JPH10320777A - Recording method, phase deviation detecting circuit and information device using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preform a trial write suitable for a phase transition optical disk by detecting phase deviations between data edges and clock edges while changing recording powers and calculating an optimum recording condition while measuring jitter equivalently. SOLUTION: When edge pulses of the clock and the trial write mark extracted from a reproduced signal by using a PLL circuit are inputted to a phase comparator and pulses having lengths equivalent to phase deviations between them are subjected to a pulse width - voltage conversion to be converted into a phase error voltage by an integrator and the phase error voltage is larger than a threshold value, error edges are transferred to a counter to be counted. Moreover, when all data edges are counted and the count value reaches a specified value, the operation of an edge counter is stopped and the count value is fetched to a CPU to be processed. Thus, the phase error voltage is smoothed by integrating a value equivalent to the fluctuation of the phase error voltage due to the influence of variations of recording sensitivities and the fluctuation of servo errors being in sectors to be reproduced as the number of pulses and the stability of the measurement is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording information on an information recording medium, a phase shift detecting circuit for keeping the quality of a recorded signal constant, and an information apparatus using the same. The present invention relates to an information device corresponding to.

[0002]

2. Description of the Related Art A recordable optical disk has a feature that a large amount of information can be recorded and the medium can be interchanged. Reproduction of information is performed by focusing a laser beam on an information recording surface and detecting reflected light modulated by a recording mark. Recording of information is performed by irradiating a beam having a larger power than the reproduction light to the information recording surface to thermally form a recording mark.

[0003] As a recordable optical disk medium,
There are three types: (1) magneto-optical type, (2) phase change type, and (3) drilling type. The magneto-optical type is used for rewriting, and the CD-R is used for the write-once use that can record once. Drilling types using organic dyes have become widespread. In order to increase the recording density of a recordable optical disk, it is necessary to precisely form smaller marks, so that precise control of the recording power is required.

However, in an actual optical disk apparatus, even if the output of the light source is kept constant due to the influence of dynamic fluctuations such as ambient temperature, laser wavelength, light spot distortion, etc., the information recording surface has a predetermined temperature. It is difficult to obtain a distribution.

For this reason, for example, Japanese Patent Application Laid-Open No. Hei 6-195713
As described in Japanese Patent Application Laid-Open Publication No. H10-209, a technique called "test writing" for obtaining an optimum value of a recording power in a test area before user data is recorded has been conventionally used for a magneto-optical disk and a CD-R.

In the conventional test writing method, a dense pattern and a sparse pattern are alternately recorded as shown in FIG. 2, and the difference between the average level of the dense pattern and the sparse pattern, that is, the asymmetry ΔV is detected from the reproduced signal. The recording power Po which becomes 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 that 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. Becomes Therefore, the optimum recording power Po can be obtained by changing the recording power within an appropriate range and detecting the asymmetry ΔV. With this method, a linear response can be obtained when the recording mark width is constant even if the recording mark length changes.

[0007]

A problem that occurs when the conventional test writing method for asymmetry detection is applied to a phase-change optical disk will be described below. Since a phase change optical disk can reproduce information by using a difference in reflectance between a crystal and an amorphous phase, it can use the same reproduction system as a device such as a CD-ROM, and has excellent 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 once with a laser beam and then quenching it. Further, the erasing of the recording mark is performed by maintaining the temperature at the crystallization temperature or higher and the melting point or lower to crystallize the amorphous mark. On the other hand, there is a phenomenon called "recrystallization" that returns to the crystal if the cooling rate is low even if it melts once during recording, and the shape of the recording mark is determined not only by the distribution of the ultimate temperature, but also by taking into account the cooling conditions There is a characteristic that. This is the main difference between the phase change optical disk and other recording media such as a magneto-optical disk.

