JP3807062B2 - Recording method, phase shift detection circuit, and information apparatus using them - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording method on an information recording medium, a phase shift detection circuit for making the quality of a recorded signal constant, and an information apparatus using them, and particularly to an information apparatus compatible with high-density information recording.
[0002]
[Prior art]
A recordable optical disc has a feature capable of recording a large amount of information and being compatible with a medium. Information is reproduced by condensing laser light on the information recording surface and detecting reflected light modulated by the recording mark. Information recording is performed by thermally forming a recording mark by irradiating the information recording surface with a beam having a power higher than that of the reproduction light.
[0003]
There are three types of recordable optical disc media: (1) magneto-optical type, (2) phase change type, and (3) drilling type, and the magneto-optical type is a write-once application that can record only once. For example, a drilling type using an organic dye typified by CD-R is widely used. In order to increase the recording density of a recording optical disk, it is necessary to precisely form a smaller mark, so that precise control of recording power is required.
[0004]
However, in an actual optical disk apparatus, a predetermined temperature distribution is obtained on the information recording surface even if the output of the light source is kept constant due to the influence of dynamic fluctuations such as ambient temperature, laser wavelength, and light spot distortion. It ’s difficult.
[0005]
For this reason, as described in, for example, Japanese Patent Laid-Open No. 6-195713, a technique called “trial writing” for obtaining an optimum value of recording power in a test area before recording user data is conventionally known as a magneto-optical disk, Used for CD-R.
[0006]
In the conventional test writing method, as shown in FIG. 2, the dense pattern and the sparse pattern are alternately recorded, and the difference between the average levels of the dense pattern and the sparse pattern, that is, the asymmetry ΔV is detected from the reproduction signal, and it is substantially zero. Is obtained as the optimum recording condition. When the recording power P is smaller than Po, the recording mark is smaller than the predetermined shape, so ΔV is a negative value. When the recording power P is larger than Po, the recording mark is larger than the predetermined shape, and ΔV is a positive value. It becomes. Therefore, the optimum recording power Po can be obtained by detecting the asymmetry ΔV while changing the recording power within an appropriate range. In this method, a linear response can be obtained when the recording mark width is constant even if the recording mark length changes.
[0007]
[Problems to be solved by the invention]
Problems that occur when the conventional asymmetry detection test writing method is applied to a phase change optical disk will be described below. Since the phase change optical disk can reproduce information using the difference in reflectance between crystal and amorphous, it can use the same reproduction system as an apparatus such as a CD-ROM and is excellent in compatibility with a ROM type optical disk. There are features. The recording mark is formed as an amorphous mark obtained by melting the recording film with a laser beam at one end and then rapidly cooling it. The recording mark is erased by crystallizing the amorphous mark by maintaining the temperature at a temperature higher than the crystallization temperature and lower than the melting point. On the other hand, even if one end melts during recording, there is a phenomenon called `` recrystallization '' that returns to the crystal again if the cooling rate is slow, and the shape of the recording mark is determined not only by the distribution of the reached temperature but also by cooling conditions. There is a feature that. This is the main mechanism difference between the phase change optical disk and other recording media such as a magneto-optical disk.
[0008]
Here, a GeSbTe phase change material was used as a recording film as an example of a phase change optical disk, and the characteristics of a conventional asymmetry type test writing were measured. As a configuration of the disk sample, a plastic substrate having a diameter of 120 mm and a thickness of 0.6 mm is used as a substrate, and a ZnS-SiO2 first optical interference film, a GeSbTe phase change recording film, and a ZnS-SiO2 second optical interference film are formed thereon. A film in which an Al—Ti reflective film and a UV protective film are sequentially laminated is used. A track groove for land / groove recording having a track pitch of about 0.7 μm was formed on the substrate. A recording waveform having three recording levels Pw, Pe, and Pb as shown in FIG. 3 is used, and n-1 Tw / 2 is used to form a recording mark having a channel bit length nTw with a channel clock Tw. A width pulse was irradiated. As a data modulation method, an 8-16 modulation method in which 1 Tw is formed as a mark having a length of about 0.2 μm on the disk was used. The shortest mark length is 3 Tw, and the longest mark length is 14 Tw. The light spot used for recording is a light beam condensed by an objective lens having a numerical aperture of 0.6 using a semiconductor laser having a wavelength of 680 nm as a light source. The linear velocity was measured under the condition of 6 m / s. The center value Po of the power margin when the random signal was overwritten on this disk was the recording power Pw = 10.5 mW and the erasing power Pe = 3.8 mW. The recording power at the time of trial writing was changed while maintaining a constant ratio of Pw: Pe = 10.5 (mW): 3.8 (mW). The bottom power Pb was constant at 0.5 mW. Here, 3Tw as a dense pattern and 8Tw as a sparse pattern and a repeated pattern of spaces are selected.
