JPH06195716A - Optical disk apparatus and setting method for its recording power - Google Patents

Abstract

PURPOSE:To easily set an optimum recording power by a method wherein the amplitudes of reproduced signals and the amplitudes of reproduced signals corresponding to 1nT erasing level signals are measured for a plurality of different recording powers. CONSTITUTION:Information recorded on an optical disk 9 is picked up again by an optical head 10 and converted into electrical signals. After the electrical signals are amplified by a reproducing amplifier 3, the signals are converted into digital data by an AD converter 4 and stored in a memory 5. A CPU 6 process the data stored in the memory 5 to set an optimum power. In this case, a relation between a recording power and a value Va/Vb (wherein Va denotes the amplitude of a reproduced signal and Vb denotes the amplitude of a reproduced signal corresponding to an 1nT erasing level signal) is approximately linear. If it is confirmed that the relation between the value Va/Vb and the recording power can be expressed as a linear relation, for that disk, the optimum power can be set highly accurately by measuring the values Va/Vb corresponding to at least 2 points of the recording power values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device which uses an optical disk as an information storage carrier and records and reproduces information by using light, and more specifically, sets a recording power when recording on the carrier. The present invention relates to an optical disk device equipped with a device and a recording power setting method thereof.

[0002]

2. Description of the Related Art As a method of recording information on an optical disc, the state of a recording medium is locally changed by modulating the intensity of a laser beam applied to the disc to create two different states and retain the record. The method of doing is widely used. These two states are represented by binary data “1”,
Recording corresponding to "0" is called recording of binary digital data.

In such a method of modulating the intensity of the laser beam, the size of the mark to be recorded depends on the intensity (power) at the time of recording, so that the optimum recording power naturally exists. Further, since recording is performed by raising the temperature of the medium due to laser light irradiation, the optimum recording power varies depending on the material of the recording medium, the structure of the disc, and the temperature at the time of recording. Therefore, the optical disk device is equipped with a recording power setting device for setting the optimum recording power of the laser beam at the time of recording.

Conventionally, as a method for obtaining an optimum recording power, for example, as described in JP-A-3-91124, recording is performed with different laser powers,
A method is used in which the error rate of reproduced data at each recording power is measured and used as the center value of the recording power range in which the error rate is below a predetermined value.

[0005]

According to this method, the power range in which the error rate is equal to or less than a constant value can be obtained relatively easily. However, near the center of the range, the change in the error rate with respect to the change in recording power is small. However, there is a problem that it is difficult to accurately obtain the recording power with the least error.

Furthermore, a method (PULSEWIDTH MODURATION, which uses the edge position of the recording mark as an information position,
When using the PWM recording method), the deviation of the recorded mark length from the reference value directly leads to an error. Therefore, the center position of the mark is used as the information position (PULSE POSITION MODULATION, hereinafter PPM recording). It is necessary to set the recording power more accurately than that of the method).

[0007]

According to the recording power setting method of the present invention, the intensity of a laser beam at the time of recording is modulated to record binary digital data on a medium. A method of setting power, wherein n is a positive integer with respect to a clock period T of the recording signal as the binary recording signal, and 2n is used before and after each.
A recording level signal of 1 nT surrounded by an erasing level of T or more, and a recording level signal of 1 nT each surrounded by a recording level of 2 nT or more.
The NRZ data composed of repetitions of the nT erase level signal is recorded, and the reproduction signal amplitude Va corresponding to the 1nT recording level signal and the reproduction signal amplitude Vb corresponding to the 1nT erase level signal are recorded at a plurality of different recording powers. It is characterized in that the optimum recording power is obtained based on the magnitude relationship between Va and Vb at each measured recording power.

It is preferable that the recording laser pulse corresponding to the recording level signal of 2 nT or more is set as a set of a plurality of divided pulses partially or entirely.

The length of the erasing or recording level surrounding 1nT can be made different before and after the level signal of 1nT.

