JP4436986B2 - Optical disc apparatus and recording power determination method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus, and more particularly to a recording power setting technique suitable for data recording in an optical disc apparatus that records information by irradiating an optical disc medium with laser light.
[0002]
[Prior art]
In recent years, optical disk devices have been actively developed as means for recording and reproducing large amounts of data, and approaches for achieving higher recording density have been made. There is a phase change type optical disk device that uses a reversible state change.
[0003]
In a phase change type optical disc apparatus, a mark (amorphous portion) is formed on an optical disc medium by irradiating the optical disc medium with a semiconductor laser with two powers, a peak power for amorphizing the crystal portion and a bias power for crystallizing the amorphous portion. ) And a space (crystal part) between the marks.
[0004]
Since the reflectance differs between the mark and the space, the recorded signal is read out using the difference in reflectance during reproduction.
[0005]
FIG. 10 shows a configuration of a phase change type optical disc apparatus in a conventional example. In FIG. 10, the optical disk apparatus includes an optical head 1002, a reproducing unit 1003, a reproduction signal quality detecting unit 1004, an optimum recording power determining unit 1005, a recording unit 1006, a laser driving circuit 1007, and a recording power setting unit 1008.
[0006]
FIG. 11 is a track configuration diagram of the optical disc 1001 in the conventional example. The optical disc 1001 has recording areas on both the groove-shaped track (groove track 1101) and the track between the grooves (land track 1102), and the groove track and the land track are alternately connected to form a continuous spiral. Optical disc.
[0007]
When the optical disc 1001 is newly installed in the optical disc apparatus, the optical disc apparatus performs trial recording on a predetermined area of the disc 1001 to thereby optimize the laser power applied to the disc 1001 for data recording. Set.
[0008]
For this reason, when the optical disc 1001 is loaded into the optical disc apparatus, the optical head 1002 moves to an area for setting the optimum irradiation power after completion of predetermined operations such as disc type identification and rotation control.
[0009]
As the power to be determined, there are a peak power and a bias power in the phase change type optical disc apparatus. Here, a method for determining the peak power will be described.
[0010]
First, the recording power setting means 1008 sets initial values of peak power and bias power in the laser drive circuit 1007. At this time, the power for recording the land track is equal to the power for recording the groove track.
[0011]
Subsequently, a signal for recording one land track and one groove track from a predetermined position is sent from the recording means 1006 to the laser driving circuit 1007 and recorded by the optical head 1002. At this time, the output light of the semiconductor laser, which is a constituent element of the optical head 1002, is collected as a light spot on the optical disc 1001, and a recording mark corresponding to the emission waveform is formed.
[0012]
When the land track and groove track recording is completed, the semiconductor laser of the optical head 1002 emits light with the reproduction power, reproduces the recorded track, and the signal 1009 changes depending on the presence or absence of a recording mark on the optical disc 1001 as a reproduction signal. Is input to the playback means 1003. The reproduction signal 1009 is subjected to reproduction signal processing such as amplification, waveform equalization, binarization, etc. by the reproduction means 1003, and the signal 1010 is input to the reproduction signal quality detection means 1004.
[0013]
The reproduction signal quality detection unit 1004 detects the signal quality of the signal 1010 and inputs the detection result to the optimum recording power determination unit 1005.
[0014]
Here, the reproduction signal quality detection means 1004 detects the BER (byte error rate) when the recorded signal is reproduced. The BER detected at this time is the average value of the reproduced tracks. FIG. 12 shows the relationship between peak power and BER.
[0015]
In FIG. 12, the horizontal axis is peak power, and the vertical axis is BER. If the reproduction conditions are equal, generally, the smaller the BER, the more accurate recording is performed. Therefore, the detection result is “OK (good)” when the BER is below a certain threshold, and the detection result is “NG (defective)” when the detection result is higher than that.
[0016]
The optimum recording power determining means 1005 determines the recording power (peak power) according to the flowchart shown in FIG. 13, for example.
[0017]
When the optical head moves to the irradiation power setting area on the optical disc 1001 (S101) and the initial value of the recording power is set (S102), data is recorded in the irradiation power setting area on the optical disc 1001 with the recording power, The recorded data is reproduced (S103). By detecting the BER of the reproduction signal, the quality of the reproduction signal is detected (S104). From the detection result at that time and the previous detection result, two peak powers when the reproduction signal quality is switched from “OK” to “NG” or from “NG” to “OK” are obtained (S104 to S108). ). When these two peak powers are obtained, the power values are averaged (S109), and a value obtained by adding a predetermined margin is set as the optimum peak power (S110).
[0018]
For example, if the first result by the reproduction signal quality detection means 1004 is “NG”, a peak power larger than the initial power is set (S108). If the first result is “OK”, a peak smaller than the initial power is set. The power is set (S106), and the land track and groove track are recorded and reproduced at the set peak power as in the previous case.
[0019]
If the first result of the reproduction signal quality detection unit 1004 is “NG” (S104) and the second result is “OK” (S107), the optimum recording power determination unit 1005 determines the current peak power and the previous time. The power obtained by adding a certain margin to the average power of the peak power is determined as the optimum recording power (S109, S110).
