JP2003257028A - Method and device for recording optical information and optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for recording optical information capable of easily deciding an optimal recording compensation value to prevent thermal interferences even when information recording is carried out at a very high density. <P>SOLUTION: A multipulse string constituted of the repetition of a mark and space which has a time length equivalent to one of combinations of mark lengths to be recorded and previous space lengths is trial-written on an optical information recording medium, optimal recording pulse conditions are decided for the combination from its reproducing signal and, for the other combination of the mark lengths to be recorded and the previous space lengths, recording pulse conditions are uniquely decided by utilizing the fact that heat diffusion by recording is decided only by the horizontal heat conductivity of a recording film. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an optical information recording medium such as a rewritable phase change type optical disk and records information on the optical information recording medium, an optical information recording apparatus and an optical information recording medium. Regarding

[0002]

2. Description of the Related Art At present, in a rewritable phase change type optical disk such as a DVD-RAM or a DVD-RW, a laser is focused according to a groove for track servo provided on an optical disk substrate, a so-called group, and the focused laser is used. Information is recorded by controlling the temperature of the condensing part and causing a reversible change between a crystalline state and an amorphous state. Normal,
Although the recording film of the optical disk is in a crystalline state (high reflectance), it is raised to a high temperature by a laser in recording information to form an amorphous (low reflectance) mark.
In the case of overwriting, the amorphous mark is changed to a crystalline state and the recorded information is erased.

When forming an amorphous mark, there is thermal interference between the mark to be recorded and the mark previously recorded. Therefore, laser emission is performed to compensate for the interference and recording compensation is performed. ing. To perform this recording compensation, the optical disc recording apparatus has a table in which the mark length to be recorded and the compensation amount for each of the previous space lengths are written. To determine the optimum recording compensation value suitable for the optical disc.

Known recording compensation of this type is as follows:
Japanese Unexamined Patent Application Publication No. 2000-200418 discloses a method and a device for determining a recording pulse condition of an optical disc, and describes a recording pulse for each combination of a mark length to be recorded and a previous space length from a writable optical disc. It is possible to reduce the jitter by reading out the recording pulse standard condition that specifies the position, performing trial writing under this recording pulse standard condition, and changing the recording pulse standard condition uniformly or individually to find the optimum recording pulse condition. Have been described.

Further, Japanese Patent Laid-Open No. 2000-149262, “Information recording method and information recording apparatus”, discloses that the first power level of the energy beam is in the first state, and the first power level is higher than the first power level. Second at a power level of 2
In order to set to the state of, the pulse train timing adjustment,
It is described that the energy adjustment mechanism is used.

[0006]

However, even in the techniques described in these patent publications, trial writing is performed under standard recording pulse conditions for each combination of the mark length to be recorded and the previous space length, and the recording pulse is recorded. It is not easy to change the standard condition to determine the optimum recording compensation value because there are many combinations of the mark length to be recorded and the previous space length. Further, it is impossible to correct the table in which the compensation amount is written in the optical disc under the recording pulse condition which is largely deviated from the standard condition of the recording pulse.

An object of the present invention is to provide an optical information recording method capable of easily determining an optimum recording compensation value for preventing thermal interference even when information recording is highly densified. An object is to provide an optical information recording device and an optical information recording medium.

[0008]

In order to achieve the above object, the present inventors have examined the characteristics of a thin film material constituting a rewritable, large-capacity, high-speed optical information recording medium.
As a result, since the heat diffusion in the horizontal direction of the recording medium is determined only by the recording film and has little relationship with other sandwiched layers, (1,7) RLL (Run
When the Length Limited) code is used, when the mark length to be recorded is set in the horizontal direction and the previous space length is set in the vertical direction, the mark length to be recorded is equal to the previous space length. The present invention has been made in view that if the time width of the leading pulse on the diagonal line to the right is determined, the time width of the leading pulse corresponding to other portions can be easily determined thereafter.