The optical disk device of the present invention comprises a recording power setting device for optimizing the intensity of laser light, and records binary digital data on a medium by modulating the intensity of laser light at the time of recording. An optical disc device,
The recording power setting device includes (a) a recording level signal of 1 nT surrounded by erasing levels of 2 nT or more in the front and rear, and 2 nT or more in the front and rear with respect to a clock period T of a recording signal of laser power, where n is a positive integer. A recording data generating circuit for generating a repetition signal of an erase level signal of 1 nT surrounded by the recording level of (1), and (b) driving the laser diode based on the recording data from the recording data generating circuit and the designated power. An LD modulation circuit, and (c) an optical head that records a signal on a medium by driving the LD modulation circuit and reproduces the signal recorded on the medium.
(D) comparing means for comparing the amplitude Va of the reproduction signal corresponding to the 1nT recording level signal with the amplitude Vb of the reproduction signal corresponding to the 1nT erasing level signal; and (e) the output from the comparing means. It is characterized by comprising a control device for calculating an optimum recording power and instructing the modulation circuit to the recording power.

The comparison means is (f) the recording power Pw.
Means for measuring at least one set of amplitude Va and amplitude Vb of the reproduction signal with respect to and storing it in a memory;
(G) From the measured value, the recording power Pw is defined as an independent variable, the ratio Va / Vb of the amplitudes Va and Vb, or the difference Va-.
Vb as a dependent variable, and means for obtaining a primary or quadratic approximate expression between the Pw and the Va / Vb or Va-Vb. As a result, the recording power at which Va / Vb or Va-Vb becomes a constant value can be easily obtained.

Further, the comparison means includes a division circuit for calculating the ratio of the amplitude Va and the amplitude Vb, and the recording power is set by the control device so that the output of the division circuit becomes a constant value. As a result, the procedure for obtaining a first-order or second-order approximation formula is not required, and the number of system software (firmware) steps in the device can be reduced and the number of required memories can be reduced.

Further, the comparison means includes a subtraction circuit for calculating a difference between the amplitude Va and the amplitude Vb, and the recording power is set by the controller so that the output of the subtraction circuit becomes a constant value. Even if it does so, a procedure for obtaining a first-order or second-order approximation formula is unnecessary, and the number of steps of system software (firmware) in the device can be reduced and the number of required memories can be reduced.

Here, the recording level is a level at which the laser power is high when the laser power is applied in pulses, for example, high level F, G as shown in F part of FIG. 7A or FIG. 7B. If there are two or more steps, it means all of them. The erasing level means 0 or a low level near the pulse of the laser power.

[0015]

When the short run length signal on the recording side surrounded by the long run length is recorded, the reproduced signal can be regarded as a solitary wave. Therefore, this signal reflects the optical resolution of the transmission system, especially the optical head.

On the other hand, when a short run length signal on the erasing side surrounded by a long run length is recorded, thermal interference from a recording mark before the short run length affects in the recording process, Since the recording of the next mark starts when the temperature of the recording medium has not completely decreased, the gap between marks corresponding to a short run length is, as a result, compared to when there is no thermal interference. It works in the direction of shortening. Therefore, the reproduction signal amplitude corresponding to this portion is reduced due to the influence of thermal interference as compared with the case of reproducing the solitary wave.

In order to prevent the reproduction signal amplitude from decreasing due to thermal interference, the recording power is reduced, or the pulse width of the recording pulse corresponding to the long run length on the recording side before the short run length on the erasing side is shortened. However, when the recording power is reduced, the amplitude of the reproduction signal corresponding to the short run length on the recording side surrounded by the long run length becomes small. That is, the above-mentioned amplitudes Va and Vb have a reciprocal relationship with the recording power, and there is a recording power that balances both.

According to the present invention, the amplitude V of the aforementioned reproduction signal is
Since a and Vb are obtained and the laser power is set so that the ratio or difference becomes a constant value, a signal with a short run length on the recording side surrounded by a long run length on the erasing side (for example, memory "1" , Or a signal with a short run length on the erasing side surrounded by a long run length on the recording side (for example, corresponding to memory “0”) can be accurately reproduced. Moreover, since the laser power can be set according to the material of the optical disc and the environmental temperature, accurate reproduction can always be performed.

In the PWM recording method, as a method of detecting a mark edge, there is a method of setting a slice level for a reproduction signal and detecting a point where the reproduction signal crosses the slice level as a mark edge. When NRZ recording code is used for recording random data, the average value of the amplitude is between the erasing level for a long run length and the recording level for a long run length, so that Va / Vb = 1. By setting the recording power, the maximum phase margin in the detection circuit system can be obtained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the recording power setting device for an optical disk device of the present invention will be described with reference to the drawings.