[0009]
FIG. 4 shows the relationship between the recording power and the asymmetry amount ΔV. The vertical axis in the figure is obtained by normalizing the asymmetry amount ΔV with the signal amplitude of the sparse pattern. The amount of asymmetry ΔV was increased to the right when the recording power was in the range of 9 to 14 mW, but it was found that it changed only about 3% on the minus side compared to 15% on the plus side. . In addition, there was a tendency for the slope to become gentler when the recording power was lower than Po, and a phenomenon that the sign was reversed near the recording start point was also observed. Furthermore, at the optimum recording power Po, the asymmetry amount ΔV that should be zero does not become zero.
[0010]
These characteristics on the low power side are the effect of recrystallization during recording as described above. Compared to the sparse pattern, the dense pattern has a shorter laser irradiation time, so the heat accumulation is smaller and the conditions are more rapid heating / cooling, and the dense pattern has a smaller amount of recrystallization. This becomes prominent near the recording threshold value, and as a result, the dense pattern has a larger mark width than the sparse pattern.
[0011]
Optimum power when the conventional asymmetry detection test writing method is applied to a phase change optical disk because the amount of shake differs between the plus and minus sides and the asymmetry amount is not uniquely determined with respect to the recording power. Finding Po requires complex processing.
[0012]
Next, the characteristics of the rewrite life of the phase change optical disk will be described. Even with a phase change optical disk, deterioration progresses as rewriting is repeated. The main points are (1) recording film flow and (2) reflectance change. The flow of the recording film is considered to occur due to thermal stress in a state where the recording film is melted during recording. The change in reflectivity is related to the flow of the recording film, but is considered to be caused by a deviation in the composition of the recording film or the penetration of the interference film material due to thermal stress.
[0013]
As an example, the deterioration characteristics of the phase change optical disk used in the experiment are shown in FIG. FIG. 5 (a) shows the relationship between the recording mark length and the flow size. Here, continuous overwriting was performed 80,000 times with the recording power Po. Each pattern is a repetitive pattern having the same mark and space, and recording was performed by dividing the block into 200-byte blocks with an interval of 50 bytes. For the flow, the length of the region where the initial signal amplitude decreased to ½ or less was measured at the start and end of each block. The vertical axis of the table in FIG. 5A is the length of the flow region with respect to the start end. As can be seen in FIG. 5A, the shorter the mark length, the longer the flow region, and the 3Tw mark has a length twice or more that of the 11Tw mark. When the flow occurs, a decrease in signal amplitude, an increase in jitter, a decrease in the amount of reflected light, and the like occur.
[0014]
FIG. 5B shows the average reflected light amount level of the 3Tw pattern and the 8Tw pattern normalized with an initial value of 100%. As the number of rewrites increases, the average amount of reflected light decreases, but the decrease is not the same between 3Tw and 8Tw. This indicates that the deterioration speed of the recording film depends on the mark length.
[0015]
That is, it can be seen from FIG. 5 that the asymmetry amount, which is the difference in the average reflected light amount level, changes depending on the number of rewrites. Therefore, the correct recording power cannot be set if there is a difference in the number of rewrites between the test area where trial writing is performed and the area where user data is actually recorded.
[0016]
As described above, the trial writing by the conventional asymmetry detection is not suitable for the phase change optical disk from the two viewpoints of (1) linearity and uniqueness of target point detection and (2) mark length dependence of recording film deterioration. I understood it.
[0017]
An object of the present invention is to solve the above problems, provide a test writing method suitable for a phase change optical disk, and provide an information device using the same.
[0018]
[Means for Solving the Problems]
In the present invention, the following means are used to achieve the first object.
