KR100782862B1 - Apparatus for recording data on an optical recording medium - Google Patents

Abstract

A method and apparatus for recording data on an optical record carrier are disclosed.

According to the present invention, a method of recording data on an optical recording medium forms marks or forms spaces using a recording waveform having an erase pattern including multiple pulses. This suppresses the distortion of the mark shape and at the same time improves the mark shape, thereby improving the recording / reproducing characteristics.

Description

Apparatus for recording data on an optical recording medium {Apparatus for recording data on an optical recording medium}

The present invention relates to a method and apparatus for recording data on an optical record carrier, and more particularly, to a method and apparatus for recording digital data by forming a mark on an optical disk.

Recording data on an optical disc, which is one of the optical record carriers, means that marks are formed on tracks formed on the optical disc. In the case of a read-only disc such as a CD-ROM, a DVD-ROM, or the like, the mark is formed of a pit. In the case of a recordable disc such as a CD-R / RW, DVD-R / RW / RAM, a recording layer is coated with a phase change film that changes crystalline or amorphous depending on temperature, and a mark is formed through the phase change of the phase change film.

In terms of signal detection, a data recording method may be divided into a mark edge recording method and a mark position recording method. According to the mark position recording method, the amplitude of the detected RF signal is changed from positive / negative to negative / positive at the position where the mark is recorded. According to the mark edge recording method, the amplitude of the detected RF signal is changed from positive / negative to negative / positive at both edges of the mark. Therefore, accurately recording the edges of the marks is an important factor in improving the quality of the reproduction signal.

However, in the case of a disk coated with a phase change film, the shape of the disk according to the conventional recording method is observed depending on the length of the mark or the spacing of the marks, that is, the length of the space. It can be seen that appears differently. In other words, the end of the mark is formed larger than the leading edge of the mark, thereby degrading the recording / reproducing characteristic. This is more so because of thermal accumulation when the length of the recording mark is relatively long.

1 is a reference diagram showing a recording waveform according to the conventional method.

Referring to FIG. 1, various recording waveforms (a), (b) and (c) are shown for recording Non Return to Zero Inverted (NRZI) data. The recording waveforms (a) are for DVD-RAM, and the recording waveforms (b) and (c) are for DVD + RW. Here, T means a period of the reference clock. According to the mark edge recording method, the high level of NRZI data is recorded as a mark and the low level is formed as a space. The recording waveform used to record the mark is called a recording pattern, and the recording waveform used to form a space (used to erase the mark) is called an erase pattern. Conventional recording waveforms (a), (b) and (c) use multi-pulse as the recording pattern, and adjust the power level of each pulse to four levels of Ppeak, Pb1, Pb2 and Pb3, As described above, the power of the erase pattern is kept constant at a predetermined DC level.

As such, since the erase pattern included in the conventional recording waveform maintains the DC level constant for a predetermined time, heat of about 0 to 200 ° C. is continuously applied to the corresponding area. Therefore, the repetitive recording of a plurality of times causes a problem of deterioration and distortion in the shape of the mark, which significantly reduces the recording / reproducing characteristics. In particular, as the high density and high speed for recording more data on the disk proceeds, the period T of the reference clock decreases, which is more so in an environment in which thermal interference between pulses constituting the recording waveform becomes large.

On the other hand, conventionally, different recording waveforms are used depending on the type of optical disc, in particular DVD-RAM, DVD + RW and the like. This is because the characteristics of the recording film are different. The use of different recording waveforms for each disc is a particular problem when manufacturing a multi-drive capable of recording / reproducing discs of all standards. This is because the multi-drive must be able to implement various types of recording waveforms. This leads to an increase in costs.

This is to suppress the distortion of the mark shape due to thermal interference and heat accumulation between adjacent marks when data is written to the optical disc and to improve the mark shape.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is a method of recording data with a recording waveform which can more suppress the distortion of the shape of the first and the end of the mark and can suppress the deterioration due to repeated recording and To provide a device.

It is another object of the present invention to provide a method and apparatus for recording data in a recording waveform having an erase pattern which can further improve the shape of the mark.