Here, G is an example of a phase change optical disk.
Using an eSbTe-based phase change material for the recording film, the characteristics of the conventional asymmetry-type test writing were measured. The configuration of the disk sample was such that the substrate had a diameter of 120 mm and a thickness of 0.1 mm.
Using a 6mm plastic substrate, ZnS-S
iO2 first optical interference film, GeSbTe phase change recording film, Z
nS-SiO2 second light interference film, Al-Ti reflection film, UV
The protective film was sequentially laminated. Track grooves for land / groove recording having a track pitch of about 0.7 μm were formed on the substrate. A recording waveform having three recording levels Pw, Pe, and Pb as shown in FIG. 3 is used. Assuming that a channel clock is Tw and n-1 Tw / 2 are used to form a recording mark having a channel bit length nTw. A width pulse was applied. 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 a disk was used. The shortest mark length is 3 Tw,
The longest mark length is 14 Tw. The light spot used for recording is obtained by condensing an object lens having a numerical aperture of 0.6 using a semiconductor laser having a wavelength of 680 nm as a light source. Linear velocity is 6
The measurement was performed under the condition of m / s. The center value Po of the power margin when a random signal is overwritten on this disk is the recording power Pw = 10.5 mW and the erasing power Pe
= 3.8 mW. The recording power for trial writing is P
w: Pe was changed at a ratio of 10.5 (mW): 3.8 (mW) while keeping the ratio constant. Bottom power Pb is 0.5m
W was constant. Here, a 3 Tw mark and space repetition pattern of 3 Tw was selected as a dense pattern and an 8 Tw mark as a sparse pattern.

FIG. 4 shows the relationship between the recording power and the asymmetry amount ΔV. The vertical axis in the figure represents the asymmetry amount ΔV normalized by the signal amplitude of the sparse pattern. The asymmetry amount ΔV showed a right-up characteristic when the recording power was in the range of 9 to 14 mW. However, it was found that the asymmetry amount ΔV changed only about 3% on the minus side compared to 15% on the plus side. . In addition, when the recording power was lower than Po, the inclination tended to be gentle, and the sign was reversed near the recording start point. Furthermore, at the optimum recording power Po, the asymmetry amount ΔV that should become 0 does not become 0.

[0010] Such characteristics on the low power side are the effects of the recrystallization during recording described above. Compared to the sparse pattern, the dense pattern has less heat build-up due to the shorter laser irradiation time, and is under more rapid heating / cooling conditions.The dense pattern has a smaller amount of recrystallization, and the difference is Since it becomes remarkable near the recording threshold value, as a result, the dense pattern has the effect of increasing the mark width as compared with the sparse pattern.

When the amount of asymmetry is different between the plus side and the minus side and the amount of asymmetry is not uniquely determined with respect to the recording power, the conventional test writing method for asymmetry detection is applied to a phase change optical disk. In order to find the optimum power Po, complicated processing is required.

Next, the characteristics of the rewritable life of the phase change optical disk will be described. Even with a phase-change optical disk, the deterioration progresses as rewriting is repeated. The main factors are (1) flow of the recording film and (2) change in reflectance. It is considered that the flow of the recording film occurs 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 the deviation of the composition of the recording film or the penetration of the interference film material due to thermal stress.

As an example, FIG. 5 shows the deterioration characteristics of the phase change optical disk used in the experiment. FIG. 5A shows the relationship between the recording mark length and the magnitude of the flow. Here, the recording power was set to Po, and overwriting was continuously performed 80,000 times. Each pattern is a repetitive pattern in which the mark and the space are equal, and each pattern has 200 bytes at intervals of 50 bytes.
Recording was performed by dividing the block into byte units. For the flow, the length of the region where the initial signal amplitude was reduced to １ ／ or less was measured at the beginning and end of each block. The vertical axis of the table in FIG. 5A is the length of the flow region from the start end. As can be seen from FIG. 5A, the shorter the mark length, the longer the length of the flow region, and the length of the 3 Tw mark is more than twice as long as the 11 Tw mark. When the flow occurs, a decrease in signal amplitude, an increase in jitter, a decrease in reflected light level, and the like occur.

