KR100813992B1 - Reproducing method of optical disc - Google Patents

Abstract

Disclosed is a method for reproducing an optical disc in which grooves and lands are formed on the entire lead-in area, user data area, and lead-out area of the disc, which can be manufactured under uniform conditions during manufacturing, and that a reliable reproduction signal can be obtained. have. The disclosed optical disc reproducing method includes a lead-in area, a user data area, and a lead-out area, wherein the lead-in area, the user data area, and the lead-out area are formed of grooves and lands, and at least one of the grooves and lands is read only data. A wobble is formed, and the wobble in the first area in the lead-in area, the second area in the user data area, and the third area in the lead-out area is reproduced by different modulation methods. As a method, information contained in a wobble of at least one of a first region, a second region, and a third region is irradiated by irradiating a light beam on an optical disk for recording or reproduction, and receiving a light beam reflected from the optical disk for recording or reproduction. It is characterized by reading.

Description

Reproducing method of optical disc

According to the present invention, grooves and lands can be formed on the entire surface including the lead-in area, the user data area, the lead-out area, and a predetermined area for a specific purpose, so as to produce a highly reliable recording / reproducing signal. The present invention relates to a method of reproducing an optical disc, which can be obtained.

In general, an optical disk is widely used as an information recording medium of an optical pickup apparatus for recording / reproducing information in a non-contact manner, and is used as a compact disk (CD) or a digital versitile disk (DVD) according to the information recording capacity. Are distinguished. Furthermore, DVD-based optical discs capable of recording, erasing and reproducing information include DVD-RAM (random access memory) and DVD-RW (rewritable).

As shown in FIG. 1, the DVD-RAM and DVD-RW discs have a lead-in area 10 in which read-only data such as the size of the disc, the number of track layers on the read surface, copy protection information, and the like are recorded, repeated playback and / or It can be divided into a recordable user data area 20 and a lead-out area 30 in which information related to other discs is recorded.

A portion of the lead-in area 10 and the lead-out area 30 (parts A and B) is enlarged to form a pit 15 in physical form, which is data for reproduction only. In the user data area 20, grooves 23 and lands 25 are alternately formed to record and / or reproduce information marks 27 along a predetermined track.

However, the biggest difference between DVD-RAM and DVD-RW is in the physical area for recording. In other words, the DVD-RAM records in both the lands 25 and the grooves 23, whereas the DVD-RW records only in the grooves 23 area. These two standards have the following problems.

First, in the case of DVD-RW, the recording state is the same physical structure as that of the DVD-ROM, which is a play-only optical disc, and the playback compatibility is excellent in a DVD-ROM drive or a DVD player. On the other hand, DVD-RAMs are incompatible because they require additional hardware modifications in order to play on DVD-ROMs in order to play on DVD-ROMs due to the phase difference according to the depths of the lands and grooves.

Second, in the case of recording on the groove in the DVD-RW, the groove depth is formed to be two times or more shallower than the DVD-RAM in consideration of the recording and reproduction characteristics and the injection characteristics. Here, when the read-only data is required for the lead-in area 10, the read-only data is formed in the form of a pit 15. Referring to FIG. 2, the amplitude ratio of the reproduction signal to the pit depth in units of λ / n is graphically shown with respect to the wavelength λ of the reproduction beam and the refractive index n of the disc.

In the case where the recording mark lengths are 3T and 14T with respect to the length T of the minimum recording mark, the amplitude ratio is m ₁ when the depth of the pit is about 0.06 (λ / n), which is the groove depth of the DVD-RW. , m ₂ , between 0.2 and 0.3. And when the depth of the pit is 0.25, the amplitude ratio appears to be close to approximately 1. Therefore, when the depth of the pit is λ / 12n which is the groove depth of the DVD-RW, the signal level is approximately 30% (1: 0.3) or less compared to the result at the λ / 4n depth. In this way, when the read-only data is formed as thin as the depth of the groove in the DVD-RAM, a reliable pit signal cannot be obtained.