Here, as an example, the period of the clock frequency of the recording data is set to T = 40 nanoseconds, and 8Tl-2Th-8
A case where a repetitive signal of Tl-8Th-2Tl-8Th is recorded at a position with a radius of 30 mm will be described. The rotation speed of the disk is 3000 rpm. The lowercase letter after the T is l
Indicates that the laser power corresponding to the erasing level is low and h indicates that the laser power corresponding to the recording level is high.

FIG. 1 is a block diagram of an apparatus showing an embodiment of a recording power setting apparatus portion of an optical disk apparatus of the present invention, FIG.
Is a block diagram of an apparatus showing another embodiment of the recording power setting device portion of the optical disk device of the present invention, FIG. 3 is a diagram showing a recording waveform and a reproducing waveform, and FIG. 4 is an amplitude V of the recording power and the reproducing waveform.
FIG. 5 shows the relationship between a and Vb. FIG. 5 shows the recording power and Va / V.
FIG. 6 is a diagram showing the relationship between the amplitude of the reproduced waveform and 1/2 of the recording level, FIG. 7 is a waveform which is another embodiment of the recorded waveform, and FIG. 8 is the amplitude Va. A flowchart of one embodiment for setting the optimum laser power from the value of Vb, FIG. 9 is a flowchart of another embodiment for obtaining the relationship between the amplitudes Va and Vb, and FIG. 10 is for obtaining the difference between Va and Vb and comparing with the reference value. 2 is a block diagram showing a second embodiment of the recording power setting device portion having a comparing means, FIG. 11 is a diagram showing a waveform of a gate signal input to obtain amplitudes Va and Vb of a reproduced waveform, and FIG. 12 is Va and Vb. The third part of the recording power setting device portion having a comparing means for obtaining the ratio of
It is a block diagram which shows an Example.

In FIG. 1, a control device (hereinafter referred to as CPU) 6 instructs the recording data generating circuit 1 to generate the recording pattern, and the CPU 6 designates the data generated by the recording data generating circuit 1. Based on the recording power
The LD modulation circuit 2 drives the laser diode mounted on the optical head 10 to record on the optical disc 9.

The information recorded on the optical disk 9 passes through the optical head 10 again to become an electric signal, which is amplified by the reproducing amplifier 3 and then converted into digital data by the AD converter 4 and stored in the memory 5. . CPU6
Based on the data stored in the memory 5, arithmetic processing is performed to set the optimum recording power.

Next, a method of setting the optimum recording power will be described using an actual waveform.

At the time of recording, as described above, the LD modulation circuit 2
3A, for example, as shown in FIG. 3A, a laser beam modulated in binary, that is, a run length signal having a short recording level and a run length having a long recording level sandwiched between run lengths having a long erasing level. The optical head 10 irradiates the disk 9 with a laser beam modulated into a run-length signal having a short erasing level sandwiched between the lengths, and information is recorded on the optical disk 9.

When this signal is reproduced, a reproduction signal as shown in FIG. 3 (b) is obtained from the reproduction amplifier 3, and this is converted into digital data by using the AD converter 4 at a sufficiently high sampling frequency. And store it in memory.

When the data for at least one repetition is stored in the memory, the CPU 6 determines that the differential value of the waveform data is 0.
Then, the peak position and the voltage level at that time are calculated. Then, from the inclination and the polarity of the reproduced waveform near the peak, the respective peak positions are A, B, C and D.
Of the amplitudes Va and Vb
Find the value of.

At the time of waveform processing, accuracy is improved by performing smoothing using a digital filter.

By repeating the above operation while changing the recording power, the relationship shown in FIG. 4 is obtained.

Further, based on the data shown in FIG.
For example, using an algorithm such as the least squares method, Va /
The result of having calculated the value of Vb is shown in FIG. Va and Vb
In addition to Va / Vb, (Va-Vb) or the like can be used for the comparison.