FIG. 5B shows a 3 Tw pattern and an 8 Tw pattern.
The average reflected light amount level of the pattern is normalized by setting the initial value to 100%. The average reflected light amount level decreases as the number of times of rewriting increases, but the manner of the decrease does not match between 3 Tw and 8 Tw. This indicates that the speed of deterioration of the recording film depends on the mark length.

That is, FIG. 5 shows that the asymmetry amount, which is the difference between the average reflected light amount levels, changes according to the number of times of rewriting. Therefore, if there is a difference in the number of rewrites between the test area where the test writing is performed and the area where the user data is actually recorded, the correct recording power cannot be set.

As described above, the conventional test writing based on asymmetry detection can be performed by (1) linearity and uniqueness of target point detection,
(2) Dependence of the deterioration of the recording film on the mark length was found to be unsuitable for a phase change optical disc from two viewpoints.

An object of the present invention is to solve the above problems, to provide a test writing method suitable for a phase change optical disk, and to provide an information device using the same.

[0018]

According to the present invention, the following means are used in order to achieve the first object. (1) When a sparse pattern and a dense pattern are recorded, there is a difference in deterioration depending on the mark length.
Preferably, the test writing is performed by controlling the recording power so as to record a test writing pattern of a repeated pattern of a single mark. (2) The phase shift between the data edge and the clock edge is detected while changing the recording power, and jitter is equivalently measured to determine the optimum recording condition. At this time, the optimum recording condition is obtained directly, or a 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.

The effectiveness of test 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, the jitter was measured when the mark / space of 11 Tw was repeatedly recorded and when the same random mark pattern was overwritten (overwritten) ten times. Generally, the correction capability of an ECC code used for an optical disk is such that the bit error rate of reproduced data is 1/100.
Approximately 15% jitter due to the limit of 0 to 1/10000
Is the upper limit at which no error occurs. Therefore, as shown in FIG. 6, the target recording condition for test writing is the center of the range of the recording power margin where the jitter of the reproduced signal after overwriting the random mark pattern is 15% or less.

In this case, five samples of samples having different recording film compositions and film configurations were prepared and subjected to the same measurement so that test writing could be applied to various optical disks. Summarized in The horizontal axis in FIG. 7A is the ratio η between the threshold value of the start of recording by DC light and the threshold power of pulse recording, and a large value means that the recording film is irradiated with the DC light and the recording film has one end. This indicates the degree to which the disk returns to the crystalline state by recrystallization even after melting, that is, the degree to which each disk is easily recrystallized. The vertical axis represents the slope m of the curve in FIG. 6 at a jitter of 15%. FIG.
(a) As is clear, in the case where the random mark pattern is recorded (random signal), the value of m changes depending on the value of η, but the 11 Tw repeated mark is recorded. In the case (11 Tw repetitive signal), the value of m is large and constant. When the recording threshold power Pth is obtained, the detection accuracy is higher as the value of m is larger and the change due to the medium is smaller, so that the 11 Tw repetitive signal is more suitable than the random signal. The difference between the two is that the jitter of a single-pattern repetitive signal is mainly caused by 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 fluctuation of the edge. It is thought that it is.

FIG. 7B summarizes the relationship between the ratio α between the optimum power and the recording threshold power and the η value. From the figure, it was found that the ratio α was distributed in a range of 1.15 to 1.30 with respect to five sample disks having different characteristics, and was about 1.25 on average. It should be noted that the ratio α is 1.1 to 1.1 even when other disks having different characteristics are considered.
It is considered to be in the range of 1.4.

From the above examination results, among the above-described test writing methods, a single pattern is recorded, the threshold power Pth of the recording is obtained, and the ratio α is multiplied to obtain the optimum power with the highest accuracy. I knew it could be done. At this time, if the power is gradually scanned from the low power side, the detection point is uniquely determined, so that test writing suitable for a phase change optical disk can be realized.