[0020]
If the first result of the reproduction signal quality detection means 1004 is “OK” (S104) and the second result is “NG” (S105), the optimum recording power determination means 1005 determines the current peak power and the previous time. The power obtained by adding a certain margin to the average power of the peak power is determined as the optimum recording power (S109, S110).
[0021]
[Problems to be solved by the invention]
However, in the above prior art, since the detected BER is an average value in the reproduced track, for example, when a fingerprint is attached to the track portion where the BER is detected, the reproduction error increases, and the detected BER is the original value. As a result, there is a problem that a power higher than the optimum peak power is set.
[0022]
In view of the above problems, the present invention provides an optical disc apparatus capable of obtaining a recording power suitable for data recording even when a fingerprint is attached to a track on which trial recording is performed in order to determine irradiation power at the time of recording, and its An object of the present invention is to provide a recording power determination method.
[0023]
[Means for Solving the Problems]
The method according to the present invention has a plurality of tracks extending in a spiral shape and each track is a laser output power at the time of data recording for an optical disc apparatus that records data on an optical disc comprising a plurality of sectors. It is a method of determining power. The method includes a first step of setting a plurality of recording power values, recording predetermined data in a plurality of sectors in a predetermined area with the recording power of each setting value, and reproducing the data from each sector after data recording. And a second step of detecting the quality of the reproduction signal for each sector, and a set value of the recording power when a predetermined number or more sectors of the reproduction signal quality satisfy the predetermined condition are obtained. Among these, the recording power setting value closest to the recording power setting value when a predetermined number or more sectors of the reproduction signal quality satisfy the predetermined condition cannot be obtained. And a set value of recording power when a predetermined number or more of sectors satisfying a predetermined condition of reproduction signal quality cannot be obtained. Among these, the recording power setting value closest to the recording power setting value when a predetermined number or more of sectors satisfying the predetermined condition for the reproduction signal quality is obtained And the second set value , And determining the recording power based on the first and second set values, and determining the peak power as the recording power, in the third step Then, a value obtained by adding a margin by multiplying the average value of the first set value and the second set value by a certain ratio is determined as the optimum peak power, and the bias power is determined as the recording power. In this case, in the process of obtaining the lower limit value and the upper limit value of the bias power, the first to third steps are respectively executed, and the first set value is obtained in the third step of the process of obtaining the lower limit value. And the average value of the second set value is determined as the lower limit value of the bias power, and in the third step in the process of obtaining the upper limit value, the average value of the first set value and the second set value is Determined as the upper limit of bias power, a value obtained by internally dividing the low and high values in a predetermined ratio is determined as the optimum bias power.
[0026]
As playback signal quality, playback signal quality Lare Data or jitter can be detected.
[0027]
In addition, a sector detection result whose reproduction quality satisfies a predetermined defect condition may be excluded from the detection result used for determining the recording power.
[0028]
Further, when recording predetermined data, data different from the previously recorded data may be recorded in each sector.
[0029]
Further, when recording predetermined data, the data recorded in each sector may be once erased and then the predetermined data may be recorded in each sector.
[0030]
An apparatus according to the present invention has a plurality of tracks connected in a spiral shape, and each track is an optical disc device for recording data on an optical disc composed of a plurality of sectors, and has a laser output power at the time of data recording. Setting means for executing a first step for setting a plurality of values of a certain recording power, recording predetermined data in a plurality of sectors in a predetermined area with the recording power of each setting value, and data from each sector after data recording Recording / detecting means for executing the second step of reproducing and detecting the quality of the reproduced signal for each sector, and a recording power setting value when a predetermined number or more sectors of the reproduced signal quality satisfy a predetermined condition are obtained Among these, the recording power setting value closest to the recording power setting value when a predetermined number or more sectors of the reproduction signal quality satisfy the predetermined condition cannot be obtained. And a set value of recording power when a predetermined number or more of sectors satisfying a predetermined condition of reproduction signal quality cannot be obtained. Among these, the recording power setting value closest to the recording power setting value when a predetermined number or more of sectors satisfying the predetermined condition for the reproduction signal quality is obtained And the second set value , And determining means for executing a third step of determining the recording power based on the first and second set values, wherein the determining means determines a peak power as the recording power. In the third step, a value obtained by adding a margin by multiplying an average value of the first set value and the second set value by a certain ratio is determined as an optimum peak power, and the recording is performed. When determining the bias power as the power, in the process of obtaining each of the lower limit value and the upper limit value of the bias power, the first to third steps are respectively executed, and the third step in the process of obtaining the lower limit value. In the third step in the process of determining the average value of the first set value and the second set value as the lower limit value of the bias power and obtaining the upper limit value, The value and the average value of the second setting value, determined as the upper limit of the bias power, a value obtained by internally dividing the low and high values in a predetermined ratio is determined as the optimum bias power.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an optical disc apparatus according to the present invention will be described below with reference to the drawings.
[0032]
(Configuration of optical disk device)
FIG. 1 shows the configuration of a phase change optical disc apparatus according to an embodiment of the present invention. The optical disk apparatus is an apparatus for recording and reproducing data with respect to the optical disk 101. As shown in FIG. 1, the optical head 102, reproducing means 103, reproduced signal quality detecting means 104, optimum recording power determining means 105, recording Means 106, a laser drive circuit 107, and a recording power setting means 108.