That is, according to the optical information recording method of the present invention, the write pulse standard condition for specifying the position of the write pulse is not recorded in advance for each combination of the mark length to be recorded and the previous space length. A method for determining an optimum recording pulse condition even from an optical information recording medium, wherein a mark having a time length corresponding to one of a combination of the mark length to be recorded and a previous space length is used. A multi-pulse train consisting of repetitions is trial-written on the optical information recording medium, the optimum recording pulse condition for the combination is determined from the reproduction signal, and the other mark length and the previous space length are combined. On the other hand, the fact that the diffusion of heat by recording is determined only by the thermal conductivity in the horizontal direction of the recording film is used to determine the recording pulse condition in a significant way. It is characterized in that the.

Further, in the optical information recording method of the present invention, when the mark length to be recorded is in the horizontal direction and the previous space length is in the vertical direction, and the time width of the head pulse of the multi-pulse train is tabulated, the recording is performed. The time width of the first pulse on the right-downward diagonal line is previously determined using the heat conduction characteristics of the recording film so that the mark length and the previous space length are equal, and the portion other than the right-downward diagonal line is determined. The time width of the head pulse corresponding to is determined by using the time width of the head pulse on the diagonal line to the right that is determined previously.

Further, in the optical information recording method of the present invention, the time width of the first pulse corresponding to the portion above the diagonal line to the right is utilized by utilizing the thermal interference characteristic of the recording film. It is characterized in that the determination is made by using the time width of each of the leading pulses immediately below.

Further, in the optical information recording method of the present invention, the time width of the leading pulse corresponding to a portion below the right-downward diagonal line is adjacent to the right of the portion by utilizing the thermal interference characteristic of the recording film. It is characterized in that the determination is made using the time width of each of the leading pulses immediately above.

Further, in the optical information recording method of the present invention, the time width of the leading pulse corresponding to a portion above or below the diagonal line to the right is determined by utilizing the thermal interference characteristics of the recording film. It is characterized in that it is decided symmetrically above.

Further, in the optical information recording method of the present invention, the time width of the leading pulse on the diagonal line to the right is defined as (1,7)
When recording using the RLL code, the mark length to be recorded and the previous space length are both 4T (T is a clock period)
It is characterized in that the time width of the leading pulse at which the carrier-to-noise ratio at that time becomes maximum is set.

Further, the optical information recording apparatus of the present invention is optimal for recording even from a writable optical information recording medium in which the recording pulse standard condition for specifying the position of the recording pulse is not recorded in advance by the optical information recording method of the present invention. It is characterized in that the pulse condition is determined.

The optical information recording medium of the present invention is characterized in that the optimum recording pulse conditions determined by the optical information recording method of the present invention are recorded.

In the optical information recording medium of the present invention, the recording film of the optical information recording medium is Sb and Te, or Ge and Sb and T.
e is a main raw material.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments of the invention with reference to the accompanying drawings. Figure 1
FIG. 1 is a block diagram showing an embodiment of the optical information recording device of the present invention. In FIG. 1, 1 is a rewritable phase-change type optical disk, 2 is an optical head for reading recorded data from the optical disk 1 to obtain a reproduction signal, and 3 is a duty feedback slice after correcting the frequency characteristic of the reproduction signal. Equalizer binarization circuit for obtaining a digital binarized signal from an analog reproduced signal by the method, and 4
Detects the edge of the binarized signal, extracts the reproduced clock synchronized with this, converts the binarized signal into data synchronized with the reproduced clock, and
It is a PLL clock extraction circuit that outputs a time shift of edges of a binarized signal as a phase error pulse.

Reference numeral 5 denotes a phase error pulse, which is an output signal of the PLL clock extraction circuit 4, and equalizer binarization circuit 3
Jitter measurement circuit that determines the output signal of Hi or Lo, converts the average value of the pulse width into a voltage, and outputs the jitter voltage. Reference numeral 6 represents a 2T mark (T is a clock period) described later to reproduce the carrier pair. CNR to obtain noise ratio
(Carrier to Noise Ratio) measurement circuit, and 7 is CN
It is a recording compensation table preparation circuit for preparing a recording compensation table by the procedure described later based on the carrier-to-noise ratio obtained from the R measurement circuit 6 and the jitter voltage obtained from the jitter measurement circuit 5.