The present method is applicable not only to a phase-change optical disk but also to a magneto-optical disk and a perforated write-once optical disk.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 Test Writing Method FIG. 1 shows a configuration of a phase shift detecting means of the present invention and an experimental result of test writing using the same. In FIG. 1A, a clock extracted from a reproduction signal using a PLL (Phase Locked Loop) circuit and an edge pulse (data edge pulse) when reproducing a test writing mark are input to a phase comparator. The pulse having the length corresponding to the phase shift is generated. This pulse is pulse-width-to-voltage converted to a phase error voltage by an integrator and passed 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 greater than a threshold value. It is counted. At the same time, the all edge counter counts all data edges, and stops the operation of the error edge counter when the count reaches a specified value. The value of the error edge counter is taken into the CPU and processed. With such a configuration, the amount of jitter can be taken into the CPU as a percentage of the total number of edges counted by the all-edge counter that has a phase difference with the PLL clock larger than the threshold value.

The advantage of this method is that the fluctuation of the phase error voltage due to the influence of the fluctuation of the recording sensitivity or the fluctuation of the servo error in the sector to be reproduced can be smoothed by integrating it as the number of pulses. The stability is increased. Also, there is an advantage that the circuit scale can be reduced as compared with directly taking in the phase error voltage using an AD converter or the like. In this way, 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 device such as a jitter analyzer in the optical disk device.

FIG. 1B shows an experimental result when test writing is performed using the phase shift detection method of the present invention. As the medium, the same sample as that shown in FIG. 6 was used. The gain of the integrator was determined such that a 1.8 V phase error voltage was obtained when the window width Tw ± 50% 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. Trial writing pattern is 1
The repetition signal recording power condition of 1 Tw is Pw: Pe = 1.
1 mW: constant at 4.5 mW. As shown in the figure, the change in the error count number with respect to the recording power was the same as the jitter characteristic shown in FIG. The threshold value corresponding to the jitter of 15% was equivalent to the error count number of 700.
At this time, threshold power Pth = 8.8 mW is obtained, and α
= 1.25 times the recording condition Po = 11 mW
was gotten. This is a value of 10.8 m obtained by the actual measurement in FIG.
For W, the error was 2% or less.

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, RESET is a reset signal of the integrator, S / H is a control signal for sampling and holding the phase error voltage, and UP
Is a pulse having a length corresponding to the amount of phase advance when the data edge is advanced in phase compared to the PLL clock;
DOWN represents a pulse having a length corresponding to the amount of phase delay when the data edge is behind the phase of the PLL clock.

The operation of this circuit will be described 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). PC
Although another gate array (not shown in FIG. 8) is used as a block for generating the A signal and the PCB signal, the logic itself is simple and can be generated by well-known means. D-flip-flop and NAND from PCA signal and PCB signal
A gate is used to generate two pulse UP and DOWN signals. The logical sum of the UP signal and the DOWN signal, that is, P
A phase shift pulse can be obtained by the exclusive OR of the CA signal and the PCB signal. This is 1.5 Tw with an integrator
, And reset by the RESET signal to obtain an integrator output signal. At 0.5 Tw from the start of integration, sample / hold is performed by S / H to obtain an input signal of a level comparator (Comparator input), and a threshold value of a phase shift (Slice level) is obtained by the level comparator.
By comparing with, an error pulse signal can be obtained. In the present invention, two other counters, ie, an error pulse and a data edge, are required. However, since the counter has a simple configuration and is well known, the description is omitted here.

Here, as a method of detecting a phase shift, a method is described in which a data edge having a large phase shift is pulsed and counted, but the phase shift voltage obtained by integrating the above-described phase shift pulse is directly detected. The phase shift amount can also be obtained by using At this time, since the integrated value fluctuates with time, a low-pass filter or the like may be further added to suppress the temporal fluctuation, and then the signal may be detected by an AD converter or the like.

