KR100577267B1 - Recording Method of Phase-change Optical Disk - Google Patents

Abstract

The present invention relates to a recording method of a phase change optical disk, comprising: a first recording pulse waveform having only a first pulse 2FP, a second recording pulse waveform having a first pulse 3FP and a last pulse 3LP, and a first pulse 4; 8FP), the recording marks 2T, 3T, 4-8T are recorded on the phase change optical disk using a third recording pulse waveform having a multi-pulse (4-8MP) and a last pulse (4-8LP) in sequence. In order to improve the edge jitter characteristic of the 4-8T mark, a multi-pulse (4-8MP) of the third recording pulse waveform is shifted in all directions with respect to the reference clock of the multi-pulse to form a recording pulse waveform. In a recording method of a phase change optical disk recorded using this recording pulse waveform, the start position of the last pulse 3LP of the second recording pulse waveform and the start of the last pulse 4 to 8LP of the third recording pulse waveform. Where these last pulses (3LP, 4 to 8LP), respectively, to be rearwardly shifted by a time t from the start position of the reference clock for each.

Phase change optical disc recording, jitter characteristics

Description

Recording Method of Phase-change Optical Disk

1 is a view showing a conventional recording pulse waveform;

2A is a diagram schematically showing a recording pulse waveform of a conventional 2-8T mark;

Figure 2b shows the waveform of the 2-8T mark when the multi-pulse (4-8MP) of the 4-8T mark is moved forward (right side) than the reference clock to improve the leading edge characteristics of the conventional 4-8T mark. Schematic drawing,

FIG. 2C is a diagram showing a tap photo of 2 to 8T marks when recording using the recording pulse waveform of FIG. 2A; FIG.

FIG. 2D is a diagram showing a tap photo of 2 to 8T marks when recorded using the recording pulse waveform of FIG. 2B; FIG.

3A is a diagram showing recording pulse waveforms of marks 2-4T according to the present invention;

FIG. 3B is a diagram showing a tap photo of 2 to 4T marks when recording using the recording pulse waveform of FIG. 3A; FIG.

4 (a) and 4 (b) are graphs showing the jitter of the number of direct overwrites when evaluated after recording using the recording pulse waveform and the conventional recording pulse waveform of the present invention, respectively;

5 (a) and 5 (b) are graphs showing power margins when evaluated after recording using the recording pulse waveform and the conventional recording pulse waveform of the present invention, respectively;

6 (a) and 6 (b) are graphs showing the tenant tilt margins of jitter when the evaluation is performed after recording using the recording pulse waveform and the conventional recording pulse waveform of the present invention, respectively;

7 (a) and 7 (b) are graphs showing the radial tilt margins of the jitter when the recording is performed using the recording pulse waveform and the conventional recording pulse waveform of the present invention and then evaluated.

8 is a schematic cross-sectional view of a phase conversion optical disk.

* Description of Major Reference Codes *

11 substrate 12 reflective layer

13: lower dielectric protective layer 14: lower interface layer

15: recording layer 16: upper interface layer

17: upper dielectric protective layer 18: polycarbonate cover sheet

The present invention relates to a recording method of a phase change optical disc, and more particularly, to a recording method of a phase change optical disc for improving the repetitive recording characteristics of an optical disc.

With the advent of the multimedia era, which covers video signals, audio signals, and computer data signals including moving and still images, package media (e.g., various discs including CDs, DVDs) are widely available. The same trend is expected to be more prominent.

Package media, such as compact discs (CDs) and digital video (or multifunction) discs (DVDs), are largely composed of a substrate and a recording film and protective film for recording information. Among these optical discs, read-only memory (ROM) optical discs have a servo, positional information, or fine grooves in the form of pits in the circumferential direction, and have a reflective layer.

On the other hand, in the case of a recordable optical disc capable of recording information only once, and in the case of a rewritable optical disc capable of repeatedly writing, reading and erasing information, in addition to the pre-pits and the reflective layer, It is composed of a recordable die, a phase change or magneto-optical recording layer, and a protective layer for protecting the recording layer. Such repeatable discs have recently been highly capacityd and are expected to be used as storage media for personal computers (PCs) in addition to audio, video, music files, and playback. In order to be able to record enough repetitive recording media for PC, it is necessary to be able to record and play a much larger number of repetitive recordings than for audio / video.

When a laser light source is irradiated to record or read information on these disks, the laser light is incident on a transparent polycarbonate substrate having a thickness of 0.6 mm or more in the above-described conventional optical disk, but recently, a short wavelength of blue band for high density recording ( 405 nm) When a laser is incident using a high numerical aperture (NA) objective lens, it passes through a cover layer of about 0.1 mm, and enters in the order of a protective layer, an information recording layer on which information is recorded, and a reflective layer. And a disk structure which is reflected by these multilayer films and returns to the photosensor (detector; generally photodiode).