(1) Since recording of a sparse pattern and a dense pattern causes a difference in deterioration due to the mark length, trial writing is performed by controlling the recording power so as to record a trial writing pattern of a random mark pattern, preferably a single mark repeated pattern. I do.
(2) The phase shift between the data edge and the clock edge is detected while changing the recording power, and the jitter is equivalently measured to obtain the optimum recording condition. At this time, the optimum recording condition is directly obtained, or the recording threshold value at which the jitter is equal to or less than the threshold value is obtained, and the optimum recording condition is obtained by multiplying it by a constant.
[0019]
The effectiveness of trial writing by such a method will be described below. FIG. 6 shows the relationship between the recording power and the jitter between the data edge and the clock edge. Here, jitter was measured when 11 Tw marks / spaces were repeatedly recorded and when the same random mark pattern was overwritten (overwritten) 10 times. In general, the ECC code correction capability used for optical disks has a limit of 1/1000 to 1/10000 of the bit error rate of the reproduction data, and therefore, the jitter is about 15% is the upper limit at which no error occurs. Therefore, as shown in FIG. 6, the center of the range of the recording power margin where the jitter of the reproduction signal after overwriting the random mark pattern is 15% or less is the target recording condition for the trial writing.
[0020]
Here, five samples of samples having different recording film compositions and film configurations were prepared so that trial writing could be applied to various optical discs, and the same measurement was performed. . The horizontal axis of FIG. 7A is the ratio η between the threshold value for starting recording by DC light and the threshold power for pulse recording. A large value means that the recording film is exposed to the DC light and the recording film is partially It shows the degree to which the crystalline state is restored by recrystallization even when melted, that is, the degree of ease of recrystallization of each disk. The vertical axis represents the slope m of the curve in FIG. 6 at a jitter of 15%. As is clear from FIG. 7 (a), when a random mark pattern is recorded (random signal), the value of m changes depending on the value of η, whereas an 11Tw repeated mark is recorded. In the case of (11 Tw repetitive signal), the value of m is large and constant. When obtaining the threshold power Pth for recording, the larger the value of m, the higher the detection accuracy, and the smaller the change due to the medium, the better. Therefore, the 11Tw repetitive signal is more suitable than the random signal. The difference between the two is that the jitter of the repetitive signal of a single pattern is mainly the fluctuation of the data edge, while the jitter of the random signal includes a shift component depending on the mark length in addition to the edge fluctuation component. This is thought to be because of this.
[0021]
FIG. 7 (b) summarizes the relationship between the ratio α and η value of the optimum power and the recording threshold power. From the figure, it was found that the ratio α was distributed in the range of 1.15 to 1.30 for five sample disks having different characteristics, and averaged about 1.25. Even when other disks having different characteristics are considered, the ratio α is considered to be in the range of 1.1 to 1.4.
[0022]
From the above examination results, among the above-described trial writing methods, the optimum power can be obtained with the highest accuracy by recording a single pattern and determining the recording threshold power Pth and multiplying by the ratio α. I understood. At this time, if the power is gradually scanned from the low power side, the detection point is uniquely determined, so that trial writing suitable for the phase change optical disk can be realized.
[0023]
Note that this method can be applied not only to a phase change optical disk but also to a magneto-optical disk and a punch-type write-once optical disk.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Example 1 Trial writing method
FIG. 1 shows the configuration of the phase shift detection means of the present invention and the results of a test writing experiment using the same. In FIG. 1A, a clock extracted from a reproduction signal by using a PLL (Phase Locked Loop) circuit and an edge pulse (data edge pulse) when a test writing mark is reproduced are input to a phase comparator. A pulse having a length corresponding to the phase shift is generated. This pulse is pulse width-voltage converted into a phase error voltage by an integrator and passes through a level comparator, so that the data edge pulse is transferred to the error edge counter as an error pulse only when the phase error voltage is larger than the threshold value. And counted. At the same time, the all edge counter counts all data edges, and when the specified value is reached, the operation of the error edge counter is stopped. The value of the error edge counter is captured by the CPU and processed. With such a configuration, the amount of jitter can be taken into the CPU as the ratio of the total number of edges counted by the total edge counter to the phase difference with the PLL clock that is larger than the threshold value.