Reference numerals 8, 9 and 10 are pattern generating circuits for generating a recording pattern. In particular, 8 is a random pattern generating circuit for generating a random pattern (random data such as recording data), and 9 and 10 are. 2T and 4T repetitive pattern generation circuits for generating repetitive patterns of 2T and 4T marks, respectively, which will be described later. Reference numeral 11 is a (1,7) RLL conversion circuit that converts the random pattern generated by the random pattern generation circuit 8 into a (1,7) RLL code. Further, 12 is supplied with an output signal of any one of the 2T repetitive pattern generation circuit 9, the 4T repetitive pattern generation circuit 10 and the (1,7) RLL conversion circuit 10 via the changeover switch SW, and records the supplied signal. A recording compensation circuit for compensating using the recording compensation table created by the compensation table creating circuit 7 and a laser driving unit 13 for recording the output of the recording compensation circuit 12 on the optical disc 1 by the optical head 2.

In the following, in the optical information recording apparatus shown in FIG. 1, a method of creating a recording compensation table created by the recording compensation table creating circuit 7 will be described. In the following description, a recording compensation method called (N-1) type is used to compensate for thermal interference between a mark to be recorded and a previous mark, and a (1,7) RLL code is used as a recording code. To (for this reason,
(The movable piece of the changeover switch SW in FIG. 1 is tilted to the contact a side)
I shall. In the (N-1) type recording compensation system, when the thermal interference between the mark to be recorded and the previous mark becomes severe, the emission time width of the first pulse constituting the multi-pulse train is recorded with the mark length and the previous mark. It is important to change it according to the space length of.

As is well known, the (1,7) RLL code has a minimum mark of 2T and a maximum mark of 8T.
The (N-1) type recording compensation waveform in the case of recording a mark is shown. In FIG. 2, (a) is a clock and (b) is
Shows an NRZI signal, and (c) shows a multi-pulse train. The multi-pulse train shown in FIG. 2C is a signal actually written on the optical disc. Here, the emission time width of the leading pulse in the multi-pulse train is Ttop, the emission time width of the multi-pulse train excluding the leading pulse is Tmp, Let Tle be the emission time width of the last cooling pulse, and P be the emission level of the multi-pulse train laser including the first pulse.
w, the emission level of the cooling pulse laser is Pb,
Then, the emission level of the laser during the other period is set to Pe.

FIG. 3 shows recording conditions for a single frequency signal of 2T mark-2T space. Also in FIG.
Similar to FIG. 2, (a) shows a clock, (b) shows an NRZI signal, and (c) shows a multi-pulse train. First, the procedure for determining the optimum emission time width Ttop of the leading pulse and the emission time width Tle of the cooling pulse will be described with reference to FIG. Step 1. The emission time width Tle of the cooling pulse is set to 1T which can reduce thermal interference, and the emission time width Tt of the first pulse is set.
While changing op, recording and reproducing a single frequency signal (carrier) of 2T mark-2T space on the optical disc,
Carrier to Noise Ratio (CNR)
Is searched for the maximum emission time width a44. Where 2
The T-mark-2T space single frequency signal is
It is generated in the T-repeated pattern generation circuit 9, and the movable piece of the changeover switch SW is tilted to the contact point b side to record on the optical disc 1 via the recording compensation circuit 12, the laser drive unit 13, and the optical head 2. At this time, the route from the recording compensation table creating circuit 7 to the recording compensation circuit 12 is opened.

Step 2. The emission time width a44 found is
Whatever the length is, it is written in Table 1 (when the table is completed, it becomes a recording compensation table) as a value when the mark length to be recorded is equal to the previous space length. Therefore, the values of a44 are shown side by side on the diagonal line to the right (see Table 1).