In a phase change method of an iterative recording type optical disc, information is recorded as an amorphous mark on a crystalline matrix. In order to generate the amorphous mark, a laser must be irradiated. However, since the shape of the mark cannot be adjusted well due to heat accumulated when using a single pulse, a multi pulse as shown in FIG. 1 will be used. Doing.

FIG. 1 shows a conventional general recording pulse waveform, which defines three different laser power levels. The three power levels are erase power (Pe: Erase power) for erasing portions except for the write power level (Pw: Write power), which is the peak power of a pulse, and an overwrite mark, to make a crystalline space. Level, there is a bottom power (Pb: bottom power) level that defines the lowest power of the laser pulses.

In addition, FP is the first pulse, LE is the leading erase power time duration, MP is the Multi Pulse or Center Pulse, LP is the Last Pulse, TE Is a trailing cooling period deviation from a negative NRZI ending position. For example, 3FP is a first pulse of 3T mark, and 4-8MP is a 4-8T mark of multi-pulse. , 2TE represents the trailing cooling period deviation of the 2T mark, and 4-8LP represents the last pulse of the 4-8T mark.

Generally, the process based composition used for BD (Blue-ray Disc) recording using the blue band wavelength has growth dominant characteristics and the size of recording pulse width or cooling pulse width. The shape of the mark changes sensitively according to the position of each pulse.

Fig. 2A shows a conventional recording pulse waveform of 2T to 8T marks, in which all MP and LP positions are aligned with the rising edge of the reference clock. The appearance of the 2-8T mark when recorded with the laser pulse in this case is shown in Figure 2d. In this case, the trailing edge has a clear boundary between the crystalline and the amorphous phase than the leading edge, and thus the signal difference clearly appears at the boundary when the laser reads back the laser.

The recording principle of the phase change optical disk is to melt the crystalline and cool it at a high speed so that the melted part becomes amorphous. If the cooling speed is slow, the crystalline part grows from the adjacent part and reduces the part that can become amorphous.

In the conventional recording method, since the cooling rate is decreased due to the heat applied by 4-8MP after 4-8FP of 4-8T, the amorphous area of the leading edge portion is reduced, so that the trailing edge portion is mostly used. The jitter characteristic becomes worse.

In order to improve this, as shown in FIG. 2B, by moving the 4-8MP following the 4-8FP to the right with respect to the 4-8T mark, the heating time by 4-8MP is delayed, as shown in FIG. 2C. As a result, the amount of crystalline growth in amorphous phase is reduced, thereby improving the jitter characteristic at the leading edge of each 4-8T mark.

However, as described above, when the multi-pulse (4-8MP) of the 4T mark is moved to the right to improve the jitter characteristics of the leading edges of the 4-8T marks, the leading edges of the 4-8T marks become wider in the amorphous area. This produces the effect of shifting to the left, which results in jitter reduction due to an imbalance in the occurrence position between the large marks of 4 to 8T and the small marks of 2T and 3T.

Accordingly, it is an object of the present invention to provide a method for recording a phase change type optical disc to reduce or eliminate the increase in jitter derived when the multi-pulse of the 4-8T mark is moved to improve the leading edge characteristics of the 4-8T mark. It is for.

The recording method of the phase change optical disk according to the present invention for achieving the above object includes a first recording pulse waveform of 2T (T is a period of a reference clock) mark having only a first pulse (2FP), a first pulse (3FP) and a last pulse. 2nd recording pulse waveform of 3T mark which has (3LP), and 3rd recording of 4-8T mark which has the first pulse (4-8FP), the multi pulse (4-8MP), and the last pulse (4-8LP) sequentially When recording the corresponding marks (2T, 3T, 4-8T) on the phase change type optical disk using a pulse waveform, multi-pulse of the third recording pulse waveform to improve the jitter characteristics of the edges of the 4-8T marks. A recording method of a phase change type optical disc in which (4 to 8 MP) is formed by shifting the recording pulse waveform in the omnidirectional direction with respect to the reference clock of the multi-pulse, and recording using the recording pulse waveform, wherein at least the second recording pulse waveform Start position of last pulse (3LP) of By the time t than to the start position of the reference clock of the last pulse (3LP) it is characterized in that the formation is shifted to the rear.

According to another aspect of the present invention, a method for recording a phase change optical disk includes a first recording pulse waveform, a first pulse 3FP, and a last pulse 3LP having a 2T (T is a reference clock period) mark having only a first pulse 2FP. The second recording pulse waveform of the 3T mark having < RTI ID = 0.0 > 1) < / RTI > and the third of the 4-8T mark having the first pulse 4-8FP, the multi-pulse or the center pulse 4-8MP and the last pulse 4-8LP sequentially. When recording the corresponding marks (2T, 3T, 4-8T) on the phase change type optical disk using the recording pulse waveform, a third recording pulse waveform is used to improve the jitter characteristic of the edge of the 4-8T mark. A recording method of a phase change type optical disc in which a multi-pulse (4-8MP) is shifted in all directions with respect to the reference clock of this multi-pulse to form a recording pulse waveform, and the recording is performed using the recording pulse waveform. Last pulse of 2nd recording pulse waveform (3LP ) And the start positions of the last pulses 4 to 8LP of the third recording pulse waveform are shifted backwards by a time t from the start positions of the reference clocks for each of them.