It is still another object of the present invention to provide a method and apparatus for recording data in a recording waveform applicable to a disc having a recording film of various characteristics.

As described above, according to the present invention, a method and apparatus for recording data using a recording waveform which suppresses distortion of the mark shape due to thermal interference and heat accumulation between adjacent marks during recording, and at the same time improves the mark shape. Is provided. As a result, the recording / reproducing characteristic is improved.

The above object is, according to the present invention, in a method for recording data on an optical recording medium, (b) forming a mark or forming a space using a recording waveform having an erase pattern comprising multiple pulses; It is achieved by a method comprising a.

Step (b) is based on Run Length Limited (RLL) (2, 10) and preferably records a first level of predetermined NRZI data as a macro and a second level as a space.

On the other hand, the above object is a method for recording data on an optical recording medium, comprising: (a) generating channel modulated digital data; (b) generating a recording waveform comprising an erase pattern comprising multiple pulses; And (c) forming the first level of the digital data into a mark and forming the second level into a space using the generated recording waveform.

Preferably, steps (a), (b) and (c) are based on RLL (2,10) or RLL (1,7).

Most preferably, the power level of the leading pulse of the erase pattern is the low level of the multi-pulse and the power level of the last pulse is the high level, and the power level of the leading pulse of the erase pattern is the high level of the multi-pulse and of the last pulse. The power level is a high level, or the power level of the leading pulse of the erase pattern is the low level of the multi-pulse and the power level of the last pulse is the low level, or the power level of the leading pulse of the erase pattern is the high level of the multi-pulse. And the power level of the last pulse is low level.

Preferably, the ratio of the duration of the high level and the low level of the multi-pulse is 1 to 1 and the duration of the high level is 1/2 of a clock period.

The step (a) is a step of forming a first level of the predetermined NRZI data as a mark, and the step (b) is effective to form a second level of the NRZI data as a space.

The write signal includes a cooling pulse, and the erase pattern includes a portion of the cooling pulse. When the end point of the cooling pulse is less than or equal to 0.5T from the falling edge of the NRZI signal, it is effective to increase the duration of the leading pulse constituting the erase pattern to 0.5T or more.

Preferably, the unit pulse constituting the multi-pulse has a high level and a low level adjusted according to the duration of the leading pulse constituting the recording pattern.

More preferably, the recording pattern includes multiple pulses and the recording pattern has at least two power levels.

According to another aspect of the present invention, an object of the present invention is to provide an apparatus for recording data on an optical recording medium, comprising: a recording waveform generator for generating a recording waveform having an erase pattern including multiple pulses; And a pick-up section for irradiating light to the optical recording medium to form a mark or to form a space according to the generated recording waveform.

Preferably, the apparatus further includes a channel modulator for channel modulating data provided from the outside to generate NRZI data and output the NRZI data to the recording waveform generator.

The pickup unit includes a motor for rotating the optical recording medium; An optical head for irradiating laser light onto the optical record carrier or receiving laser light reflected from the optical record carrier;

A servo circuit for servo controlling the motor and the optical head; And a laser driving circuit for driving a laser provided in the optical head.

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

2 is a block diagram of a recording apparatus according to a preferred embodiment of the present invention.

Referring to FIG. 2, a recording apparatus is an apparatus for recording data by forming a mark or a space on an optical recording medium 200. The pickup apparatus 1, the recording waveform generating unit 2, and the channel modulating unit 3 are provided. ).

The channel modulator 3 modulates data input from the outside into channel bit strings. The recording waveform generating unit 2 receives a channel bit string and generates a recording waveform for recording it. The recording waveform generated according to the present invention includes an erase pattern with erase multi pulses. Detailed description of the recording waveform will be given later. The pickup unit 1 irradiates light to the optical recording medium 1 according to the generated recording waveform to form a mark or a space.

3 is an embodiment of FIG. 2. However, for the block performing the same function, the same reference numerals as those of FIG. 2 are assigned, and repeated description thereof will be omitted.