[0025]
The advantage of this method is that the fluctuation of the phase error voltage due to the effects of uneven recording sensitivity and servo error fluctuations in the sector to be reproduced can be smoothed by integrating the number of pulses, and measurement stability is improved. It is to increase. Further, there is an advantage that the circuit scale can be made smaller than that in which the phase error voltage is directly taken in using an AD converter or the like. Thus, by quantifying the phase shift between the PLL clock and the data edge, it becomes possible to measure a physical quantity equivalent to the jitter obtained from a measuring instrument such as a jitter analyzer in the optical disc apparatus.
[0026]
FIG. 1B shows experimental results when test writing is performed using the phase shift detection method of the present invention. The medium used was the same sample as that shown in FIG. The gain of the integrator was determined so that a phase error voltage of 1.8 V was obtained when the window width Tw ± 50% was shifted. This corresponds to a phase shift sensitivity of 0.01 V / deg. The threshold value of the level comparator was 0.8 V (± 22% of the window width), and the set value of the edge counter was 2560. In the test writing pattern, the repetition signal recording power condition of 11 Tw was constant at Pw: Pe = 11 mW: 4.5 mW. As shown in the figure, the change of the error count number with respect to the recording power was the same as the jitter characteristic of FIG. The threshold value corresponding to a jitter of 15% corresponds to an error count of 700. At this time, the threshold power Pth = 8.8 mW was obtained, and α = 1.25 times was obtained, thereby obtaining the recording condition Po = 11 mW. The error was 2% or less with respect to the value of 10.8 mW obtained by actual measurement in FIG.
[0027]
FIG. 8 shows a circuit configuration of a phase shift detector actually used for measurement. In the figure, SCLK is a PLL clock, RDGT is a reproduction gate corresponding to the data area of the sector, PCA is a data edge pulse, PCB is a pulse obtained by extracting only a pulse to be compared with the data edge from the PLL clock, and RESET is an integrator reset signal. , S / H is a control signal for sampling and holding the phase error voltage, UP is a pulse having a length corresponding to the phase advance amount when the data edge is advanced compared to the PLL clock, and DOWN is data Each of the pulses represents a pulse having a length corresponding to the phase delay amount when the phase is delayed compared to the PLL clock.
[0028]
In order to explain the operation of this circuit, it will be explained with reference to the timing chart of FIG. A pulse PCA signal and a PCB signal for comparing phases are generated from a PLL clock and a data binary signal (DLDATA). The generation block of the PCA signal and the PCB signal uses another gate array not shown in FIG. 8, but the logic itself is simple and can be generated by a known means. Two pulse UP signals and a DOWN signal are generated from the PCA signal and the PCB signal using a D-flip-flop and a NAND gate. A phase shift pulse can be obtained by the logical sum of the UP signal and the DOWN signal, that is, the exclusive logical sum of the PCA signal and the PCB signal. This is integrated for a period of 1.5 Tw by an integrator, reset by a RESET signal, and used as an integrator output signal. At 0.5 Tw from the start of integration, sample hold is performed by S / H to obtain a level comparator input (Comparator input) signal, which is then compared with the phase shift threshold (Slice level) by the level comparator. (Error pulse) signal can be obtained. In the present invention, two counters of error pulse and data edge are necessary. However, since it has a simple configuration and is well known, description thereof is omitted here.
[0029]
Here, as a method of detecting phase shift, a method of pulsing and counting data edges having a large phase shift is shown, but the phase shift voltage obtained by integrating the phase shift pulse described above is directly detected to detect phase shift. The amount can also be determined. In this case, since the integral value fluctuates with time, it may be detected by an AD converter or the like after further suppressing the temporal fluctuation by adding a low-pass filter or the like.
[0030]
Next, the relationship between the number of error edge counts, the threshold value of the level comparator, and jitter will be described. FIG. 10 shows the relationship between the count number of error edges and the threshold value of the level comparator. Since the integrator sensitivity is set to 0.01 V / deg as described above, the phase shift ± Tw / 2 corresponds to the threshold voltage V1 = 1.8V. Here, the case where the jitter is 25% (equivalent to the maximum value) and 8% (equivalent to the minimum value) was examined. Since the number of error edges is the count number of data edges having a phase shift equal to or greater than the phase shift threshold voltage, the error edge count decreases as the phase shift threshold voltage is increased. When the jitter between the reproduction signal and the clock is 25% and 8%, the condition that the difference in the number of error edges becomes the maximum is the threshold voltage V1 = 0.8V. The recording threshold jitter of about 15% is between the two. At this time, the change in the number of error edges with respect to the change in jitter is maximized, and the sensitivity of trial writing for finding the recording threshold can be maximized.