Preferably the time t is in the range 0 <t ≦ 3 / 16T.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 3A shows a pulse waveform for implementing one embodiment of the present invention, and Fig. 3B shows a tab photo of a recording mark recorded using the pulse waveform.

As shown in FIG. 3A, the pulse waveform according to the embodiment of the present invention has a starting position of the multi-pulse (4-8MP) of the 4-8T mark at a predetermined time forward (a predetermined time) than the reference clock of the multi-pulse (4-8MP). In the recording method of a phase change optical disk for recording with a recording pulse waveform moved in the right direction in Fig. 3A, the last multi-pulse 3LP of 3T mark and the last pulse 4LP of 4-8T mark (represented by 4T mark). ) Is recorded on the phase change optical disk by using a recording pulse waveform shifted from the starting edge of each rising edge to the rear of the reference clock by a predetermined time t (0 <t <3 / 16T). do. Step photographs of 2T, 3T, and 4T at the time of recording using the above recording pulse waveform are as shown in Fig. 3B.

The recording pulse waveform according to the embodiment described above is an example in which the recording pulse waveforms of the 3T and 4T marks are modified. However, the present invention is not limited thereto, and the starting position of only the last pulse 3LP in the recording pulse waveform of the 3T mark is not limited thereto. May be used as the recording pulse waveform which is shifted backward by the time t (0 &lt; t &lt; 3 / 16T) with respect to the start position of the reference clock.

When data is recorded using such a recording pulse waveform, the multi-pulse (4-8MP) of the 4-8T mark is moved ahead of a predetermined time to improve the jitter characteristic of the leading edge of the 4-8T mark. When moving from the reference clock to the right), the position imbalance between the small 2T, 3T mark and the 4-8T mark is changed to 3T mark or 4 due to the effect that the leading edge of the 4-8T mark is moved backward (left in the drawing). By shifting the start position of the last pulse (3LP, 4-8LP) of the ~ 8T mark to the rear (left in Fig. 3a) by a predetermined time t (0 <t≤3 / 16T) from the start position of each reference clock. By compensating for the position imbalance, side effects of jitter increase due to the imbalance of the position occurring between the large marks 4 to 8T and the small marks 2T and 3T can be solved.

(Example)

Fig. 8 shows the Ag alloy reflective layer 12 and the lower dielectric layer of ZnS-SiO ₂ on a dounut-shaped polycarbonate substrate 11 having an inner diameter of 15 mm, an outer diameter of 120 mm, a thickness of 1.1 mm, and a track pitch of 0.32 um (with land and groove). Protective layer 13, lower interface layer 14, recording layer 15 formed of an alloy of Ge-Sb-Te series, upper interface layer 16, and upper dielectric protective layer 17 of ZnS-SiO ₂ The multilayer thin film formed by laminating | stacking is formed. Then, a 80 μm polycarbonate cover sheet 18 is bonded to the multilayer thin film layer with a UV resin of 20 μm to manufacture a phase change optical disc, and then the optical disc is initialized using an initialization device. Thereafter, the recording pulse waveform (FIG. 3A) for implementing the above-described present invention is recorded and reproduced using an optical disk driver and an evaluation equipment (for example, Pulstec's DDU-1000 equipment).

At this time, the recording and reproducing condition is as follows.

Channel Bit Clock = 132 MHz (1T = 7.5757 nano second)

Linear Velocity = 10.56 m / s

Disk Capacity = 23.3 GB / Single Side

Jitter Measuring Equipment: Yokogawa TA520

Sampling: 30,000

Reading Laser Power = 0.35㎽

Bottom Laser Power = 0.5㎽

Write Laser Power = 5.2㎽

Erase Laser Power = 1.9㎽

The position of the leading edge and trailing edge of the jitter is normalized to a channel bit length (CBL) in which the distribution of the deviation from the reference position in accordance with the PLL clock is normalized. In order to measure the N repetitive recording jitter, the waveform is recorded using a randomly mixed N-circuit random pulse waveform (2T, 3T, 4-8T) in one track.