3, the recording apparatus includes a pickup section 1, a recording waveform generating circuit 2, and a channel changer 3. As shown in FIG. The pickup unit 1 includes a motor 11 for rotating the optical disk 200, an optical head 13 for irradiating laser light to the optical disk 200 or receiving laser light reflected from the optical disk 200. ), A servo circuit 12 for servo control of the motor 1 and the optical head 13, and a laser driving circuit 14 for driving a laser (not shown) provided in the optical head 13.

The channel modulator 3 outputs NRZI (Non Return to Zero Inverted) data by modulating the input data into a channel bit string. The recording waveform generating circuit 2 generates a recording waveform for recording NRZI data and provides it to the laser driving circuit 14 provided in the pickup section 1.

The laser drive circuit 14 forms a mark or a space on the optical disk 200 by controlling the laser using the received recording waveform.

4 is an example of a recording waveform generated by the recording waveform generating circuit 2.

Referring to FIG. 4, NRZI data depends on the modulation scheme of the channel modulator 3. That is, when modulating with the Run Length Limited (RLL) (2,10) series, that is, the minimum mark according to EFM (Eight to fourteen Modulation), EFM + (Eight to fourteen Modulation plus), D (8-15) and Dual modulation The length is 3T and the maximum mark length is 11T. Here, D (8-15) refers to a modulation scheme published by ODS (Optical Data Storage) in 2001 in "Optical Disc Recording System of 25GB Capacity." Dual modulation is applied by the applicant of September 30, 1999 and published on November 25, 2000, Korean Patent Application No. 99-42032 "RLL code placement method with improved DC suppression capability, modulation demodulation method and Demodulation device ". When recording using the RLL (1,7) series, the minimum recording mark is 2T and the maximum recording mark is 8T.

When the high level of the NRZI data is formed as a mark and the low level is formed as a space, the recording waveform has a recording pattern for recording a mark having a length of 7T, an erase pattern for forming a space having a length of 3T, and a length of 3T. And a recording pattern for recording the mark.

The recording pattern is composed of pulse trains. The erase pattern is also composed of pulse trains, as shown in section F. FIG. Tmp indicates the width of the multi pulses constituting the recording pattern. Here, the multi-pulse refers to at least one pulse having the same width and the magnitude of the power. In this embodiment, Tmp is 0.5T. Tlp indicates the width of the last pulse constituting the recording pattern. Tcl refers to the duration of the cooling pulse. Cooling pulses exist over the write pattern and the erase pattern. Temp refers to the width of an erase multi pulse constituting the erase pattern. In this embodiment, Temp is 0.5T. Tsfp means the time from the point at which the NRZI data is switched from the low level to the high level until the start of the first pulse constituting the recording pattern. Tsfp affects the power level of the erase pattern. That is, as shown, when Tsfp is larger than 0.5T, when the multi-pulse included in the erase pattern ends at the low level Pb1, the subsequent Tsfp starts at the high level Pb2 of the multi-pulse. In contrast, when Tsfp is less than 0.5T, when the multi-pulse included in the erase pattern ends at the low level Pb1, the subsequent Tsfp continues to maintain the low-level Pb1 of the multi-pulse.

5 is another example of the recording waveform generated by the recording waveform generating circuit 2.

Referring to Fig. 5, when the high level of the NRZI data is formed as a mark and the low level is formed as a space, the recording waveform is a recording pattern for recording a mark having a length of 7T and an erase for forming a space having a length of 5T. A recording pattern for recording a pattern and a mark having a length of 3T.

Similarly, the recording pattern is composed of pulse trains. The erase pattern is also composed of pulse trains, as shown in section G. FIG. Tmp indicates the width of the multi pulses constituting the recording pattern. Multi-pulse refers to at least one pulse of the same width and power magnitude. In this embodiment, Tmp is 0.5T. Tlp indicates the width of the last pulse constituting the recording pattern. Tcl indicates the duration of the cooling pulse. Cooling pulses exist over the write pattern and the erase pattern. Temp refers to the width of an erase multi pulse constituting the erase pattern. In this embodiment, Temp is 0.5T. Tsfp means the time from the point at which the NRZI data is switched from the low level to the high level until the start of the first pulse constituting the recording pattern. Tsfp affects the power level of the erase pattern. That is, as shown, when Tsfp is larger than 0.5T, when the multi-pulse included in the erase pattern ends at the low level Pb1, the subsequent Tsfp starts at the high level Pb2 of the multi-pulse. In contrast, when Tsfp is less than 0.5T, when the multi-pulse included in the erase pattern ends at the low level Pb1, the subsequent Tsfp continues to maintain the low-level Pb1 of the multi-pulse.