[0025]

[Table 1]

Step 3. Next, the 4T mark is recorded on the optical disc. Although the waveform of the 4T mark is not shown, it can be easily associated with the waveform of the 8T mark shown in FIG. In order to record the 4T mark on the optical disk, the movable piece of the changeover switch SW of FIG. 1 is tilted to the contact c side, the 4T mark generated in the 4T repetitive pattern generating circuit 10 is supplied to the recording compensation circuit 12, and the laser driving unit is driven. 13. Recording is performed on the optical disc 1 via the optical head 2. Also at this time, the route from the recording compensation table creating circuit 7 to the recording compensation circuit 12 is left open. The emission time width Ttop of the head pulse is fixed to a44, and the emission time width Tle of the cooling pulse is fixed to 1T. After that, 2 (= 4−) is emitted at a cycle that matches the clock cycle excluding the head pulse.
2) 4T while changing the emission time width Tmp of one pulse
The mark (carrier) is recorded and reproduced, and the CNR is measured to find the emission time width that minimizes the second harmonic component of the carrier. Step 4. The light emission time width Tmp is fixed to the searched value, and the light emission time width Tle of the cooling pulse is fixed to 1T.

Step 5. The emission time width a44 of the leading pulse fixed previously is the emission time width only when the mark length to be recorded and the previous space length are both 4T (the emission time width at this time is 100 in Table 7 described later). The relational expression ax ² + bx that the inventors of the present invention measured and confirmed the other emission time widths on the diagonal line
+ C (x is the mark length to be recorded and the previous space length (here, mark length = space length), a, b, and c are coefficients which are slightly changed depending on the material system and are determined based on experiments. In this case, a = -0.5, b = 11.1, c = 63.8), the time length a44 on the diagonal other than the mark length 4T to be recorded and the previous space length 4T in Table 1 is set. Rewrite. As a result of this rewriting, the a44 arranged on the diagonal line in Table 1 has a mark length of 4T to be recorded, as shown in Table 2.
On diagonal lines other than the previous space length 4T, the value is different from a44 (see Table 2).

[0028]

[Table 2]

Step 6. Next, as shown in Table 3, the diagonally upper line is determined from the diagonal values in Table 2. The determination method is, for example, a32 = d × a22 + e × a, where a32, which is the value when the recording mark length is 3T and the previous space is 2T, is the diagonal values a22 and a33, respectively.
It derives as 33. Here, d and e are also coefficients determined based on experiments, and in this case, d = 0.7 and e = 0.3.
(See Table 3).

[0030]

[Table 3]

Step 7. By the same method, the line immediately above is decided as shown in Table 4, and by continuing this, the portion above the diagonal line determines all (see Table 4).

[0032]

[Table 4]

Step 8. For the part below the diagonal,
As shown in Table 5, the values in the upper right half determined as described above are used, and these values are copied two places below and one place to the left (see Table 5). This is determined symmetrically on the table by utilizing the thermal interference characteristics of the recording film.

[0034]

[Table 5]

Step 9. Regarding the time width a23 when the mark length to be recorded is 2T and the previous space length is 3T, as shown in Table 6, a method similar to that performed in the upper right portion, for example, a
It is derived as 23 = a24 × 0.7 + a33 × 0.3. Similarly, the time width a26 that is not determined yet, for example, when the mark length to be recorded is 2T and the previous space length is 6T, is a26 = a25 × 0.7 + a36 × 0.3.
Ask from. In this way, the entire table is determined (see Table 6).

[0036]

[Table 6]

Step 10. After all of the table is decided, looking at the increase and decrease of the jitter during direct overwrite,
Adjust the time width of the emission time width Tle of the cooling pulse so that the jitter is minimized. From the above, the emission time width Ttop of the leading pulse and the emission time width Tl of the cooling pulse
All of e and the light emission time width Tmp of the light emitted between the head pulse and the cooling pulse are determined.