Third, there is a need for a multilayer disc in which a plurality of recording layers are designed in the incident beam direction as shown in Fig. 3 to further increase the recording capacity. Thus, for example, in the case where a double recording layer having a first recording layer L0 and a second recording layer L1 is formed, recording light is emitted from the first recording layer L0 when recording is performed on the second recording layer L1. Passing through the layer, there is a difference in the optical power in the pit and the grooved area. In addition, when a physical header indicating a recording basic unit is used in the data area, a difference occurs in terms of transmittance since the physical header area always remains in a crystallized state unlike the area to be recorded.

Referring to FIG. 4, optical powers of the mirror area, the pit area, the groove area, and the groove area on which the mark is formed are calculated and shown in a graph. According to this graph, the shape of each area affects the optical power.

Table 1 below shows the conditions used in the optical power experiment.

  parameter    Condition   Wavelength (nm)    400   Numerical aperture (NA)    0.65 / 0.85   Mark length (㎛)    0.275 / 0.194   Modulation    EFM +   Track pitch (㎛)    0.30, 0.34, 0.38   reflectivity(%)    Rc = 25, Ra = 5

In the above table, Rc represents the reflectance of the crystalline portion in the recording layer, and Ra represents the reflectance of the amorphous portion, respectively. According to the experimental results, the optical power is reduced to the smallest in the mirror area, and gradually decreases in the order of the pit area, the groove area, and the mark formed groove. As a result, as shown in FIG. 3, the recording / reproducing beam 40 is applied to the boundary between the lead-in area of the first recording layer L0 and the data area of the groove, so that the beam is only applied to the groove. Compared with the case, the amount of light of the beam reaching the second recording layer L1 is changed. The groove in which the mark is formed in this way has a poor recording / reproduction since the recording power affects the recording power when data is recorded in the second recording layer in the double recording layer.

Furthermore, in order to reduce the spot size of the reproduction beam to increase the density, the numerical aperture NA must be increased. In this case, the problem with the dual recording layer, that is, the difference in optical power, becomes more severe as the numerical aperture becomes larger. Table 2 below analyzes the causes of the difference in optical power as the numerical aperture increases.

     Item   factor     Yes   Dual recording layer   Structure of the first recording layer Grooves, feet ...   High NA   The number of tracks over the beam NA 0.65: 85 track → NA 0.85: 160 track   Incident beam angle NA 0.65: 40.5 ° → NA 0.85: 58.2 °

As shown in Table 1, when grooves and pits are formed in the first recording layer of the dual recording layer, the higher the numerical aperture NA, the more the number of tracks that the beam extends to and the larger the incident angle of the incident beam. Will make you crazy.

Fourth, the disc structure is different in the lead-in (pit) / data area (groove) / lead-out (feet) area, and the manufacturing conditions are different, which leads to complicated manufacturing processes and lower yields. There is a problem that rises.

Accordingly, the present invention has been made to solve the above problems, and by forming all of the data area, the lead-in area and the lead-out area into grooves, the manufacturing conditions at the time of mastering are the same to improve the yield and manufacturing cost. An object of the present invention is to provide a method for reproducing.

It is also an object of the present invention to provide a method for reproducing an optical disk having an improved structure such that optical power is uniformly irradiated upon recording / reproducing on a disk having a multi-layer recording layer.

It is also an object of the present invention to provide a method for reproducing an optical disc having a read-only area and a recording / reproducing area in the lead-in area.

In order to achieve the above object, the optical disc reproducing method according to the present invention comprises a lead-in area, a user data area and a lead-out area, wherein the lead-in area, the user data area and the lead-out area are formed of grooves and lands. A wobble is formed in at least one of the groove and the land as reproduction-only data, and the wobble in the first area in the lead-in area, the second area in the user data area, and the third area in the lead-out area are mutually different. A method of reproducing a recording or reproducing optical disc formed by another modulation method, comprising: irradiating a light beam to the recording or reproducing optical disc, and receiving a light beam reflected from the recording or reproducing optical disc, thereby providing the first area and the second; And read information included in the wobble of at least one of the region and the third region. .