[0031]
FIG. 11 schematically shows the relationship between the jitter distribution, the number of error edges, and the threshold voltage. As shown in the figure, the portion where there is a phase shift greater than the threshold voltage of the phase shift with respect to the jitter distribution, that is, the edge of the hatched portion in the figure becomes an error edge and is counted.
[0032]
FIG. 12 shows the result of measuring the relationship between jitter and the number of error edges. It can be seen that the number of error edges increases linearly as the jitter increases. Therefore, it was confirmed that the jitter can be measured equivalently by detecting the number of error edges. The reason why the number of error edges does not become zero when the jitter is zero depends on the offset of the phase shift detection circuit and the response speed. When the phase shift decreases, the circuit element does not operate, and UP and DOWN pulses The main reason is that it does not occur. The characteristics vary depending on the discrete IC circuit configuration used in the experiment. However, since a detection range of 7% to 25% is confirmed with respect to a jitter value of 15% to be detected, there is no practical problem in trial writing. Consideration regarding the detection range and linearity is indispensable also when such a circuit is made into an LSI. Similarly, it is necessary to consider the threshold voltage of the phase shift and the number of error edges as a detection target so that the detection sensitivity does not decrease. In this way, the relationship between power and error count as shown in FIG. 1B can be obtained. In this method, since the error count changes greatly with respect to the change in recording power near the recording threshold, even when the threshold voltage V1 fluctuates effectively due to temperature change or power supply voltage change, the recording power is determined. The error can be reduced.
[0033]
FIG. 13 is a flowchart showing a test writing sequence (procedure) according to the present invention. Hereinafter, this procedure will be described.
[0034]
In the trial writing process, first, a predetermined track is accessed as preparation for trial writing, and recording power and the like are set. At this time, it is preferable to perform test writing in a plurality of areas such as a predetermined area on the inner circumference side and a predetermined area on the outer circumference side in consideration of the influence of the deflection of the disk.
[0035]
Next, a track check is performed by trying to play the track to be written on trial. At this time, if there is a steep level change due to dust, scratches, flow, etc. from the playback signal, it is determined that a defect has been detected, and the same track check process is repeated after moving to another track, and there is no defect. Go to the track.
[0036]
Next, it is determined whether or not data is recorded in the reproduction signal of the track on which trial writing is performed. When there is a signal, an erasing operation using DC light is performed so that no signal is recorded on the track. As a specific defect and signal detection method, there is a method that utilizes the fact that the data signal mainly includes high frequency components of 1 MHz or higher, and the defect mainly includes low frequency components of 100 kHz or lower. If the difference between the upper envelope and the lower envelope obtained by performing envelope detection on each of the playback signals after filtering the band of the reproduced signal, signal distortion due to data amplitude and defects can be detected.
[0037]
Next, the power is changed for each sector of the trial writing track, and a trial writing mark (here, 11 Tw repeated mark or random mark pattern) is recorded on the disk. At this time, since it is generally difficult to switch the recording power condition instantaneously, recording may be performed every other sector, and power setting may be performed in the sector between recording.
[0038]
In the information device, if the 11Tw repeat mark is recorded, control is performed so as to record the 11Tw repeat mark. However, in the trial writing according to the present invention, recording is performed while gradually changing the recording power, so that the information is recorded on the disc. It goes without saying that the test writing mark does not always have the same mark length (mark length corresponding to 11 Tw). At this time, the test writing mark is recorded so that the recording power is initially low and gradually increased. This is because if trial writing is performed from a large power at the beginning, the trial writing may be performed at a power larger than the optimum recording power, which may damage the disc. The recording power is changed so that the ratio of Pw and Pe is constant, and scanning is performed. This is because sensitivity variations among discs, spot distortion due to aberrations, and the like can be converted into power. In order to correct such fluctuations by trial writing, power scanning with a constant ratio is suitable. However, only the recording power Pw or only the erasing power Pe may be changed. It is appropriate to gradually change the power change rate in the range of 2% -5% in consideration of the detection sensitivity and the processing time.