Next, the relationship between the number of error edge counts, the threshold value of the level comparator, and the jitter will be described. FIG.
0 indicates the relationship between the count number of the error edge and the threshold value of the level comparator. As described above, the sensitivity of the integrator is 0.
Since the phase shift is set to 01V / deg, the phase shift ± Tw / 2 corresponds to the threshold voltage V1 = 1.8V. Here, the case where the jitter was 25% (corresponding to the maximum value) and 8% (corresponding to the minimum value) was examined. The number of error edges is the number of counts of data edges having a phase shift greater than or equal to the threshold voltage of the phase shift. Therefore, the greater the threshold voltage of the phase shift, the smaller the number of error edges. Playback signal and clock jitter are 2
In the case of 5% and 8%, the condition under which the difference between the number of error edges was the maximum was the threshold voltage V1 = 0.8V. Approximately 15% of the recording threshold jitter is between the two. At this time, the change in the number of error edges with respect to the change in jitter becomes maximum, and the sensitivity of test writing for finding the recording threshold can be maximized.

FIG. 11 schematically shows the relationship between the jitter distribution, the number of error edges, and the threshold voltage. As shown in the figure, a portion having a phase shift equal to or more than the threshold voltage of the phase shift with respect to the jitter distribution, that is, an edge of a hatched portion in the figure becomes an error edge and is counted.

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 equivalently measured 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 and the response speed of the phase shift detection circuit. When the phase shift becomes small, the circuit element stops operating, and the UP and DOWN pulses are generated. The main cause is thought to be no longer occurring. The characteristics vary depending on the discrete IC circuit configuration used in the experiment. However, since the detection range was confirmed from 7% to 25% with respect to the jitter value to be detected of 15%, there is no practical problem in performing test writing. Even when such a circuit is formed into an LSI, it is essential to consider the detection range and the linearity. Similarly, it is necessary to consider the threshold voltage of the phase shift and the number of error edges to be detected so as not to lower the detection sensitivity. In this way, the relationship between the power and the error count as shown in FIG. 1B is obtained. In this method, the change in the error count number with respect to the change in the recording power near the recording threshold is large. Therefore, even if the threshold voltage V1 fluctuates effectively due to a temperature change or a power supply voltage change, the recording power is determined. Can be reduced.

FIG. 13 shows a test writing sequence according to the present invention.
(Procedure) is shown as a flowchart. Hereinafter, this procedure will be described.

In the test writing process, first, a predetermined track is accessed and recording power and the like are set in preparation for the test writing. At this time, test writing may be performed in a plurality of areas such as a predetermined area on the inner peripheral side and a predetermined area on the outer peripheral side of the disk in consideration of the influence of the bending of the disk.

Next, a track check is performed by trying to reproduce a track to be trial-written. At this time, if there is a steep level change due to dust, scratches, flow, etc. from the reproduced signal, it is determined that a defect has been detected, the track is moved to another track, and the same track check processing is repeated, so that there is no defect. Go to truck.

Next, it is determined whether or not data is recorded in the reproduction signal of the track to be trial-written. If there is a signal, an erasing operation using DC light is performed, and a signal is not recorded on the track. As a specific method for detecting a defect and a signal, there is a method utilizing a fact that a data signal mainly includes a high frequency component of 1 MHz or more and a defect mainly includes a low frequency component of 100 kHz or less. After the reproduction signal is filtered and band-separated, the difference between the upper envelope and the lower envelope obtained by performing envelope detection on each of them can be used to detect signal distortion due to data amplitude and defects.

Next, a test write mark (here, 11 Tw repeat mark or random mark pattern) is recorded on the disk by changing the power for each sector of the test write track. At this time, it is generally difficult to switch the recording power conditions instantaneously, so that recording may be performed every other sector, and the power may be set in the sector between recordings.