In the procedure described above, when determining the emission time width Ttop of the head pulse, after determining the emission time width on the diagonal line of the recording compensation table, the emission time width of the portion above the diagonal line is determined first. In this case, however, after determining the light emission time width on the diagonal line, the light emission time width on the left side of the diagonal line may be determined first.

According to the procedure described above, when the mark length to be recorded and the previous space length are variously different, the emission time width Ttop of the first pulse is obtained from the CNR measurement result 1
One value a44 can be used to determine all points in the recording compensation table. In the (1,7) RLL code, there are 7 kinds of mark lengths to be recorded, from the minimum mark 2T to the maximum mark 8T, and the previous space length is also 7 kinds. Therefore, the number of combinations of the mark length to be recorded and the previous space length. Is 7 × 7 =
49 (equal to the number of points to be determined in the recording compensation table). Considering that all of these have been conventionally decided by trial writing, it can be seen how easy the preparation of the recording compensation table according to the present invention is.

Finally, Table 7 shows an example of the recording compensation table prepared according to the present invention.

[Table 7]

This table 7 is prepared through the following procedure. That is, first, the 2T mark-2T shown in FIG.
A single frequency signal (carrier) in the space is recorded and reproduced while changing the emission time width Ttop of the first pulse, and C
The light emission time width a44 that maximizes the NR is found (steps 1 and 2 above, Table 1). Next, while changing the emission time width Tmp of the pulse excluding the first pulse, 4T mark (carrier)
Is recorded and reproduced, CNR is measured, a light emission time width that minimizes the second harmonic component of the carrier is found, and fixed to that time width (steps 3 and 4 above). At this time, the emission time width Tle of the cooling pulse is 1T.

Next, the emission time width of the leading pulse is set to 1 only when the mark length to be recorded and the previous space length are both 4T.
00. Then, when x = 4T, the relational expression ax ² + b
Under the condition that x + c = 100, x is 2T, 3T, 5T,
Change to 6T, 7T, 8T, 84, 94, 10 respectively
6, 115, 120, 122 are determined (the above procedure 5,
Table 2).

Next, for example, in the case of a32 in the table, the line one step above the diagonal is d × 84 + e × 94 = 9.
1 (d and e are coefficients) (Procedure 6 above, Table 3).
Hereinafter, all of Table 7 are determined according to the above procedures 7 to 9.

FIG. 4 shows that, in the above procedure 1, a single frequency signal (carrier) of 2T mark-2T space is recorded and reproduced while changing the emission time width Ttop of the head pulse, and CN
The example which searched for the light emission time width which maximizes R is shown. In the case of this example, C when the emission time width Ttop of the first pulse is 1T
NR is maximum. That is, a44 = 1T.

FIG. 5 shows the result of correction made by the recording compensation table prepared according to the present invention. In FIG. 5, each hatched width is the mark length, and if the mark length is exceeded, the recorded code will not be reproduced correctly. Jitter represents this distribution as a deviation, and in the case of this example, the measurement result of the jitter distribution showed a good value of 9.8%.

Finally, the present invention includes not only the optical information recording method and the optical information recording apparatus but also the optical information recording medium in which the optimum recording pulse condition determined by the above-mentioned method or apparatus is recorded. .

[0047]

According to the present invention, it becomes easy to create a recording compensation table necessary for writing information on a phase change type optical information recording medium.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical information recording device of the present invention.

FIG. 2 shows a (N-1) type recording compensation waveform when an 8T mark is recorded.

FIG. 3 shows a recording condition of a single frequency signal of 2T mark-2T space.

FIG. 4 is 2 while changing the emission time width of the first pulse.
An example is shown in which a single frequency signal of T mark-2T space is recorded and reproduced to find a light emission time width that maximizes CNR.

FIG. 5 shows measurement results of jitter distribution.