[0039]
Next, the recorded test writing mark is reproduced to read the number of error edges. In the all edge counter, all data edges are counted, and when the specified value is reached, the operation of the error edge counter is stopped, and the number of error edges contained therein is read. Since the total number of data edges is determined by the disk format or the like, it may be stored in the information device. At this time, as described above, the test writing mark is recorded while gradually changing the recording power, and the mark length recorded on the disc may fluctuate due to the influence of the recording power. When the written mark is reproduced, the PLL clock signal and the mark edge are naturally out of phase, and this is detected as an error edge pulse.
[0040]
Here, in order to reduce the influence of dust and defects in the sector, one sector is divided into four areas, error edges are counted for each area, and the maximum and minimum values are obtained from the four results obtained. The average count of the remaining two points is calculated. As a result, even if dust or a defect exists in the sector, it can be excluded from the detection result if the size is 1/4 or less of the sector. Further, in order to reduce the influence of the unevenness of the recording sensitivity of the medium in the circumferential direction, a weighted average of three consecutive measured values is taken at a ratio of 1: 2: 1 of the number of error edges in the sector.
[0041]
Recording and reproduction are repeated until the number of error edges thus obtained satisfies the recording threshold condition, and the recording threshold power Pth is obtained.
[0042]
Further, the optimum recording power Po is obtained by multiplying by a constant α (= about 1.25). This Po is used as the recording power Pw. However, since the recording power Pw and the erasing power Pe are in a fixed ratio, it goes without saying that if Pw is obtained, Pe is also uniquely obtained.
[0043]
The optical disc apparatus stores the optimum recording conditions obtained in this way, and when actually recording data, the data is recorded according to the optimum recording conditions.
[0044]
Although trial writing was performed when the disc was replaced, when data was recorded after the trial writing was completed, it was also found that there was an abnormality in recording power due to so-called RAW (Read After Write) etc. You should do it. Here, the case where the mark length of the repetitive pattern is 11 Tw has been described. Although it is not particularly limited to 11 Tw, if the mark length is too short, the above-described flow may increase, or the adjacent mark may be thermally affected when the mark is recorded. The mark length is preferred.
[0045]
FIG. 14 shows the relationship between the recording power and the number of error edges when trial writing is actually performed according to the sequence of FIG. The format of the optical disk used is a sector size of 2 kbytes. A specially developed LSI was used to generate and detect error pulses. Since the sector is divided into four areas for processing, the total number of edges of the signal in each area is 864 (360h). An error edge counter built in the LSI is an 8-bit counter. In this configuration, the phase error detection threshold is set so that the number of error edges corresponding to a jitter of 15% is 128 (80 h). The number of error edges shown in FIG. 14 is a value obtained by recording data every other sector in accordance with the above sequence and performing an intra-sector 4-division averaging process and an inter-sector averaging process during reproduction. From FIG. 14, the recording threshold power (Pth) was 10 mW, and the optimum recording power (Po) was 12.5 mW. Needless to say, the values of the threshold power and the optimum power coincide with the results of measurement using a separate jitter analyzer. As a result of continuous execution of this method 10,000 times, the recording power detection result was 12.5 mW ± 3%, which was found to be sufficiently accurate.
[0046]
FIG. 15 shows a sequence of another embodiment of the present invention. Here, a method for directly obtaining the recording power that minimizes the jitter by actually overwriting, instead of obtaining the recording threshold power will be described.
[0047]
In this sequence, after confirming that there is no recording data in the sector, overwriting is performed every other sector while changing the power. At this time, in order to obtain the optimum power more accurately, the recording is continuously performed at least twice with the same power in the same sector. A condition for minimizing the number of error pulses at this time is obtained and used as a recording condition. Since this method requires overwriting with a power larger than the optimum condition, the flow deterioration of the medium is accelerated, but there is an advantage that the minimum jitter power at the time of direct overwriting can be obtained. The signal to be recorded may be a repetitive signal having a specific mark length or a data pattern (random signal) used for the format and certification of the medium. The basic sequence of the playback system is the same by simply changing the setting of all edge counters according to the difference in the average mark length of the signal to be recorded.
[0048]
FIG. 16 shows the relationship between the recording power and the error count when trial writing is performed according to the sequence of FIG. An optimum power of 12.5 mW can be obtained as a condition for minimizing the error count.