In the information apparatus, if an 11 Tw repetition mark is recorded, control is performed so as to record the 11 Tw repetition mark. However, in the test writing of the present invention, recording is performed while gradually changing the recording power. The test writing marks to be recorded must have the same mark length (11 Tw
It is needless to say that the mark length is not necessarily equal to the mark length. At this time, the test writing mark is recorded by setting the recording power to a small power at first and gradually increasing the recording power. This is because, if the test writing is performed first with a large power, the test writing may be performed with a power larger than the optimum recording power, and the disc may be damaged. Further, the scanning is performed while changing the recording power so that the ratio between Pw and Pe becomes constant. This is because variations in sensitivity for each disk, spot distortion due to aberration, and the like can be converted into power. To correct such fluctuations by test writing, power scanning with a fixed ratio is suitable, but only the recording power Pw or only the erasing power Pe may be changed. It is appropriate to gradually change the power in the range of 2% to 5% in consideration of the detection sensitivity and the processing time.

Next, the recorded test writing mark is reproduced to read the number of error edges. The all edge counter counts all data edges, stops the error edge counter when it reaches a specified value, and reads the number of error edges contained therein. Since the total number of data edges is determined by the disk format or the like, it is sufficient to store this 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 vary under the influence of the recording power. When the written mark is reproduced, the phase of the PLL clock signal and the phase of the mark edge are naturally shifted, and this is detected as an error edge pulse.

Here, in order to reduce the influence of the presence of dust or defects in the sector, one sector is divided into four areas, error edges are counted for each area, and the maximum value is determined from the four results obtained. The average count number of the remaining two points excluding the minimum value is obtained. As a result, even if dust or a defect is present in a sector, if the size is not more than 1/4 of the sector, it can be excluded from the detection result. Also,
In order to reduce the influence of unevenness in the circumferential direction on the recording sensitivity of the medium, a weighted average of three consecutive measurement values is calculated at a ratio of 1: 2: 1 of the number of error edges of the sector.

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.

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 have a fixed ratio, it goes without saying that if Pw is determined, Pe is uniquely determined.

The optimum recording conditions obtained in this way are stored in the optical disk device, and when actually recording data, data recording is performed according to the optimum recording conditions.

Note that the test writing was performed when the disk was replaced. However, when data was recorded after the test writing was completed, it was found that the recording power was abnormal due to so-called RAW (Read After Write) or the like. It is good to do it sometimes. Here, the case where the mark length of the repetitive pattern is 11 Tw has been described. Especially 11T
Although the mark length is not limited to w, if the mark length is too short, the flow as described above may increase, or the mark may have a thermal effect on an adjacent mark when the mark is recorded. Preferably, the length is longer.

FIG. 14 shows the relationship between the recording power and the number of error edges when test writing is actually performed in accordance with the sequence of FIG. The format of the used optical disk has a sector size of 2 kByte. An LSI specially developed was used for generating and detecting the error pulse.
In order to process the sector by dividing it into four regions, the total number of edges of the signal in each region was set to 864 (360h). The error edge counter built into the LSI is 8 bi.
t is a counter. In this configuration, the phase error detection threshold is set so that the number of error edges corresponding to 15% of jitter is 128 (80h). 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. FIG.
4, 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 coincided with the results measured using a separate jitter analyzer. As a result of continuously executing this method and 10,000 times, the detection result of the recording power was 12.5 mW ± 3%, and it was found that there was sufficient accuracy.

FIG. 15 shows the sequence of another embodiment of the present invention. Here, a method will be described in which, instead of obtaining the recording threshold power, the overwriting is actually performed to directly obtain the recording power that minimizes the jitter.

In this sequence, after confirming that there is no recording data in a sector, overwriting is performed every other sector while changing the power. At this time, in order to more accurately obtain the optimum power, recording is continuously performed in the same sector at least twice with the same power. At this time, a condition for minimizing the number of error pulses is obtained, and this is used as a recording condition. In this method, overwriting with a power larger than the optimum condition is required, so that the flow deterioration of the medium is accelerated. However, there is an advantage that the minimum jitter power at the time of overwriting is directly obtained. The signal to be recorded may be a repetitive signal of a specific mark length or a data pattern (random signal) used for the format and certification of the medium. The setting of the reproduction system is the same as that of the basic sequence except that the setting of all the edge counters is changed according to the difference in the average mark length of the signal to be recorded.

