plurality of measurement data by performing a plurality of calculations, or changing the weighting of the data near the optimum power or near the asymmetry value of 0. Can be done.

In the present embodiment, the recording signal c1 shown in FIG. 1 was used as the recording signal for the test recording, but not only this signal but also signals of different combinations of T may be used.
Alternatively, a random signal including all signals may be used for recording, and at the time of reproduction, the difference between the peak and bottom centers of the signal and the center position of the high frequency component may be measured as an asymmetry value.

Further, in the method shown in FIG.
As shown in (c) and (d), recording is performed by simply changing the power so that the erase power decreases as the recording power increases. Is set so that the target recording power / erase power ratio value ε comes to a step near the center of the step (the fourth step in FIGS. 7C and 7D) (variable between these steps). The amount is determined by the characteristics of the disc and pickup).

Further, in the embodiment shown in FIGS. 7 (c) and 7 (d),
The recording pattern for test recording at one time is recorded with one power corresponding to one ε value, but is recorded with a plurality of power values for almost the same ε value. For example, FIGS. 7 (c) and 7 (d)
When recording and reproducing in combination, the best power may be determined as a matrix. Note that this ε
In the method of setting the optimum value position, the erasing power may be set to a constant value for recording as shown in the pattern of FIG.

The asymmetry described in the text is the center position relationship of the high frequency signal component with respect to the center of the amplitude of the low frequency signal in the reproduced signal.
And β in the β method described in the DVD-RW standard, or the name of symmetry.

[0042]

As described above, according to the present invention, when the best value of the recording and erasing power is detected, the erasing power is increased and decreased in the opposite direction to the inclination of the asymmetry value with respect to the power. Is increased, the detection accuracy of the optimum recording power is improved, and the optimum power is determined in consideration of the influence of the erase power on the asymmetry change, and the optimum power is obtained in a short time. As a result, it is possible to maintain compatibility between devices and manufacturers at the time of recording / reproducing and contribute to the development of the market.

[Brief description of drawings]

FIG. 1 is a waveform diagram of a recording signal.

FIG. 2 is a block diagram of a main part of a DVD-RW recorder that is an embodiment of the present invention.

FIG. 3 is an explanatory diagram of conventional asymmetry characteristics.

FIG. 4 is a time chart showing an embodiment of the method of the present invention.

FIG. 5 is an explanatory diagram of asymmetry characteristics obtained by the present invention.

FIG. 6 is a conceptual diagram of asymmetry characteristics obtained by the present invention.

FIG. 7 is an explanatory diagram showing recording patterns of recording power and erasing power of a conventional example and an example of the present invention.

FIG. 8 is an explanatory diagram of asymmetry characteristics obtained by the present invention.

FIG. 9 is a time chart showing an example of a conventional recording laser power calibration method.

FIG. 10 is an explanatory diagram of an eye pattern of a DC coupled reproduction signal in the case of FIG.

[Explanation of symbols]

1 ... R-CD 2 ... Truck 3 ... Calibration area 4 ... Recording amplifier 6 ... Pickup 7 ... Spindle motor 8 ... Recording / reproduction switch 9 ... Playback amplifier 10 ... Servo circuit 11 ... AC coupling capacitor 12 ... Peak detection circuit 13 ... Bottom detection circuit 14 ... D / A converter 15 ... A / D converter 16 ... Controller 17 ... Recording signal generating circuit for calibration 18 ... Changeover switch 19 ... Changeover switch 20 ... Comparator 22 ... switch a ... ATIP sink b ... Recording laser power c ... Recording signal c1 ... Recording signal d ... AC coupled reproduction signal e ... DC coupled reproduction signal f ... DC coupled reproduction signal g ... DC coupled reproduction signal h ... DC coupled reproduction signal i ... Recording signal switching pulse j ... 11T section signal k ... Playback signal l ... Control signal attenuation value m ... Recording laser power control signal n ... Recording / reproduction switching signal o ... Recording signal switching control signal p ... Comparison output with 11T amplitude center voltage q ... integral output PREC ... Recording power r ... switching signal