[0049]
<< Example 2 >> Information device
An example of an information device in which the trial writing method and the phase shift detection method of the first embodiment are mounted will be described with reference to FIG. The optical disk medium 8 is rotated by a motor 162. The light intensity control means 171 controls the light generation means 131 to generate light 122 so that the light intensity commanded by the central control means 151 is generated, and this light 122 is condensed by the light collection means 132 and the light spot 7 is reflected. It is formed on the optical disk medium 8. Using the reflected light 123 from the light spot 7, the light detection means 133 detects it. This light detection means is composed of a light detector divided into a plurality of parts. The reproduction means 191 reproduces information recorded on the optical disk medium using the reproduction signal 130 from the photodetector.
[0050]
The reproducing means 191 incorporates the test writing signal detecting means shown in the first embodiment. Further, as shown in the first embodiment at the time of trial writing, the function of recording the trial writing pattern while changing the recording power, the function of taking in the trial writing signal detected by the trial writing signal detecting means, and processing the fetching result are optimal. The central control means 151 has the function of determining power.
[0051]
By using the information apparatus of the present invention, it is possible to obtain an optimum recording power by correcting fluctuations in media and light spots having different sensitivities, so that recording and reproduction of high-density information can be stably performed.
[0052]
Here, an embodiment has been described in which the recording power is optimized by obtaining a condition on the low power side where the jitter is equal to or less than the threshold value and multiplying it by a constant. In the same configuration, (1) to obtain the condition that the error count is minimum (jitter is minimum), (2) to obtain the condition on the low power side and the condition on the high power side where the jitter is below the threshold, It is also easy to determine the power condition that is an approximate average value of them.
[0053]
The gist of the present invention is to optimize the recording conditions by detecting the quality of the reproduced signal as a phase shift amount, and not only the phase change optical disc but also the magneto-optical disc, the punch-type write-once optical disc, and the magnetic Applicable to discs and the like. In the case of magnetic disks and some magneto-optical disks, the control amount of the recording conditions corresponding to the laser power described above is the strength of the magnetic field applied to the medium, so the amount of phase shift while changing the strength of the magnetic field May be detected.
[0054]
【The invention's effect】
According to the present invention, optimum recording conditions for recording data can be obtained reliably, and stable high-density recording becomes possible. In particular, since trial writing suitable for the characteristics of the phase change optical disk can be performed, the optimum recording condition can be reliably obtained even for the phase change optical disk for which the conventional recording method cannot obtain the optimum recording condition. High density recording can be performed.
[Brief description of the drawings]
FIG. 1 shows a configuration of a phase shift detection method of the present invention and a test writing test result using the same.
FIG. 2 is a schematic diagram of a conventional test writing method for detecting the amount of asymmetry.
FIG. 3 is a diagram showing a recording waveform.
FIG. 4 is a diagram showing characteristics when a conventional asymmetry method is applied to a phase change disk;
FIG. 5 is a diagram showing changes in flow and reflectivity due to rewriting of a phase change optical disk.
FIG. 6 shows the relationship between recording power, data edge, and clock edge jitter.
FIG. 7 is a diagram illustrating the relationship between the sensitivity of trial writing and the ratio α in each disk.
FIG. 8 shows an example of a circuit configuration of a phase shift detector according to the present invention.
FIG. 9 is a timing chart showing the circuit operation of the phase shift detector of the present invention.
FIG. 10 is a diagram showing the relationship between the number of error edges and the threshold value of the level comparator.
FIG. 11 is a diagram schematically showing a relationship among a jitter distribution, the number of error edges, and a threshold voltage.
FIG. 12 is a diagram showing the relationship between jitter and the number of error edges.
FIG. 13 shows an example of a trial writing sequence according to the present invention.
FIG. 14 is a diagram showing the relationship between recording power and the number of error edges in the present invention.
FIG. 15 shows another embodiment of the trial writing sequence according to the present invention.
FIG. 16 is a diagram showing the relationship between recording power and the number of error edges in the present invention.
FIG. 17 is a diagram showing a configuration of an information device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 7 ... Light spot, 8 ... Optical disk medium, 131 ... Light generation means, 132 ... Condensing means, 133 ... Light detection means, 151 ... Central control means, 191 ... Reproduction means.