FIG. 16 shows the relationship between the recording power and the error count when test writing is performed in accordance with the sequence of FIG. An optimum power of 12.5 mW can be obtained as a condition for minimizing the error count.

Second Embodiment Information Device An example of an information device in which the test writing method and the phase shift detecting 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 so that the light intensity is instructed by the central control means 151 so that the light 12
The light 122 is condensed by the condensing means 132 to form a light spot 7 on the optical disk medium 8. Using the reflected light 123 from the light spot 7, the light is detected by the light detecting means 133. This light detecting means is composed of a plurality of divided photodetectors. Reproduction means 191
Reproduces information recorded on the optical disk medium using the reproduction signal 130 from the photodetector.

The reproducing means 191 incorporates the test writing signal detecting means shown in the first embodiment. Further, a function of recording a test write pattern while changing the recording power at the time of test writing as described in the first embodiment, a function of capturing a test write signal detected by the test write signal detection unit, and processing the capture result to optimize the function. The central control means 151 has the function of determining the power.

By using the information apparatus of the present invention, it is possible to obtain the optimum recording power by correcting the fluctuation of the medium and the light spot having different sensitivities, so that it is possible to stably record and reproduce high-density information. .

Here, an embodiment has been described in which the condition on the low power side where the jitter is equal to or less than the threshold value is obtained, and the recording power is optimized by multiplying it by a constant. With the same device configuration, (1) the condition that the error count is minimum (jitter is minimum) is also obtained, It is also easy to find a power condition that results in a substantially average value thereof.

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. Not only a phase change optical disk but also a magneto-optical disk or a hole-type write-once optical disk, Further, the present invention can be applied to a magnetic disk or the like. In the case of a magnetic disk or some magneto-optical disks, the amount of control of the recording conditions corresponding to the laser power described above is the intensity of the magnetic field applied to the medium, so the amount of phase shift while changing the intensity of the magnetic field is changed. Should be detected.

[0054]

According to the present invention, optimal recording conditions for recording data can be reliably obtained, and stable high-density recording can be performed. In particular, since test writing suitable for the characteristics of a phase change optical disc can be performed, the optimum recording conditions can be reliably obtained even for a phase change optical disc for which the optimum recording conditions could not be obtained by the conventional test writing method, and stable. High-density recording can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a phase shift detection method according to the present invention and experimental results of trial writing using the configuration.

FIG. 2 is a schematic diagram of a conventional test writing method for detecting an asymmetry amount.

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 a change in flow and reflectivity due to rewriting of a phase change optical disc.

FIG. 6 shows a relationship between recording power, data edge, and clock edge jitter.

FIG. 7 is a diagram showing the relationship between the sensitivity of test writing and the ratio α in each disc.

FIG. 8 is an embodiment showing a circuit configuration of a phase shift detector according to the present invention.

FIG. 9 is a timing chart showing a circuit operation of the phase shift detector of the present invention.

FIG. 10 is a diagram illustrating a relationship between the number of error edges and a threshold value of a level comparator.

FIG. 11 is a diagram schematically illustrating a relationship between a jitter distribution, the number of error edges, and a threshold voltage.

FIG. 12 is a diagram showing a relationship between jitter and the number of error edges.