Continued front page    (72) Inventor Kaoru Kosaka             3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa             Local Victor Company of Japan, Ltd. F-term (reference) 5D090 AA01 BB05 CC01 CC18 DD03                       EE01 EE05 FF36 HH01 JJ12                       KK03                 5D119 AA23 AA26 BA01 BB04 DA02                       HA19 HA45 HA52

Claims (7)

[Claims] 1. An optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser on a test basis every predetermined time and irradiating with a plurality of different recording power values and erasing power values. In the method for controlling the laser power, the step of setting the recording power value and the erasing power value in the direction in which the erasing power value increases and decreases in the opposite direction with respect to the recording power value at each of the predetermined time degrees. And reproducing the recorded signal, the value for each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse And a step of determining an optimum recording laser power value by comparing values for each predetermined time, the laser power control method. 2. The optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values, respectively. In the method for measuring the laser power for measuring, the step of setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value. And reproducing the recorded signal, the value for each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse Determining the relationship of values at each predetermined time as an asymmetry value and measuring the asymmetry value as a slope with respect to the recording power value. Method of measuring the laser power to be. 3. The optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser as a test at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values, respectively. In the method for controlling the laser power, the step of setting the recording power value and the erasing power value in the direction in which the erasing power value increases and decreases in the opposite direction with respect to the recording power value at each of the predetermined time degrees. And reproducing the recorded signal, the value for each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse Determining a value for each predetermined time as an asymmetry value, a relationship between the recording power and the erasing power, and the asymmetry with respect to a variation in the erasing power. And a step of determining an optimum recording laser power value from a target asymmetry value in a relationship between a target recording power and a target erasing power ratio, the laser power control method. 4. An optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values, respectively. A laser power control device for setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value. And reproducing the recorded signal, the value for each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse Means for determining an optimum recording laser power value by comparing values for each predetermined time, and a laser power control device. 5. An optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values, respectively. A laser power control device for setting the recording power value and the erasing power value at each of the predetermined times in a direction in which the erasing power value increases or decreases in a direction opposite to the recording power value. And reproducing the recorded signal, the value for each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the amplitude center of the reproduction signal corresponding to the signal of the highest frequency component pulse A means for determining a value for each predetermined time as an asymmetry value, a relationship between the recording power and the erasing power, and the asymmetry with respect to variations in the erasing power. And a means for determining the optimum recording laser power value from the target asymmetry value in the relationship between the change in the value and the ratio between the target recording power and the target erasing power, and a laser power control device. 6. An optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values, respectively. In the method of controlling the laser power for setting the recording power value and the erasing power value at each of the predetermined time intervals, a group in which the target value of the ratio of the erasing power to the recording power value is changed is recorded, A step of setting a plurality of patterns in which power and reproduction power are changed, reproducing the recorded signal, and a value for each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the highest frequency Determining the optimum recording laser power value by comparing the values of the amplitude center of the reproduction signal corresponding to the signal of the component pulse at each of the predetermined times. The method of the laser power, wherein the door. 7. The optimum recording laser power value is obtained by irradiating a recordable optical recording medium with a recording laser on a test basis at predetermined time intervals and irradiating with a plurality of different recording power values and erasing power values, respectively. In the laser power control device for setting, the recording power value and the erasing power value are recorded at each of the predetermined time intervals by changing a group centered on a target value of the ratio of the erasing power to the recording power value, A means for setting the power and the reproduction power as a plurality of patterns, and reproducing the recorded signal, and the value at each predetermined time of the amplitude center of the reproduction signal corresponding to the signal of the lowest frequency component pulse, and the highest frequency. Means for determining the optimum recording laser power value by comparing the values of the amplitude center of the reproduction signal corresponding to the signal of the component pulse at each of the predetermined times. Controller of the laser power, wherein the door.