6 is a waveform diagram illustrating four types of erase patterns according to an exemplary embodiment of the present invention.

Referring to Figure 6, the erase pattern according to the present invention is classified into four types: (a) LH, (b) HH, (c) HL and (d) LL. Circles are indicated to facilitate differentiation between the erase patterns. First, (a) LH is equal to the low level Pb1 of the erase multi-pulse following the power of the leading pulse constituting the erase pattern, and the last erase multi-pulse constituting the erase pattern ends at the low level Pb1, and then the power level of the subsequent Tsfp is It is the same as the high level Pb2 of the erase multi-pulse. (b) HH is equal to the high level Pb2 of the erase multi-pulse followed by the power of the leading pulse constituting the erase pattern, and the level of Tsfp followed by the last erase multi-pulse constituting the erase pattern ends at the high-level Pb2. It is when the high level of Pb2 lasts. (c) HL is equal to the high level Pb2 of the erased multi-pulse following the power of the leading pulse constituting the erase pattern, and the level of Tsfp followed by the last erased multi-pulse constituting the erase pattern ends at the high-level Pb2. It is equal to the low level of Pb1. Finally, (d) LL is equal to the low level Pb1 of the erase multi-pulse following the power of the leading pulse constituting the erase pattern, and the level of Tsfp following the last erase multi-pulse constituting the erase pattern ends at the low level Pb1. This is when the low level Pb1 of the erase multi-pulse is continued.

7 is another examples of (a) LH of FIG. 6.

Referring to FIG. 7, (e) LH2 is the same as (a) LH of FIG. 6, but the values of the duration Temp1 of the high level Pb2 of the erase multi-pulse constituting one cycle and the duration Temp2 of the low level Pb1 are 0.7, respectively. Different from T and 0.3T. (f) LH3 is also the same as LH in FIG. 6, but the duration Temp of the high level Pb2 and the low level Pb1 of the erase multi-pulse is 1.0T. Here, the ratio of the duration Temp1 of the high level Pb2 of the erase multi-pulse constituting one cycle to the duration Temp2 of the low level Pb1 can be variously changed to m: n (m, n is an integer).

As such, the recording waveform according to the present invention has an erase pattern including the erase multi-pulse whose power has a high level Pb1 and a low level Pb2, thereby reducing distortion at the end of the mark and improving reproduction characteristics. In particular, the recording waveforms shown in the above embodiments are suitable for the thermal characteristics of the disk 200 by adjusting the durations of the high level Pb1 and the low level Pb2 of the erase multi-pulse within the range of 0.25 to 0.75T with respect to the clock period T. This is even more so because the duration was chosen and configured.

On the other hand, the information (type information) relating to these four types of erase patterns can be recorded in the lead-in area of the recordable disc or loaded as one of the header information in the wobble signal. Therefore, when recording data, the recording apparatus can read the type information from the lead-in area or the wobble signal to generate the corresponding recording waveform to form marks and spaces.

Furthermore, the four types of erase patterns can be used as symbols indicating the speed of the disc or the type of the mark in recording and reproducing. For example, it can display information that "a disc using an LH type erase pattern has a double speed of 20".

In order to examine the effect of the present invention, the shape of the recorded mark was observed through simulation. The structure used for the simulation is shown in the following [Table 1]. The disk used has a four-layer film structure.