[Explanation of symbols]

1 optical disc 2 optical head 3 Equalizer binarization circuit 4 PLL clock extraction circuit 5 Jitter measurement circuit 6 CNR measurement circuit 7 Recording compensation table creation circuit 8 Random pattern generator 9 2T repetitive pattern generation circuit 10 4T repetitive pattern generation circuit 11 (1,7) RLL conversion circuit 12 Recording compensation circuit 13 Laser drive SW selector switch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Haruki Tokumaru             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute F term (reference) 2H111 EA03 EA04 EA23 EA31 FB05                       FB09 FB12                 5D029 JA01                 5D090 AA01 BB05 CC02 EE01 EE05                       HH01 JJ12 KK04 KK05                 5D119 AA23 AA26 BA01 BB04 DA02                       HA17 HA19 HA25 HA28 HA45                       HA47 HA52 HA60                 5D789 AA23 AA26 BA01 BB04 DA02                       HA17 HA19 HA25 HA28 HA45                       HA47 HA52 HA60

Claims (9)

[Claims] 1. For each combination of a mark length to be recorded and a preceding space length, a recording pulse standard condition for specifying a recording pulse position is optimum even from a writable optical information recording medium. A method for making it possible to determine a recording pulse condition, wherein a multi-pulse train consisting of repetition of marks and spaces having a time length corresponding to one of the combination of the mark length to be recorded and the previous space length is used as the light beam. The test recording is performed on the information recording medium, the optimum recording pulse condition for the combination is determined from the reproduction signal, and the heat of recording is changed for other combinations of the mark length to be recorded and the previous space length. An optical information recording method characterized in that the diffusion pulse is determined only by the thermal conductivity in the horizontal direction of the recording film, so that the recording pulse condition is determined implicitly. Law. 2. The optical information recording method according to claim 1, wherein the mark length to be recorded is set in the horizontal direction and the preceding space length is set in the vertical direction, and the time width of the first pulse of the multi-pulse train is tabulated. The time width of the leading pulse on the right-downward diagonal line is previously determined by utilizing the heat conduction characteristics of the recording film so that the mark length to be recorded and the previous space length are equal, and the right-downward diagonal line is determined. The optical information recording method is characterized in that the time width of the head pulse corresponding to a portion other than is determined using the time width of the head pulse on the right-downward diagonal line determined previously. 3. The optical information recording method according to claim 2, wherein the time width of the first pulse corresponding to a portion above the diagonal line to the right is determined by utilizing the thermal interference characteristic of the recording film. An optical information recording method, characterized in that the time width of each of the leading pulses on the left side and immediately below is determined. 4. The optical information recording method according to claim 2, wherein the time width of the leading pulse corresponding to a portion below the diagonal line to the right is determined by utilizing the thermal interference characteristic of the recording film. The optical information recording method is characterized in that the determination is made by using the time width of each of the leading pulses on the right side and immediately above. 5. The optical information recording method according to claim 2, wherein the time width of the leading pulse corresponding to a portion above or below the right-downward diagonal line is determined by utilizing the thermal interference characteristic of the recording film. An optical information recording method characterized in that the determination is made symmetrically on the above table. 6. The optical information recording method according to claim 2, wherein the time width of the first pulse on the diagonal line to the right is:
When information is recorded using a (1,7) RLL code, the time of the head pulse that maximizes the carrier-to-noise ratio when both the mark length to be recorded and the previous space length are 4T (T is a clock period). An optical information recording method having a width. 7. The optical information recording method according to claim 1, which is optimal even from a writable optical information recording medium in which a recording pulse standard condition for specifying the position of a recording pulse is not recorded in advance. An optical information recording device, characterized in that it is configured so as to determine various recording pulse conditions. 8. An optical information recording medium, on which an optimum recording pulse condition determined by the optical information recording method according to claim 1 is recorded. 9. The optical information recording medium according to claim 8, wherein the recording film of the optical information recording medium is Sb and Te, or G.
An optical information recording medium comprising e, Sb, and Te as main raw materials.