[0033]
FIG. 2 is a track configuration diagram of the optical disc 101 on which the optical disc apparatus records and reproduces data. The optical disc 101 has recording areas on both the groove-shaped track (groove track 201) and the track between the grooves (land track 202), and the groove track and the land track are alternately connected to form a continuous spiral. Optical disc.
[0034]
(Operation of optical disk device)
When the optical disk 101 is newly mounted on the optical disk apparatus, the optical disk apparatus performs trial recording on a predetermined area of the disk 101, thereby irradiating the disk 101 with an optimum value of the laser power irradiated for data recording. Set.
[0035]
For this reason, the optical disk 101 is mounted on the optical disk apparatus, and after completion of predetermined operations such as disc type identification and rotation control, the optical head 102 moves to an area (irradiation power setting area) for setting the optimum recording power. .
[0036]
The area (irradiation power setting area) is a recording area provided on the innermost or outermost circumference of the disc other than the user area where the user records data.
[0037]
The operation for determining the power during recording will be described below.
In the phase change optical disc apparatus, the power to be determined includes at least peak power and bias power. In the present embodiment, a method for determining peak power will be described first, followed by a method for determining bias power.
[0038]
First, the recording power setting means 108 sets initial values of peak power and bias power in the laser drive circuit 107. The recording power setting means 108 can set various values of recording power. At this time, the power for recording the land track is equal to the power for recording the groove track.
[0039]
Subsequently, a signal for continuously recording one land track and one groove track from a predetermined position is sent from the recording means 106 to the laser drive circuit 107 and recorded by the optical head 102. At this time, the output light of the semiconductor laser, which is a component of the optical head 102, is collected as a light spot on the optical disc 101, and a recording mark corresponding to the emission waveform is formed.
[0040]
When the recording is completed, the semiconductor laser of the optical head 102 emits light at the reproduction power, reproduces the track on which recording was performed, and a signal 109 that changes depending on the presence or absence of the recording mark on the optical disc 101 is input to the reproduction means 103 as a reproduction signal. Is done. The reproduction signal 109 is subjected to reproduction signal processing such as amplification, waveform equalization, binarization, etc. by the reproduction means 103, and the signal 110 is input to the reproduction signal quality detection means 104.
[0041]
The reproduction signal quality detection unit 104 detects the signal quality of the signal 110 and inputs the detection result to the optimum recording power determination unit 105. When the number of sectors of the reproduced land track is substantially equal to the number of sectors of the groove track, the reproduction signal quality detection result at this time is an average reproduction signal quality result of both the land and groove tracks.
[0042]
Here, the reproduction signal quality detection means 104 detects a BER (byte error rate) when the recorded signal is reproduced. FIG. 3 shows the relationship between peak power and BER. In FIG. 3, the horizontal axis represents peak power, and the vertical axis represents BER. If the reproduction conditions are equal, generally, the smaller the BER, the more accurate recording is performed. Therefore, BER is detected for each sector, and when the detected BER is below a predetermined threshold (hereinafter referred to as “error number threshold”), the sector is set to “OK sector (good sector)”, and the detected BER is an error. When the number threshold is exceeded, the sector is defined as “NG sector (bad sector)”.
[0043]
(Peak power determination method)
The optimum recording power determining means 105 determines the optimum recording power according to the flowchart shown in FIG.
[0044]
After the optical head 102 moves to the irradiation power setting area on the optical disc 101 (S11) and the initial value of the recording power is set (S12), the recording power is applied to a plurality of sectors in the irradiation power setting area on the optical disc 101. Data is recorded, and then the recorded data is reproduced from each sector (S13). By judging the quality of the reproduction signal obtained at that time, it is judged whether or not the recording power at that time is sufficient for data recording. The recording power is sequentially changed, a boundary between a recording power sufficient for data recording and an insufficient recording power is searched, and two recording powers that cross the boundary are obtained (S14 to S18). When the recording power at these boundaries is obtained, these values are averaged (S19), and a margin is added by multiplying the average value by a certain ratio (S20) to obtain the optimum recording power.
[0045]
Here, whether or not the recording power is a sufficient value for data recording is determined as follows. That is, for one recording power, the BER of the reproduction signal is detected for each sector, the sector having the BER equal to or higher than a predetermined value (error number threshold) is set as the NG sector, and the number of NG sectors is counted. When the number of NG sectors is equal to or greater than a threshold (hereinafter referred to as “sector threshold”), the recording power is assumed to be an insufficient value for data recording, and is sufficient when the number is less than the sector threshold. In the following description, the sector threshold value is half the total number of sectors for which trial recording is performed. That is, conventionally, it is determined whether the laser output power of the test recording is sufficient based on the BER for each track. In the present embodiment, the BER is detected for each of a plurality of sectors. It is determined whether each sector is OK (good) or NG (bad). When the number of NG sectors is equal to or greater than a predetermined number (sector threshold), it is determined that the recording power at that time is insufficient. When the number of sectors is less than a predetermined number (sector threshold), it is determined that the recording power at that time is sufficient.