Board Dielectric film Recording film Dielectric film Reflector Material PC ZnS-SiO2 Sb-Te eutectic ZnS-SiO2 Ag alloy thickness 0.6 mm 128 nm 14 nm 16 nm 30 nm

Simulation conditions were set to wavelength 405nm, numerical aperture NA 0.65, and linear velocity 6m / s. In order to observe the mark shape, the 8T mark was recorded again after the 8T mark was recorded so that 4T overlapped. 8 to 10 show the results of comparing mark shapes in the case of using the conventional recording waveform and in the case of using the recording waveform according to the present invention. (A) shows a mark formed by the simulation, (b) shows a mark formed by the recording waveform according to the present invention on (a) and (c) shows the mark formed by the conventional recording waveform on (a). Indicates the formed mark. Similarly, Fig. 9 (d) shows a mark formed by simulation, (e) shows a mark formed by a recording waveform having an erase pattern according to the present invention on (d), and (f) shows a conventional mark on (d). A mark formed by a recording waveform having a DC erase pattern in accordance with FIG. Fig. 10 (g) shows a mark formed by the simulation, (h) shows after erasing the mark of (g) with the erase pattern according to the present invention, and (i) shows a conventional DC erase on (g). It shows after erasing with a pattern.

[Table 2] shows the parameters of the thin film used in the simulation for thermal analysis.

Material λ = 405 nm C (J / cm ³ K) k (W / cmK) n k ZnS-SiO2 2.300 0.000 2.055 0.0058 Sb-Te eutectic (crystal) 1.650 3.150 1.285 0.0060 Sb-Te eutectic (amorphous) 2.900 2.950 1.285 0.0060 Ag alloy 0.170 2.070 2.450 0.2000

Referring back to the simulation results of FIGS. 8 to 10, the erase pattern according to the present invention of (b) compared to the end of the mark formed by the recording waveform having the conventional DC erase pattern of the conventional scheme of FIG. It can be seen that those of marks formed by recording waveforms having a better quality are better. It can be seen that the shape of the first part of the mark is better by using the erasure pattern according to the present invention as in the end part as shown in FIG. 9. From the above simulation results, it was confirmed that the shape of the mark is improved compared to the conventional one by using the recording waveform having the erase pattern composed of erase multi-pulses according to the present invention. The shape distortion of the mark can be further reduced by adjusting the shape, width, and power level of the erase multi-pulse.

To experimentally verify the effects of the present invention, a DVD evaluator with a laser wavelength of 650 nm and a numerical aperture of 0.6 0.6 is used to obtain the recording waveforms shown in FIGS. 4 and 5 on 4.7 GB DVD-RAM and 4.7 GB DVD-RW discs. The parameters, ie duration and power level, were obtained, and then repeated recording / playback characteristics were compared with the conventional method.

11 to 15 are graphs showing characteristics of the DVD-RAM.

(A) and (b) of FIG. 11 illustrate jitter characteristics according to recording power and erasing power for the leading edge, trailing edge, and both edges of a mark in conventional DC erasing. Represent each. From (a) and (b), 14.5 mW of recording power and 6 mW of erasing power were selected.

12 and 13 show the measured results for conventional DC cancellation.

Referring to (a), (b), (c) and 14 (a) and (b) of FIG. 12, Tsfp = 0.5T and 0.4T show the most preferable jitter characteristics for 3T and 4T or more, respectively. Tlp is good at 0.7T, and it can be seen that Tle has no significant difference in properties.

Based on the experimentally obtained parameters as described above, marks were formed from the recording waveforms having the above four types of erase patterns, and then the characteristics of the formed marks were measured. The results are as follows.

FIG. 14 shows the jitter characteristics of the four types of erase patterns shown in FIG.

Referring to FIG. 14A, it can be seen that the LH type is the best among the four types. Referring to (b) of FIG. 15, the jitter characteristic of the difference ΔPb (Pb2-Pb1) between the high level and the low level of the erase multi-pulse when the erase pattern is erased using the erase pattern composed of the erase multi-pulse according to the present invention is described. You can look. It can be seen that there is no big difference up to 5mW.

Fig. 15 shows the jitter characteristic of the result of repetitive recording / reproducing using a recording pulse having an erase pattern according to the present invention.