Here, considering the noise jitter at the time of reproduction, it is considered that the reproduction signal has the optimum recording power such that Va = Vb. However, if the recorded data consists of a pulse train of completely random length, NRZ
In the modulation method (PWM recording), the average value of the binarized signal has a level of ½ of the amplitude (the temporal duty is 50%). Therefore, it is most ideal to set the slice level at the time of detecting a signal to (recording level-erasing level) / 2. However, if the amplitude level of the reproduction signal is partially smaller than 1/2 as shown in FIG. 3B, an error will occur, so at least Va and Vb will be (B-
A) / 2 must be greater than (see FIG. 6). From this point of view, when considering the fluctuation of the recording power, it is advantageous to use a slightly larger power as the recording power in the combination of the medium and the drive. As a result, as shown in FIG.
The optimum recording power when ＝ Vb is 7.3 mw, but by giving the recording power a little higher than that (for example, 7.5 mw), it is possible to give an equivalent margin to the occurrence of an error with respect to the vertical fluctuation of the recording power. You can Now
a = b (see FIG. 6), that is, Va = Vb (60 in FIG. 5)
0 mV) is considered the optimum condition, the power range that can be used without error is signal amplitude (BA) = 1000 mV,
It can be seen from FIG. 4 that when (EA) = 500 mV, it is 7 to 8 mw.

On the other hand, when the temperature changes, for example,
After performing this test recording, the temperature inside the drive rises as the usage time elapses, and the recording sensitivity of the medium improves, so reduce the recording power to reduce the effect of temperature rise. There is also a possibility.

As described above, the optimum recording power is simply considered to be Va = Vb, but considering the margin including the medium and the drive, if the power different from Va = Vb is optimum. However, it is necessary to make a comprehensive judgment based on the medium and drive. Therefore, Va / Vb or Va is determined by comprehensive judgment of such environmental conditions.
The value of -Vb is set, and the laser power is set so as to be that value.

However, when the NRZ recording code is used as the modulation method and random data is recorded, the average value of the amplitude is between the erasing level for a long run length and the recording level for a long run length, Va / V.
It is preferable to set the recording power so that b = 1 because the maximum phase margin can be obtained.

In the above example, the recording power and Va / V
The relationship of b is approximated by a straight line, and if it is confirmed that the relationship between Va / Vb and the recording power can be expressed by a linear relationship,
With respect to the disc, it is possible to set the optimum recording power with high accuracy by measuring Va / Vb for at least two recording powers.

Further, in the above-mentioned embodiment, as the recording waveform, as shown in FIG. 3A, the continuous run waveform was used for the portion of long run length, but as shown in FIG. By adopting a method of using a set of divided pulses (a so-called pulse train recording method), it is possible to avoid the temperature of the medium from becoming a certain temperature or higher at the time of recording, so that the influence of thermal interference is reduced. There is an effect. In addition, as shown in FIG. 7B, the first pulse is set to have a longer power and a lower power than those of the other pulses (the recording level is set to two steps), so that
The symmetry at the trailing edge is improved, and the error rate during signal reproduction can be reduced.

Further, in the above-described embodiment, the run length of the recorded data is 8T and the short run length is 2T. However, in general, the long run length is 2nT or more and the short run length is 2nT, where n is a positive integer. By setting the length to 1 nT, the recording signal and the erasing signal can be recorded separately. The recording pattern used in the present invention needs to include a short pulse in order to sufficiently reflect the influence of optical resolution and thermal interference, and the shorter the length, the greater the influence. The shorter the shorter pulse is, the more preferable as the recording data for trial writing. for that reason,
It is preferable that the length of 1 nT is equal to the minimum run length in the modulation method used in the optical disc device in which the optical disc for recording is mounted.

Further, even if the length of the erasing level or recording level surrounding 1nT is different from before and after the level signal of 1nT, if the length is 2nT or more, the influence on the short pulse is sufficiently detected. can do.

Further, in the above embodiment, the output of the reproducing amplifier 3 is directly input to the AD converter. However, as shown in the configuration diagram of another embodiment in FIG. It is input to the peak detection circuit 7 composed of a bottom hold circuit, and in the peak detection circuit 7, A, B,
It is also possible to detect the C and D levels and set the optimum recording power from the data. That is, the output from the reproduction amplifier is the peak detection circuit 7 and the gate generation circuit 8.
Sent to the same time. In the gate generation circuit, the reproduction waveform of 2
A gate signal corresponding to the portion corresponding to T is generated.