[0046]
For example, in the first detection result by the reproduction signal quality detection means 104, if more than half of the total number of sectors in the irradiation power setting area are NG sectors (YES in S14), a peak power larger than the initial power is obtained. If it is set (S18) and more than half of the sectors are OK (NO in S14), a peak power smaller than the initial power is set (S16), and the land track and groove are set with the set peak power as in the previous time. Track recording and reproduction are performed (S13).
[0047]
If more than half of the sectors are OK sectors in the second result of the reproduction signal quality detection means 104 (NO in S14), and more than half of the sectors are NG sectors in the first result (YES in S15), the optimum The recording power determining means 105 determines a power obtained by adding a certain margin to the average power of the first peak power and the second peak power as the optimum recording power (S19, S20).
[0048]
If more than half of the sectors are NG sectors in the second result of the reproduction signal quality detection means 104 (YES in S14), and more than half of the sectors are OK sectors in the first result (YES in S17), the optimum The recording power determining means 105 determines a power obtained by adding a certain margin to the average power of the first peak power and the second peak power as the optimum recording power (S19, S20).
[0049]
If the second result of the reproduction signal quality detection means 104 is more than half of the sectors are OK sectors (NO in S14), and if the first result is more than half of the sectors are OK sectors (NO in S15). A power smaller than the peak power recorded for the second time is set (S16), recording and reproduction are performed with this peak power, and the reproduction signal quality is detected (S13). If more than half of the sectors in the third result of the reproduction signal quality detection means 104 are NG sectors (YES in S14), the optimum recording power determination means 105 determines the average power of the second peak power and the third peak power. Is determined to be the optimum recording power (S19, S20).
[0050]
With reference to FIG. 5, a description will be given of how to obtain the boundary recording power for setting the optimum recording power.
[0051]
FIG. 5 is a table showing a list of results when recording is performed on eight sectors while changing the setting value of the recording power and the number of errors (BER) of the reproduction signal is measured. In FIG. 5, (a) shows the result when no fingerprint is attached on the surface of all sectors, (b) shows the result when the fingerprint is attached to sector 0, and (c) shows sector 0 and sector 1. This is a result when a fingerprint is attached to the. Here, the error threshold for the track in the conventional method is 80, and the error threshold for each sector in the method of this embodiment is the error threshold (80) for the entire track as the number of playback sectors (8). The divided value (10) is set.
[0052]
The number of errors (BER value) and the number of NG sectors are shown at the right end of the table. The number of errors is the sum of errors at each set power. The number of NG sectors is the total number of NG sectors when the error number threshold of each sector is 10. In the conventional method for obtaining the BER in units of tracks, the total error in each set power is obtained. For this reason, the number of errors increases as the set power decreases in order of P0, P1, P2,. For example, in the example of FIG. 5A, in the conventional method (for example, the error number threshold is 80), P3 and P4 (indicated by *) are detected as powers around the error number threshold (80) value. The optimum recording power is determined based on the recording power value. On the other hand, in the method of the present embodiment, the error number threshold (10) is compared for each sector, and the power before and after the number of NG sectors exceeds the sector threshold (4 = 8/2) is set to P3 and P4 ( *) Is detected, and the optimum recording power is determined based on these recording power values.
[0053]
Here, in FIG. 5A, the recording power set by the conventional method and the method of this embodiment is equal. This is obtained by dividing the error number threshold (80) in the conventional example by the number of sectors (8) to obtain the error number threshold (10) of each sector of the present embodiment, and half (4) of the total number of sectors is NG sector. This is due to the detection of the power. That is, near the recording power to be detected, the number of errors in each sector is almost the value obtained by dividing the conventional error number threshold by the number of sectors, and about half of all sectors are considered to exceed the error number threshold. Because.
[0054]
In FIG. 5B when the fingerprint is attached to sector 0, the number of errors increases with sector 0. Therefore, in the conventional method, the power before and after the number of errors is the threshold value (80) is P2 and P3. A higher recording power is set than when no fingerprint is attached (in the case of (a)). On the other hand, in the method of the present embodiment, the same recording power as when no fingerprint is attached is set. Further, in FIG. 5C where fingerprints are attached to sector 0 and sector 1, the number of errors increases depending on sector 0 and sector 1, so that the number of errors is around the threshold (80) in the conventional method. The power is P1 and P2, and a higher recording power is set compared to when the fingerprint is attached only to sector 0 (in the case of (b)). On the other hand, in the method of the present embodiment, the same recording power as that when the fingerprint is not attached (in the case of (a)) is set.
[0055]
That is, in the conventional method, since the total number of errors per track is taken into account, the larger the number of errors due to fingerprint attachment, the greater the deviation of the set recording power from the original set value. . On the other hand, in this embodiment, it is determined whether each sector is “NG” or “OK”. For example, in FIG. 5B, three sectors out of seven sectors excluding sector 0 are “ In FIG. 5C, two of the six sectors excluding sector 0 and sector 1 are “NG” due to the recording characteristics. Therefore, it is substantially equivalent to excluding a sector to which a fingerprint is attached, and the influence of the fingerprint can be limited. In FIG. 5, the number of sectors to be reproduced has been described as eight. However, as the number of sectors increases, the influence of fingerprints and the like is smaller. For example, in the case of 16 sectors or more, the set recording power is almost affected by fingerprints. Absent.