FIG. 13 shows an embodiment of a test 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 test writing sequence of 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]

7 light spot, 8 optical disk medium, 131 light generating means, 132 light collecting means, 133 light detecting means, 151
... Central control means, 191 ... Reproduction means.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kuki Sugiyama 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Visual Information Media Division of Hitachi, Ltd. (72) Inventor Tetsuya Fushimi 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (72) Inventor: Toshimitsu Kaku 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture

Claims (11)

[Claims] A step of recording a mark on an information recording medium; a step of reading a mark recorded on the information recording medium to obtain a reproduction signal; a step of detecting a phase shift amount between the reproduction signal and a reference signal; Recording a data in accordance with the recording condition via a step of determining a condition for recording data on the information medium according to an amount. 2. The recording method according to claim 1, wherein the information recording medium is a disc-shaped optical information recording medium, and wherein the reference signal is a clock signal generated from a reproduction signal. By changing the power of the laser beam irradiated on the information recording medium and recording specific data, and detecting the amount of phase shift according to the power from the reproduction signal, the power corresponding to the threshold power for recording can be calculated. A recording method characterized in that the recording power is optimized by finding and multiplying the value by a constant. 3. The recording method according to claim 1, wherein the information recording medium is a disk-shaped optical information recording medium, and the reference signal is a clock signal generated from a reproduction signal. The specific power is recorded by changing the power of the laser beam irradiated on the information recording medium, and the phase shift amount corresponding to the power is detected from the reproduced signal, so that the recording power is minimized so that the phase shift amount is minimized. A recording method characterized by optimizing the data. Means for generating a reference clock signal from an input reproduction signal; means for generating a phase shift voltage corresponding to a phase shift amount between the reproduction signal and the reference clock; a predetermined threshold voltage and the phase; Means for modulating and outputting the reproduced signal or the reference clock in accordance with the magnitude relationship of the shift voltages. 5. An information apparatus for recording / reproducing information on / from a disk-shaped optical information recording medium, comprising: means for rotating the optical information recording medium; and a beam of a semiconductor laser focused on the optical information recording medium. 5. A light emitting means, a laser driving means for modulating an output of the semiconductor laser according to data to be recorded, a phase shift detecting circuit according to claim 4, and a CPU for controlling the operation of each means and the circuit. According to the recording method described in any one of Items 1 to 3, data is recorded on the optical information recording medium, the reproduced signal is input to the phase shift detection circuit, the phase shift amount is detected, and the laser output is determined. An information device characterized by the following. 6. An information apparatus, wherein a mark is recorded on the information recording medium every time the information recording medium is mounted, and a recording power of light corresponding to the information recording medium is obtained. An information apparatus, wherein a mark having the same channel bit length is controlled to be repeatedly recorded on a recording medium, and a recording power of light on the information recording medium is obtained. 7. A mark is recorded on the information recording medium while changing the recording power of light applied to the information recording medium every time the information recording medium is mounted, and a light recording power corresponding to the information recording medium is obtained. An information device configured as described above, wherein a mark is recorded with a recording power lower than a recording power of a light to be obtained, and a light recording power for the information recording medium is obtained. 8. A mark is recorded on the information recording medium while changing the recording power of light applied to the information recording medium every time the information recording medium is mounted, and a recording power of light corresponding to the information recording medium is obtained. An information device configured as described above, wherein recording of light on the information recording medium is performed by detecting a phase shift between a signal indicating an end of the mark and a clock signal obtained by reproducing the mark. An information device characterized by obtaining power. 9. An information apparatus, wherein each time an information recording medium is mounted, a mark is recorded on the information recording medium and a recording condition for recording data on the information recording medium is obtained. An information apparatus, wherein the recording condition is obtained by controlling to repeatedly record marks having the same channel bit length on a recording medium. 10. A recording condition for recording a mark on the information recording medium and recording data on the information recording medium while changing a recording power of light applied to the information recording medium every time the information recording medium is mounted. An information device configured as described above, wherein a mark is recorded with a recording power lower than a recording power of light to be obtained, and the recording condition is obtained. 11. A recording condition for recording a mark on the information recording medium and recording data on the information recording medium while changing a recording power of light applied to the information recording medium every time the information recording medium is mounted. An information device configured as described above, wherein the recording condition is obtained by detecting a phase shift between a signal indicating an end portion of the mark and a clock signal obtained by reproducing the mark. Information device.