First, the peak detection circuit 7 detects and holds the peak value of the reproduction signal, that is, B without using the gate signal g, and sends it to the AD converter 4 according to the instruction of the CPU 6. The digital value output from the AD converter 4 is stored in a predetermined address of the memory 5 together with the recording power value. The bottom value A is also stored in the memory 5 by the same procedure.

Next, the peak detection circuit 7 detects and holds the peak value C of the portion corresponding to 2T of the reproduced waveform by using the gate signal g according to the instruction of the CPU 6, and sends it to the AD converter 4. This value is stored in a predetermined address of the memory 5, like A and B.

Finally, using the gate signal g, the bottom value D of the portion corresponding to 2T is stored in a predetermined address of the memory 5.

The CPU 6 repeats the above operation for a plurality of recording powers, obtains the relationship between the recording powers and Va / Vb based on the data stored in the memory 5, and calculates Va / Vb.
The optimum recording power at which Vb becomes constant is calculated.

Next, the means for comparing the amplitude values Va and Vb of the reproduced signal will be described in more detail with a concrete example.

[Embodiment 1] FIG. 8 shows a flow chart of an embodiment of means for calculating and setting the optimum laser power by the control device 6 based on Va and Vb obtained in the circuit of FIG. 1 or 2. The circuit configuration of this embodiment is shown in FIG.
The description is omitted because it is the same.

As shown in FIG. 8, first, the disc type is determined by the disc type discriminating means, that is, the disc material, or the disc type is determined in advance by using a reference measuring machine.
Information such as recording power under a predetermined recording condition (rotation speed, etc.) is read. Next, the center power P of the test recording
The central power Pc is set by the setting means of c. Next, the change amount ΔP of the test recording power is set by the test recording power change amount setting means. Then, the test recording point number setting means sets the recording point number N. After that, the counter was reset and the recording power increased by one rank i =
i + 1 is measured, and it is discriminated by the discriminating means whether i is larger than N. If i> N, the recording power Pw (i) is set to Pc-ΔP + {2ΔP / by the recording power setting means.
(N-1)} * (i-1). After that, recording and reproducing with a test pattern, Va (i), Vb
After measuring (i), Pw (i), Va (i), Vb
Store (i) in the memory 5. When the number of the measurement data becomes larger than N, it is judged by the judging means whether i is larger than N.
es, and Pw is calculated by the calculating means as independent variables Va, V
The constants A and C of the regression equation that satisfy Pw = A (Va / Vb) + C are calculated using b as a dependent variable, and the optimum recording power Pw = A + C when Va / Vb = 1 is obtained, and the process ends. This calculation can be performed using an algorithm such as the least square method. Also, Pw and Va / Vb
The approximate expression for and may be a quadratic expression instead of a linear expression.

In the present embodiment, recording and reproduction are performed simultaneously, but the sector or track on which test recording is to be performed is previously determined to be 1: 1 with respect to the recording power, and the first
As a step, only recording is performed by changing the power, and as a second step, only reading is performed.
It is also possible to take a two-stage stance of measuring.

[Embodiment 2] FIG. 9 shows a flow chart of still another embodiment of means for comparing Va and Vb.
In this example, (Va-Vb) or Va / Vb
Is calculated by a circuit, and an example of the circuit is shown in FIG.

Also in this embodiment, the basic configuration except the calculation circuit is the same as that of the circuit of FIG. 1, and the flow chart is the same as that of the reference power Vref except for the center power.
The procedure is the same as that of the first embodiment up to the point where the counter is reset, the i = i + 1th data is measured, and the determination means determines whether i is larger than N. In the present embodiment, if i> N, the test recording power change amount ΔP is returned to, and if i> N, the recording power Pw (i) is set to Pc +.
{2ΔP / (N-1)} × (i-1) is set, recording and reproduction are performed with a test pattern, and Va (i), Vb
After measuring (i), the voltage of Va-Vb is set to the reference voltage V
Compare with ref. It is determined whether the output of this comparator is below a certain value, and if it is below a certain value, the laser power is determined. The reference voltage is set to a predetermined value according to the type of disc. Although the center power is fixed in the flowchart of FIG. 9, the center power (Pc) can be changed when i> N in order to avoid an infinite loop when i> N.