[0056]
As described above, when trial recording is performed on a plurality of sectors prior to user data recording, the reproduction signal quality is detected for each recorded sector, and the number of errors (BER) indicating the reproduction signal quality is equal to or less than a threshold value. At that time, the sector is set as an OK sector. Then, the recording power at the boundary where the number of NG sectors changes from a predetermined number or more to less than the predetermined number or the number of OK sectors changes from the predetermined number or more to less than the predetermined number is found, and the actual data is based on the recording power. To determine the recording power for recording. Thereby, even if a fingerprint or a flaw is attached to the track area where the test recording is performed, the optimum power can be obtained.
[0057]
Note that, based on the detection result of the number of errors per sector (BER), a sector that is considered to be particularly bad compared to other sectors is considered unsuitable for use in determining recording power. Therefore, it may be excluded from the NG sector in advance.
[0058]
For example, when the number of errors per sector (BER) is detected and there is a sector whose number of errors is more than a predetermined number (for example, 30) compared to the number of errors in the sector having the smallest number of errors, The number of sectors may be excluded from the number of NG sectors. At this time, the sector number threshold value is set to a value obtained by subtracting the excluded sector number from the total number of reproduced sectors and dividing it by 2. A sector having a relatively large number of errors is considered to have a fingerprint or the like attached thereto, and is unsuitable for use in determining the recording power. Therefore, by excluding this, the recording power can be obtained more accurately.
[0059]
For example, in FIG. 5 (c), sector 0 and sector 1 have 30 more errors than other sectors with respect to the power of P0, so these two sectors were excluded from the NG sector and 2 sectors were subtracted from 8 sectors. 3 which is a value obtained by dividing 6 sectors by 2 is set as a sector number threshold. Even in this case, as in FIG. 5A, P3 and P4 are detected as the boundary power for obtaining the optimum recording power.
[0060]
Further, when the BER for each sector is detected while changing the recording power, if there is a sector having the maximum number of errors for a predetermined number of times (for example, twice or more), the sector may be excluded from the NG sector. . At this time, a value obtained by dividing the number of sectors obtained by subtracting the number of removed sectors from the number of reproduced sectors and dividing by 2 is set as a sector number threshold. This also makes it possible to determine the recording power more accurately.
[0061]
For example, in FIG. 5 (b), sector 0 has more errors than other sectors due to the power of P0 and P1, so this sector is excluded from the NG sector, and 7 sectors obtained by subtracting 1 sector from 8 sectors are divided by 2. The value 3.5 is set as the sector count threshold. Even in this case, as in FIG. 5A, P3 and P4 are detected as the boundary power for obtaining the optimum recording power.
[0062]
Similarly, when the BER for each sector is detected while changing the recording power, there are sectors that are not less than a predetermined number of times (for example, twice or more) and not more than a predetermined order (arranged in order from a sector with a small number of errors). Sometimes the sector may be excluded from the number of NG sectors.
[0063]
For example, in FIG. 5C, sector 0 and sector 1 are the lowest in the number of errors with the power of P0 and P1, so this sector is excluded from the NG sector, and 6 sectors obtained by subtracting 2 sectors from 8 sectors are divided by 2. The value 3 is set as the sector number threshold. Even in this case, as in FIG. 5A, P3 and P4 are detected as the boundary power for obtaining the optimum recording power.
[0064]
In this embodiment, the sector number threshold is half of the number of reproduction sectors. However, the sector number threshold may be determined by other methods as long as the correct recording power can be obtained without the influence of fingerprints or the like. good.
[0065]
In the above description, the error number threshold for each sector is set to a value obtained by dividing the error number threshold for the entire track by the number of reproduction sectors. However, if the correct recording power can be obtained except for the influence of fingerprints and the like. The error number threshold value for each sector may be determined by other methods.
[0066]
(Bias power determination method)
Next, a method for determining the bias power will be described.
Bias power has a narrower power margin for recording user data than peak power. For example, even if the peak power margin is 9 mW to 15 mW and 6 mW, the bias power margin is only 3 mW to 6 mW and 3 mW. .
[0067]
Therefore, in this embodiment, in order to obtain the optimum value of the bias power, after obtaining the lower limit value and upper limit value of the bias power capable of recording user data, the optimum value between the lower limit value and the upper limit value is calculated. Ask for.
[0068]
First, the recording power setting means 108 sets, for example, the peak power and the initial value of the bias power in the laser drive circuit 107 in order to obtain the lower limit value of the bias power. At this time, the power for recording the land track is equal to the power for recording the groove track.
[0069]
Subsequently, a signal for continuously recording one land track and one groove track from a predetermined position on the optical disc 101 is sent from the recording means 106 to the laser drive circuit 107, and is applied onto the optical disc 101 by the optical head 102. Data is recorded. At this time, the output light of the semiconductor laser, which is a component of the optical head 102, is collected as a light spot on the optical disk 101, and a recording mark corresponding to the emission waveform is formed on the optical disk 101.
[0070]
When the recording is completed, the semiconductor laser of the optical head 102 emits light at the reproduction power, reproduces the track on which the recording was performed, and a signal (reproduction signal) 109 that changes depending on the presence or absence of the recording mark on the optical disc 101 is reproduced as a reproduction signal Input to means 103. The reproduction signal 109 is subjected to reproduction signal processing such as amplification, waveform equalization, binarization, etc. by the reproduction means 103, and the signal 110 is input to the reproduction signal quality detection means 104.