Referring to Fig. 15, as can be readily seen, the case of erasing using the erase multi-pulse according to the present invention shows an excellent result, particularly in terms of repeat recording characteristics.

16 to 20 are graphs showing characteristics of the DVD-RW.

(A) and (b) of FIG. 16 show jitter characteristics according to the recording power and the erasing power of the leading edge, trailing edge, and both edges of the mark in the conventional DC erasing, respectively. Indicates. From (a) and (b), 14.0 mW of recording power and 6 mW of erasing power were selected.

17 and 18 show the measured results for conventional DC cancellation.

Referring to FIGS. 17 and 18, Tsfp = 0.3T and 0.05T are most preferable for 3T and 4T or more, respectively, and Tlp is good at 0.55T, and Tle is 1.0T and 1.1T.

Based on the experimentally obtained parameters as described above, marks were formed from the recording waveforms having the above four types of erase patterns, and then the reproduction characteristics of the formed marks were measured. The results are as follows.

FIG. 19 shows the jitter characteristics of the four types of erase patterns shown in FIG.

19, it can be seen that the LH type is the best of the four types. In addition, when the erase pattern is erased using the erase pattern including the erase multi-pulse according to the present invention, the jitter characteristic may be described with respect to the difference ΔPb (Pb2-Pb1) between the high level and the low level of the erase multi-pulse. Since the characteristic deteriorates rapidly from 3 mW, 1 mW was selected as a condition of the repetitive recording / reproducing experiment.

Fig. 20 shows the jitter characteristic of the result of repeated recording / reproducing using a recording pulse having an erase pattern according to the present invention.

Referring to FIG. 20, as can be readily seen, the case of erasing using the erase multi-pulse according to the present invention shows an excellent result in particular in terms of repeat recording characteristics. However, after ~ 2000 times, the jitter characteristic deteriorates sharply. From this, it can be seen that the pulse erasing method according to the present invention is advantageous up to 1000 repeated recordings guaranteed by DVD-RW.

On the other hand, the above experiments used the EFM + modulation method because it was in accordance with the DVD format, but other modulation methods commonly used for recording recording marks stably, for example, RLL (1,7), D (8-15) The same result can be obtained by applying Dual modulation.

A recording method according to a preferred embodiment of the present invention based on the configuration as described above is as follows.

21 is a flowchart for explaining a recording method according to a preferred embodiment of the present invention.

Referring to FIG. 21, the recording apparatus receives data from an external source and modulates it to generate NRZI data (step 1801). Next, a write waveform having an erase pattern including an erase multi-pulse is generated (step 1802). Next, a mark or a space is formed on the optical disc 200 using the generated recording waveform (step 1803).

1 is a reference diagram showing a recording waveform according to the conventional method;

2 is a block diagram of a recording apparatus according to a preferred embodiment of the present invention;

3 is an embodiment of Figure 2,

4 is an example of a recording waveform generated by the recording waveform generating circuit 2,

5 is another example of a recording waveform generated by the recording waveform generating circuit 2,

6 is a waveform diagram illustrating four types of erase patterns according to an exemplary embodiment of the present invention;

7 is another examples of (a) LH of FIG.

8 to 10 show the shapes of the marks recorded through the simulation,

11 to 15 are graphs showing characteristics of a DVD-RAM;

16 to 20 are graphs showing characteristics of a DVD-RW;

21 is a flowchart for explaining a recording method according to a preferred embodiment of the present invention.

Claims (1)

An apparatus for recording data on an optical record carrier, A recording waveform generating unit for generating a recording waveform having a recording pattern including a leading pulse and a multi-pulse and an erase pattern including the leading pulse and a multi-pulse; And A pickup unit irradiating light to the optical recording medium to form a mark or form a space according to the generated recording waveform; The multi-pulse of the erase pattern has a high level and a low level, The power level of the head pulse of the erase pattern is set to the high level or the low level of the multi-pulse, And the power level of the section between the end of the erase pattern and the start point of the start pulse of the write pattern is set to the high or low level of the multi-pulse.

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