Claims (9)

A method for recording on an optical information recording medium,
A process of recording mark rows while changing recording conditions on the optical information recording medium,
A process of reproducing the mark string to obtain a reproduction signal;
Generating a clock signal from the reproduced signal;
Detecting a mark row edge recorded from the reproduction signal;
Detecting a phase difference between the edge and the clock signal;
A process of determining recording conditions according to the spread of the phase difference distribution;
A recording method comprising recording information according to the recording conditions. A method for recording on an optical information recording medium,
A process of recording a mark row while changing a recording power condition on the optical information recording medium,
A process of reproducing the mark string to obtain a reproduction signal;
Generating a clock signal from the reproduced signal;
Detecting a mark row edge recorded from the reproduction signal;
Detecting a phase difference between the edge and the clock signal;
Extracting an edge whose phase difference is larger or smaller than a predetermined value;
Counting the number of extracted edges for each recording condition;
A process of determining a recording power condition according to the counted number of edges,
A recording method comprising recording information according to the recording power condition. The recording method according to claim 2,
The extracted edge is an edge whose phase difference of the clock signal is larger than a predetermined value, and a recording power at which the number of extracted edges is minimized is defined as a recording power. Means for generating a clock signal from a reproduction signal reproduced and inputted from an optical information recording medium in which information is recorded in a mark row;
Means for detecting an edge of a mark row recorded from the reproduction signal;
Means for detecting a phase difference between the edge and the clock signal;
Means for extracting an edge whose phase difference is larger or smaller than a predetermined value;
Means for counting the number of extracted edges for each recording condition;
A phase shift detection circuit comprising: An information device for recording and reproducing information on a disc-shaped optical information recording medium,
Means for rotating the optical information recording medium;
Means for condensing a beam of a semiconductor laser on the optical information recording medium;
Laser driving means for modulating the output of the semiconductor laser in accordance with data to be recorded;
The phase shift detection circuit according to claim 4,
And a CPU for controlling the operation of each means and circuit,
According to the recording method according to claim 1, data is recorded on the optical information recording medium, and a reproduction signal is input to the phase shift detection circuit to detect a phase shift amount,
An information device for determining the laser output. Each time the information recording medium is mounted, the mark is recorded on the information recording medium while changing the recording power of the light applied to the information recording medium, and the light recording power corresponding to the information recording medium is obtained. An information device comprising:
Means for reproducing the mark string to obtain a reproduction signal;
Means for generating a clock signal from the reproduced signal;
Means for detecting an edge of a mark row recorded from the reproduction signal;
Means for detecting a phase difference between the edge and the clock signal;
Means for determining recording conditions in accordance with the spread of the phase difference distribution,
An information device for recording information according to the recording condition. Each time the information recording medium is mounted, the recording condition for recording the data on the information recording medium is obtained by recording a mark on the information recording medium while changing the recording power of the light applied to the information recording medium. An information device comprising:
Means for reproducing the mark string to obtain a reproduction signal;
Means for generating a clock signal from the reproduced signal;
Means for detecting an edge of a mark row recorded from the reproduction signal;
Means for detecting a phase difference between the edge and the clock signal;
Means for extracting an edge whose phase difference is larger or smaller than a predetermined value;
Means for counting the number of extracted edges for each recording condition;
Means for determining a recording power condition in accordance with the counted number of edges,
An information apparatus for recording information according to the recording power condition. A method for recording on an optical information recording medium,
A process of recording a mark row consisting of repetition of marks and spaces of the same length while changing the recording power condition on the optical information recording medium,
A process of reproducing the mark string to obtain a reproduction signal;
Generating a clock signal from the reproduced signal;
Detecting a mark row edge recorded from the reproduction signal;
Detecting a phase difference between the edge and the clock signal;
A process of obtaining a recording threshold power at which a spread of the phase difference distribution is smaller than a predetermined value; a process of determining a recording power condition by multiplying the recording threshold power by a constant;
A recording method comprising recording information according to the recording conditions. The recording method according to claim 8, wherein
The recording threshold power is approximately 15% jitter value, which is the standard deviation of the spread of the phase difference distribution,
A recording method characterized in that a constant multiplied by the recording threshold power is in a range of approximately 1.1 to 1.4.

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