[0071]
Here, the reproduction signal quality detection means 104 detects a BER (byte error rate) when the recorded signal is reproduced. FIG. 6 shows the relationship between bias power and BER in a certain sector. In FIG. 6, the horizontal axis is the bias power, and the vertical axis is the BER. If the reproduction conditions are equal, generally, the smaller the BER, the more accurate recording is performed. Therefore, the BER is detected for each sector, the detected BER is compared with a predetermined threshold (error number threshold), and when the detected BER is equal to or less than the error number threshold, the sector is determined to be an OK sector, and the error number threshold is exceeded. Then, the sector is set as the NG sector.
[0072]
The optimum recording power determining means 105 determines the optimum bias power according to the flowchart shown in FIG.
[0073]
In the flowchart of FIG. 7, the lower limit value is obtained from step S41 to step S49, and the upper limit value is obtained from step S50 to step S57. The processing for obtaining the upper limit value and the lower limit value in the above steps is basically the same as the processing in the flowchart of FIG.
[0074]
For example, when obtaining the lower limit value of the bias power, if more than half of the sectors are NG sectors in the first result of the reproduction signal quality detection means 104 (YES in S44), a bias power larger than the initial power is set. If more than half of the sectors are OK (NO in S44), a bias power smaller than the initial power is set (S46), and the land track and groove track are set with the set bias power as before. Is recorded and reproduced (S43).
[0075]
If more than half of the sectors are OK sectors in the second result of the reproduced signal quality detection means 104 (NO in S44), and more than half of the sectors are NG sectors in the first result (YES in S45), the optimum The recording power determining means 105 determines the average of the current bias power and the previous bias power as the lower limit value (S49).
[0076]
If more than half of the sectors are NG sectors in the second result of the reproduction signal quality detection means 104 (YES in S44), and more than half of the sectors are OK sectors in the first result (YES in S47), the optimum The recording power determining means 105 determines the average power of the current bias power and the previous bias power as the lower limit value (S49).
[0077]
If more than half of the sectors are OK sectors in the second result of the reproduction signal quality detection means 104 (NO in S44), and if more than half of the sectors are OK sectors in the first result (NO in S45), 2 A power smaller than the bias power recorded for the second time is set (S46), recording and reproduction are performed with this bias power, and the reproduction signal quality is detected (S43). If more than half of the sectors in the third result of the reproduction signal quality detection means 104 are NG sectors (YES in S44), the optimum recording power determination means 105 sets the average power of the current power and the previous power as the lower limit value. Determine (S49).
[0078]
The upper limit value is similarly obtained (S50 to S57), and the optimum recording power determination means 105 determines, for example, the average value of the lower limit value and the upper limit value as the optimum bias power (S58).
[0079]
Also in determining the bias power, trial recording is performed on a plurality of sectors, the reproduction signal quality is detected for each recorded sector, and when the number of errors is less than or equal to the error number threshold, the sector is determined to be an OK sector, and the error number threshold is exceeded. When the sector becomes an NG sector, the recording power at the boundary where a predetermined number of sectors or more changes from the NG sector to the OK sector or changes from the OK sector to the NG sector is found, and the recording power at this boundary is used. By determining the recording power for actually recording data, the optimum power can be obtained even if fingerprints or scratches are attached to the track on which test recording is performed.
[0080]
When determining the lower and upper limit values, the initial bias power value for determining the upper limit value is made larger than the initial bias power value for determining the lower limit value. By starting from a value close to each limit, the bias power can be optimized in a shorter time.
[0081]
Further, in the present embodiment, the average value of the lower limit value and the upper limit value is determined as the optimum bias power, but for the set optimum power at a place where user data is actually recorded due to, for example, warping of the disc. If the effective power may be very small, a value that internally divides the lower limit value and the upper limit value into 2: 1 may be set as the optimum power. By setting the value obtained by internally dividing the lower limit value and the upper limit value to 2: 1 as the optimum power, the margin on the low power side is increased.
[0082]
(Other possible aspects)
In this embodiment, the playback signal quality detection means 104 detects the BER (byte error rate) when the recorded signal is played back. At this time, errors that occur continuously more than the specified number are counted as errors. If there is no such area, even if there is a recording failure area such as a scratch, these areas can be removed, and the optimum power can be determined more accurately.
[0083]
In this embodiment, the reproduction signal quality detection means 104 detects the BER when the recorded signal is reproduced. However, if the reproduction signal quality can be detected other than the BER, a bit error rate, jitter, or the like may be used. .
[0084]
For example, a case where jitter is detected as the reproduction signal quality will be described. FIG. 8 shows the relationship between peak power and jitter. In FIG. 8, the horizontal axis represents peak power, and the vertical axis represents jitter. FIG. 9 shows the relationship between bias power and jitter. In FIG. 9, the horizontal axis represents bias power, and the vertical axis represents jitter. Jitter is a time lag between the playback signal and the original signal, which occurs due to a decrease in the playback signal amplitude due to insufficient laser beam irradiation power, etc., and decreases when the playback signal amplitude increases. When saturated, the amount of jitter becomes almost constant. That is, if the reproduction conditions are equal, generally, the smaller the jitter, the more accurate recording is performed. Therefore, when the jitter of a certain sector is less than the threshold value, the sector is set as an OK sector, and when the sector exceeds the threshold value, the sector is set as an NG sector.