FIG. 10 shows an example of a circuit for measuring Va and Vb according to the present embodiment and comparing the difference between them with a reference voltage. FIG. 11 shows the waveform of the gate signal at that time. In the circuit of FIG. 10, the recording data generation circuit 1, the LD modulation circuit 2, the medium 9, the optical head 10, the reproduction amplifier 3, the AD converter 4, and the control device 6 have the same configuration as in FIG. The output from the reproduction amplifier is guided to the peak / bottom hold circuit 11, and the peak / bottom hold circuit 11 holds the values of A, B, C, and D shown in FIG. 11 based on the signal of the gate generation circuit 8. Then, through the internal arithmetic circuit, Va (C-
A) and Vb (B-D) are output.

That is, by setting a constant slice level above and below the reproduced signal and generating the gate signal Q shown in FIG. 11, and using this signal to hold the peak and bottom values of the reproduced signal, the value C is obtained. , D can be obtained. The values B and A can be obtained by holding the peak and bottom values of the reproduction signal using the gate signal P (inversion of the polarity of Q). Therefore, depending on the computing unit, CA (=
The values of Va) and BD (= Vb) can be output.

The peak / bottom hold circuit 11 is a CPU
The sampling of A, B, C, and D is started by the instruction of 6, and the CPU 6 receives the value obtained by AD-converting the output of the comparator 13 at a time when the outputs of Va and Vb can be obtained.

Since the comparator 13 compares with a predetermined reference voltage, it is possible to set the recording power to the optimum power by controlling the recording power so that the output of the comparator 13 becomes a certain value or less. it can.

[Embodiment 3] Va and V for obtaining the optimum recording power of the optical disk device of the present invention based on FIG.
Another example circuit for comparing b will be described. Example 2
Compares the value of Va-Vb with the reference voltage, the present embodiment takes a ratio of Va and Vb and compares the value with a constant value.
Va and Vb obtained by 11 are put in the dividing circuit 15, and the value and the reference value are compared by the comparator 13. Since other configurations are the same as those in the second embodiment, the description thereof will be omitted. Also in this embodiment, a constant relationship between Va and Vb can be obtained, and the optimum recording power can be easily set.

Further, in the example of FIGS. 10 and 12, the comparator 13 is provided to compare with the output of the reference voltage generating circuit 12, but the output of the arithmetic unit 14 or 15 is directly input to the AD converter 4, The power at which the output is within a certain range can be set as the optimum recording power.

[0057]

According to the present invention, the optimum recording power can be accurately obtained, and recording can be performed at the center of the recording power range of the apparatus, so that the reliability of the apparatus is improved.

Although the optimum recording power changes depending on the radial position, the optimum recording power is obtained in advance in the inner and outer circumferences according to the above method, and is linearly interpolated with the recording power in the inner and outer circumferences or proportional to the route of the radial position. By performing the interpolation, the recording power at any position on the disc can be obtained.

Further, since the optimum recording power varies depending on the ambient temperature and the type of the disk, the optimum recording power is determined by the above method at the time when the disk is inserted into the optical disk device and at a constant time during operation. By resetting, stable recording / playback operation is always possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a recording power setting device portion of an optical disk device of the present invention.

FIG. 2 is a configuration diagram of another embodiment of the recording power setting device portion of the optical disk device of the present invention.

FIG. 3 is a diagram for explaining the operation of the present invention,
(A) shows a recording waveform and (b) shows a reproduction waveform.

FIG. 4 is a diagram for explaining the operation of the present invention, showing the relationship between the recording power and Va, Vb.

FIG. 5 is a diagram for explaining the operation of the present invention and is a diagram showing the relationship between recording power and Va / Vb.

[FIG. 6] Magnitude of reproduced waveform and 1/2 of recording level
It is a figure explaining the relationship of.

FIG. 7 is a waveform diagram of another example of the recording waveform.

FIG. 8 is a flowchart of an example of setting an optimum laser power based on the values of amplitude Va and Vb of a reproduced waveform.

FIG. 9 is a flowchart of another embodiment for setting the optimum laser power based on the values of the amplitude Va and Vb of the reproduced waveform.

FIG. 10 is a configuration diagram of a recording power setting device portion having a comparison means for obtaining a difference between Va and Vb and comparing the difference with a reference value.

FIG. 11 is a diagram showing a waveform of a gate signal input to obtain amplitudes Va and Vb of a reproduced waveform.