(A) and (b) of FIG. 4, (a) and (b) of FIG. 5, (a) and (b) of FIG. 6, and (a) and (b) of FIG. The results of recording and evaluation using the recording and reproducing conditions of the above-described embodiment at the frequency and the disk rotational speed are shown as shown in FIGS. 4A, 5A, 6A, and 7A. Is evaluated after recording using the recording pulse waveform (FIG. 3A) of this invention, and FIG. 4 (b), FIG. 5 (b), FIG. 6 (b), and FIG. 7 (b) are 1x speed. The evaluation was performed after recording at double speed using a conventional general recording pulse waveform (FIG. 1) commonly used in the present invention. In each figure, the reference jitter for each recorded pulse waveform is 10% of the upper limit of jitter evaluated using conventional EQ (Equalizer), and 6.5% of the upper limit of jitter evaluated using limit EQ (in bold lines in each figure). Display).

As can be seen from (a) and (b) of FIG. 4, when the conventional recording pulse waveform (FIG. 1) is used, the jitter (%) of the direct overwrite cycle when using the conventional EQ (%) Although the portion exceeding the upper limit of 10% is generated, in the case of the present invention (Fig. 4 (a)) it can be seen that all located below the upper limit of 10%, which is the reference jitter, jitter characteristic is improved than the conventional one can confirm. 5 (a) and 5 (b) show the margins of the recording power Pw of the present invention and the conventional recording pulse waveform, respectively. As shown in FIG. When the conventional EQ is recorded and the conventional EQ is evaluated, the range with the reference jitter of 10% or less is 4.9 Hz to 5.7 Hz, but in the conventional case, the reference jitter value (%) in any power range is shown in FIG. It can be seen that it is exceeding).

6A and 6B show tangential tilt margins when the present invention and the conventional recording pulse waveform are used, respectively, and FIGS. 7A and 7B show the present invention and the prior art, respectively. The radial tilt margin when using the recording pulse waveform is shown.

As shown in (a) and (b) of FIG. 6, in the case of the present invention of FIG. 6 (a), the tangent tilt margin of jitter is in the range of -0.25 &lt; 6 (b), the jitter tangential tilt margin is significantly improved in the range of -0.1 &lt;

In addition, in the case of the present invention shown in FIG. 7A when evaluated by conventional EQ as shown in FIGS. 7A and 7B, the radial tilt margin of jitter is -0.8 <θ <0.75. In the conventional case illustrated in FIG. 7B, the radial tilt margin of jitter is larger in the case of the present invention, -0.75 &lt;

As described above, according to the present invention, the position of the small 2T, 3T mark, and the large 4-8T mark derived when the multi-pulse (4-8MP) of the 4-8T mark is moved to improve the leading edge characteristics of the 4-8T mark. The imbalance is shifted by shifting the start position of the last pulses (3LP, 4-8LP) of the 3T mark or the 4-8T mark backwards by a predetermined time t (0 <t≤3 / 16T) from the start position of each reference clock. There is an effect that the position imbalance can be reduced or eliminated by zooming.

Claims (4)

The first recording pulse waveform having only the first pulse 2FP, the second recording pulse waveform having the first pulse 3FP and the last pulse 3LP, the first pulse 4-8FP, the multi pulse 4-8MP, and the last. Improved leading edge jitter characteristics of the 4-8T marks when recording the corresponding recording marks 2T, 3T, 4-8T on the phase change optical disk using a third recording pulse waveform having the pulses 4-8LP sequentially. In order to make a recording pulse waveform, the multi pulses (4 to 8 MP) of the third recording pulse waveform are shifted in all directions with respect to the reference clock of the multi pulse to form a recording pulse waveform, and the recording is performed using the recording pulse waveform. In the recording method, And the start position of the last pulse (3LP) of the second recording pulse waveform is shifted backward by a time t from the start position of the reference clock with respect to the last pulse (3LP). The method of claim 1, And the time t is 0 &lt; t &lt; 3 / 16T (where T is the period of the reference clock). The first recording pulse waveform having only the first pulse 2FP, the second recording pulse waveform having the first pulse 3FP and the last pulse 3LP, the first pulse 4-8FP, the multi pulse 4-8MP, and the last. Improved leading edge jitter characteristics of the 4-8T marks when recording the corresponding recording marks 2T, 3T, 4-8T on the phase change optical disk using a third recording pulse waveform having the pulses 4-8LP sequentially. In order to make a recording pulse waveform, the multi pulses (4 to 8 MP) of the third recording pulse waveform are shifted in all directions with respect to the reference clock of the multi pulse to form a recording pulse waveform, and the recording is performed using the recording pulse waveform. In the recording method, The starting position of the last pulse 3LP of the second recording pulse waveform and the starting position of the last pulse 4-8LP of the third recording pulse waveform are the reference clocks for each of these last pulses 3LP, 4-8LP. The recording method of a phase change optical disc, characterized in that formed so as to be shifted rearward by each time t from the start position. The method of claim 3, wherein And the time t is 0 &lt; t &lt; 3 / 16T (where T is the period of the reference clock).

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