[0085]
In the present embodiment, one round of the land track and one round of the groove track are used as the continuous recording and continuous playback sections. However, in the optical disk apparatus that performs recording in block units, recording may be performed in block units.
[0086]
Similarly, in the present embodiment, one round of the land track and one round of the groove track are used as the continuous recording and continuous reproduction sections. However, in the optical disk apparatus that performs recording in units of sectors, recording in units of sectors may be used.
[0087]
Further, in this embodiment, the land track has one round and the groove track one round as continuous recording and continuous playback sections, but recording and reproduction may be performed over two or more land tracks or two or more groove tracks. . By recording and reproducing two or more tracks on both tracks, it is possible to absorb the variation of the tracks and determine the optimum power more accurately.
[0088]
Similarly, even when recording is performed in units of blocks, recording and reproduction of two or more land track blocks and two or more groove track blocks may be performed. By recording and reproducing two or more blocks on both tracks, it is possible to absorb the variation between the blocks and determine the optimum power more accurately.
[0089]
Further, when performing continuous recording and continuous reproduction of two or more blocks, if the worst block value as a result of the reproduction signal quality detection means 104 is not adopted, even if there is a recording defective block such as a flaw, the block is excluded. And the optimum power can be determined more accurately.
[0090]
Note that a signal having a pattern different from the recording signal used for the recording may be recorded before recording for detecting the reproduction signal quality. By recording a signal with a different pattern, the component of the previously recorded signal remaining in the recording area is reduced. For example, when the signal is recorded at a lower power than the previous time and sufficient recording cannot be performed, the previously recorded signal is erroneously recorded. And the power optimization can be performed more accurately.
[0091]
Further, before each continuous recording for detecting the reproduction signal quality, the recording may be performed in the area where the continuous recording is performed only with the bias power. By performing the recording only with the bias power, the component of the previously recorded signal remaining in the area is reduced (that is, erased). For example, even if the recording is performed at a lower power than the previous time and sufficient recording cannot be performed, an error occurs. Thus, the previously recorded signal is not reproduced, and the power can be optimized more accurately.
[0092]
In addition, the reproduction signal quality detection unit 104 according to the present embodiment performs the determination for each sector without distinguishing the land track and the groove track, but distinguishes the land track and the groove track and performs the determination for each sector. You can go. By distinguishing the land track and the groove track, when the recording characteristics of the two tracks are different, it is possible to determine a recording power suitable for each track.
[0093]
Also, by reproducing the land track and the groove track separately, it is not necessary to reproduce the other after the recording power of one track is determined, and time for determining the recording power can be saved.
[0094]
Further, the recording power setting means 108 of the present embodiment sets the recording power without distinguishing between the land track and the groove track. However, the recording power may be set by distinguishing between the land track and the groove track. By distinguishing the land track and groove track, when the recording characteristics of both tracks are different, the recording power suitable for each is set as the initial setting power, thereby reducing the number of times the recording power is set, After the recording power of one track has been determined, it is not necessary to record the other, saving time for determining the recording power and reducing deterioration due to repeated recording.
[0095]
In the present embodiment, the optical disk that can be recorded on both the land track and the groove track has been described. However, the same applies to an optical disk that records only one of the tracks.
[0096]
【The invention's effect】
As described above, the optical disk apparatus according to the present embodiment performs test recording in a plurality of sectors prior to user data recording, detects the reproduction signal quality for each recorded sector, and is less than a certain threshold value. The sector is set as an OK sector, and when the sector exceeds the threshold value, the sector is set as an NG sector. At this time, the recording power at the boundary where the number of NG sectors changes from a predetermined number or more to less than the predetermined number, or the number of NG sectors changes from less than the predetermined number to more than the predetermined number, is detected. By determining the recording power for actually recording data using the power, it is possible to accurately obtain a recording power suitable for data recording even when a fingerprint is attached to a track on which test recording is performed.
[Brief description of the drawings]
FIG. 1 is a block diagram of an optical disc apparatus according to the present invention.
FIG. 2 is a diagram showing a track configuration of an optical disc used in an optical disc apparatus according to the present invention.
FIG. 3 is a diagram illustrating the relationship between peak power and BER (byte error rate).
FIG. 4 is a flowchart showing a peak power determination method in the optical disc apparatus according to the present invention.
FIG. 5 is a diagram for explaining a method of determining recording power at two boundaries used for determining optimum recording power.
FIG. 6 is a diagram illustrating the relationship between bias power and BER.
FIG. 7 is a flowchart showing a method of determining bias power in the optical disc apparatus according to the present invention.
FIG. 8 is a diagram illustrating the relationship between peak power and jitter.
FIG. 9 is a diagram illustrating the relationship between bias power and jitter.
FIG. 10 is a block diagram of an optical disc apparatus according to the prior art.
FIG. 11 is a diagram showing a track configuration of an optical disc.
FIG. 12 is a diagram illustrating the relationship between peak power and BER.