FIG. 12 is a configuration diagram of a recording power setting device portion having a comparison unit that obtains a ratio of Va and Vb and compares it with a reference value.

[Explanation of symbols]

 1 recording data generation circuit 2 LD modulation circuit 3 reproduction amplifier 4 AD converter 5 memory 6 CPU 7 peak detection circuit 8 gate generation circuit 9 optical disk 10 optical head g gate signal

[Procedure amendment]

[Submission date] May 13, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

Further, in the above-described embodiment, the run length of the recorded data is 8T and the short run length is 2T. However, in general, the long run length is 2nT or more and the short run length is 2nT, where n is a positive integer. By setting the length to 1 nT, the recording level signal and the erasing level signal can be recorded separately. The recording pattern used in the present invention needs to include a short pulse in order to sufficiently reflect the influence of optical resolution and thermal interference, and the shorter the length, the greater the influence. The shorter the shorter pulse is, the more preferable as the recording data for trial writing. Therefore, it is preferable that the length of 1 nT is equal to the minimum run length in the modulation method used in the optical disc device in which the optical disc for recording is mounted.

Claims (7)

[Claims] 1. A method for setting the power of laser light at the time of recording of an optical disk device for recording binary digital data on a medium by modulating the intensity of the laser light at the time of recording, wherein As a recording signal, with respect to the clock period T of the recording signal, with n as a positive integer, a recording level signal of 1 nT surrounded by erasing levels of 2 nT or more in the front and rear and a 1 nT recording level signal surrounded by 2 nT or more in the front and rear respectively. NRZ consisting of repetition of erase level signal
Data is recorded, the reproduction signal amplitude Va corresponding to the 1nT recording level signal and the reproduction signal amplitude Vb corresponding to the 1nT erasing level signal are measured for a plurality of different recording powers, and each measured recording is performed. A method for setting the recording power of an optical disk device, characterized in that an optimum recording power is obtained from the magnitude relationship between Va and Vb in power. 2. The recording power according to claim 1, wherein the recording laser pulse corresponding to the recording level signal of 2 nT or more is a set of a plurality of divided pulses partially or entirely. Setting method. 3. The recording power setting method according to claim 1, wherein the length of the erasing or recording level surrounding the 1 nT is different before and after the level signal of 1 nT. 4. An optical disk device comprising a recording power setting device for optimizing the intensity of a laser beam and recording binary digital data on a medium by modulating the intensity of the laser beam at the time of recording. The recording power setting device includes: (a) a clock cycle T of a recording signal of laser power
On the other hand, recording in which a repetitive signal of a recording level signal of 1 nT surrounded by erasing levels of 2 nT or more in the front and rear and an erasing level signal of 1 nT surrounded by recording levels of 2 nT or more in the front and back is generated, where n is a positive integer. A data generation circuit, (b) an LD modulation circuit for driving a laser diode based on the recording data from the recording data generation circuit and the designated power, and (c) a signal to a medium by driving the LD modulation circuit. An optical head for recording and reproducing a signal recorded on a medium, and (d) an amplitude Va of a reproduction signal corresponding to the recording level signal of 1nT and an amplitude Vb of a reproduction signal corresponding to the erasing level signal of 1nT. And (e) a controller for calculating an optimum recording power from the output from the comparing means and instructing the modulation circuit of the recording power. Consisting of an optical disk device. 5. The comparing means comprises (f) the recording power P.
a means for measuring at least one set of the amplitude Va and the amplitude Vb of the reproduction signal with respect to w and storing them in a memory;
(G) From the measured value, the recording power Pw is an independent variable,
The ratio Va / Vb of the amplitudes Va and Vb or the difference Va-Vb
With Pw and Va / Vb or Va as a dependent variable
5. The optical disk device according to claim 4, further comprising means for obtaining a first-order or second-order approximation expression with respect to −Vb. 6. The comparison means includes a division circuit for calculating a ratio between the amplitude Va and the amplitude Vb, and the controller sets the recording power so that the output of the division circuit becomes a constant value. The optical disk device according to claim 4, wherein 7. The comparison means comprises a subtraction circuit for calculating the difference between the amplitude Va and the amplitude Vb, and the controller sets the recording power so that the output of the subtraction circuit becomes a constant value. The optical disk device according to claim 4, wherein