Information contained in the wobble is characterized in that the physical position information of the recording or playback optical disk.

The data of the user data area of the optical disc is recorded in at least one of a land and a groove.

The lead-in area of the optical disc is characterized by having a read-only area and a recording / reproducing area.

Further, a wobble is formed in the groove and / or land as reproduction-only data.

In addition, the weave in the lead-in area, the user data area and the lead-out area is characterized in that each formed by the same modulation method.

In addition, the weave in the lead-in area, the user data area or the lead-out area is characterized in that formed in different modulation schemes.

In addition, the modulation method of the wobble is characterized in that the QPSK.

In addition, the modulation method of the wobble is characterized by consisting of a wobble portion of a single frequency of a predetermined period and / or a non-wobble portion of a predetermined period.

In addition, the wobble modulation method is characterized in that the wobble frequency modulation (frequence modulation) method.

In addition, the wobble modulation method is characterized in that the wobble amplitude modulation (amplitude modulation) method.

In addition, the wobble modulation method is characterized in that the phase modulation (phase modulation) method.

In addition, the wobble modulation method is characterized in that the minimum shift keying (MSK) method for changing only the frequency of a portion of the continuous wobble.

The wobble modulation method may be a sawtooth wobble modulation method.

The wobble modulation method may include a QPSK method, a frequency modulation method, an amplitude modulation method, a combination of a single frequency wobble of a predetermined period and a non-wobble part of a predetermined period, a phase modulation method, an MSK method, and a sawtooth. At least one of the type modulation schemes, and the lead-in area and the lead-out area is characterized in that the wobble of the method different from the wobble modulation method of the user data area.

In addition, the optical disc is characterized by consisting of at least one recording layer.

A first wobble is formed in the read only area, and a second wobble of a modulation method different from the first wobble is formed in the recording / reproducing area.

The first wobble may include at least one of a QPSK method, a frequency modulation method, an amplitude modulation method, a combination of a single frequency wobble of a predetermined period and a non-wobble part of a predetermined period, a phase modulation method, an MSK method, and a sawtooth modulation method. The second wobble is a modulation method different from the first wobble.

The first wobble is a high frequency wobble, and the second wobble is a low frequency wobble.

In the reproduction-only area, a header field indicating address information is located at the head, trailing edge, or ECC recording unit boundary of the ECC recording unit.

In addition, the wobble formed in the header field is characterized in that the low frequency.

In the optical disc reproducing method according to the present invention, when a reproducing is performed on a multi-layer disc by reproducing an optical disc in which the lead-in area, the user data area, and the lead-out area are formed with grooves and lands, and the reproduction-only data is wobbled instead of pit, The optical power of can be made uniform.

Hereinafter, an optical disk according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 5, an optical disk according to the present invention is an optical disk including a lead-in area 100, a user data area 110, and a lead-out area 120. The entire disk area includes grooves 123 and lands 125. Characterized in that the configuration.

In this case, the user data may be recorded only in the groove 123 and may be recorded in both the groove 123 and the land 125.

On the other hand, when recording read-only data, wave-shaped wobble signals 105, which are signals of a specific frequency, are continuously recorded on the sidewalls of the grooves 123 and / or the lands 125 instead of pits. 5, the grooves 123 and the lands 125 are alternately formed in the lead-in and lead-out areas 100 and 130, and both sidewalls of the grooves 123 and the lands 125 are formed. The wobble 105 of the weave shape is formed in the. Then, when the portion E of FIG. 5, which is a part of the user data area 130, is enlarged, grooves 123 and lands 125 are alternately formed, and wobbles 105 are formed on both side walls of the grooves 123 and lands 125. ) Is formed. Here, the recording / reproducing beam 110 records or reproduces along the groove and / or the land track.