FIG. 13 is a flowchart showing a method for determining the recording power of the optical disc apparatus in the prior art.
[Explanation of symbols]
101 optical disc
102 Optical head
103 Reproduction means
104 Reproduction signal quality detection means
105 Optimal recording power determination means
106 Recording means
107 Laser drive circuit
108 Recording power setting means

Claims (10)

A method of determining a recording power which is a laser output power at the time of data recording of an optical disc apparatus having a plurality of tracks connected in a spiral shape and each track recording data on an optical disc comprising a plurality of sectors. ,
A first step of setting a plurality of recording power values;
A second step of recording predetermined data in a plurality of sectors within a predetermined area with a recording power of each set value, reproducing the data from each sector after data recording, and detecting the quality of the reproduction signal for each sector;
Among the recording power setting values when a predetermined number or more of sectors satisfying a predetermined condition for the reproduction signal quality are obtained, the recording power setting value for when a predetermined number or more of the sectors satisfying the predetermined condition for the reproduction signal quality cannot be obtained A first setting value that is the recording power setting value closest to
Of the recording power setting values when a predetermined number or more of sectors satisfying a predetermined condition for reproduction signal quality cannot be obtained, the setting values for recording power when a predetermined number or more of sectors satisfying a predetermined condition for reproduction signal quality are obtained a second set value which is the set value of the nearest recording power,
And determining the recording power based on the first and second set values, and a third step,
When determining the peak power as the recording power,
In the third step, a value obtained by adding a margin by multiplying an average value of the first set value and the second set value by a certain ratio is determined as an optimum peak power,
When determining the bias power as the recording power,
In the process of obtaining the lower limit value and the upper limit value of the bias power, the first to third steps are executed,
In a third step in the process of obtaining the lower limit value, an average value of the first set value and the second set value is determined as the lower limit value of the bias power,
In a third step in the process of obtaining the upper limit value, an average value of the first set value and the second set value is determined as the upper limit value of the bias power,
A recording power determination method for an optical disc apparatus, wherein a value obtained by internally dividing the lower limit value and the upper limit value into a predetermined ratio is determined as an optimum bias power.   2. The recording power determination method for an optical disc apparatus according to claim 1, wherein an error rate or jitter of the reproduction signal is detected as the reproduction signal quality.   2. The recording power determination method for an optical disk device according to claim 1, wherein a detection result of a sector whose reproduction quality satisfies a predetermined defect condition is excluded from the detection result used for determining the recording power.   2. The recording power determination method for an optical disc apparatus according to claim 1, wherein when recording the predetermined data, data different from the previously recorded data is recorded in each sector.   2. The recording power determination method for an optical disc apparatus according to claim 1, wherein when recording the predetermined data, the predetermined data is recorded in each sector after the data recorded in each sector is once erased. An optical disc apparatus having a plurality of tracks connected in a spiral shape, each track recording data on an optical disc composed of a plurality of sectors,
Setting means for executing a first step of setting a plurality of recording power values which are laser output powers during data recording;
Executes a second step of recording predetermined data in a plurality of sectors in a predetermined area with recording power of each set value, reproducing data from each sector after data recording, and detecting the quality of a reproduction signal for each sector Recording / detecting means to perform,
Among the recording power setting values when a predetermined number or more of sectors satisfying a predetermined condition for the reproduction signal quality are obtained, the recording power setting value for when a predetermined number or more of the sectors satisfying the predetermined condition for the reproduction signal quality cannot be obtained A first setting value that is the recording power setting value closest to
Of the recording power setting values when a predetermined number or more of sectors satisfying a predetermined condition for reproduction signal quality cannot be obtained, the setting values for recording power when a predetermined number or more of sectors satisfying a predetermined condition for reproduction signal quality are obtained a second set value which is the set value of the nearest recording power,
And determining means for executing a third step of determining the recording power based on the first and second set values,
The determining means includes
When determining the peak power as the recording power,
In the third step, a value obtained by adding a margin by multiplying an average value of the first set value and the second set value by a certain ratio is determined as an optimum peak power,
When determining the bias power as the recording power,
In the process of obtaining the lower limit value and the upper limit value of the bias power, the first to third steps are executed,
In a third step in the process of obtaining the lower limit value, an average value of the first set value and the second set value is determined as the lower limit value of the bias power,
In a third step in the process of obtaining the upper limit value, an average value of the first set value and the second set value is determined as the upper limit value of the bias power,
An optical disc apparatus characterized in that a value obtained by internally dividing the lower limit value and the upper limit value into a predetermined ratio is determined as an optimum bias power.   7. The optical disc apparatus according to claim 6, wherein the recording / detecting unit detects an error rate or jitter of the reproduction signal as the reproduction signal quality.   7. The optical disc apparatus according to claim 6, wherein the determination means excludes a detection result of a sector whose reproduction quality satisfies a predetermined defect condition from a detection result used for determining the recording power.   7. The optical disc apparatus according to claim 6, wherein the recording / detecting means records data different from the previously recorded data in each sector when recording the predetermined data.   7. The optical disc according to claim 6, wherein when recording the predetermined data, the recording / detecting means records the predetermined data in each sector after once erasing the data recorded in each sector. apparatus.

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