In forming the wobble, as shown in FIG. 6, a unidirectional wobble method may be used in which the wobble 105 'is formed only on one side of the land 125' or the groove 123 '. Alternatively, wobble may be formed on both sides of the groove 123 'and the land 125'.

In addition, FIG. 7 illustrates a method of recording data for reproduction only by mixing the wobble 127 and the land prepit 130 having pits formed at predetermined intervals on the land 125. The land prepit 130 is formed in a mirror-determined area when the disc substrate is manufactured, and the pickup device provided in the recording / reproducing apparatus can easily go to a desired position by the information recorded therein. In addition, the pickup apparatus can recognize, for example, a sector number, a sector type, a land / groove, etc. based on the information recorded in a land-prepit form, and can also perform servo control.

As described above, in the present invention, data for exclusive use of reproduction is recorded by the wobble signal instead of the pit so that the physical shape is uniform throughout the disc, so that the optical power decreases less in the case of the multilayer recording layer.

8A shows an example of a modulation method of the wobble signal according to the present invention. This modulation method stores data by changing the frequency of the wobble 105 (105 ') by frequency modulation. For example, data is recorded as a combination of bits "0" and "1", and the frequency of the wobble when the bit takes a logic "0" and the frequency of the wobble when the bit takes a logic "1". Data is recorded by doing differently, where the "0" bit and the "1" bit are recognized as the frequency at the "0" bit is greater than the frequency at the "1" bit.

As another example, there is a phase modulation scheme as illustrated in FIG. 8B. This is to record data by changing the phase of the wobble 105 (105 '). For example, data is recorded by changing the phase of the wobble when the bit takes the logic value "0" and the phase of the wobble when the bit takes the logic value "1". For example, data can be recorded by making a phase difference of 180 degrees out of phase of a wobble representing a "0" bit and a phase of a wobble representing a "1" bit.

Also, as shown in FIG. 8C, there is an amplitude modulation scheme. For example, data is recorded by varying the amplitude of the wobble when the bit takes the logic value "0" and the amplitude of the wobble when the bit takes the logic value "1".

In addition, as shown in FIG. 8D, a method of recording data by a Modified Amplitude Modulation (MAM) method including a combination of a wobble unit 135 and / or a non-wobble unit 137 having a predetermined period in a predetermined period may be described. It is available. Here, the wobble unit 135 is configured of a single frequency, the non-wobble unit 137 is a portion where the wobble is not formed. Thus, for example, data may be recorded by varying the length of the wobble part 135 or the non-wobble part 137.

In addition, as illustrated in FIG. 9, a method of recording by a QPSK (Qudarature Phase Shift Keying) method that modulates the phase of each wobble signal 140 by 90 ° may be used. Here, reference numeral 145 denotes a recording mark which is user data. In this manner, when recording the playback-only data by wobble, the user data and the playback-only data are stored together along the groove and / or the land track, thereby improving the use efficiency of the recording area of the disc.

Alternatively, as shown in FIG. 10, a minimum shift keying (MSK) method of changing only a frequency of a portion of a continuous wobble or a sawtooth wobble having a sawtooth-shaped wobble 150 as shown in FIG. 11. ) Can be adopted. The toothed wobble 150 has a "0" bit or a "1" bit depending on the shape of the portion 150a having a relatively high inclination and the portion 150b having a relatively low inclination. Meanwhile, as illustrated in FIG. 12, the track pitches TP1 and TP2 of the wobble may be configured differently to reduce crosstalk between tracks.

According to another embodiment of the present invention, as shown in FIG. 14, an optical disc in which the read only data is recorded by the first wobble is recorded in the lead-in area 100 and the second wobble is formed. The playback area 105 is provided. The first and second wobbles are configured to adopt different modulation schemes or to have different specifications for displaying the wobble. In other words, the first wobble includes at least one of the QPSK method, the frequency modulation method, the amplitude modulation method, a combination of a single frequency wobble of a predetermined period and a non-wobble part of a predetermined period, a phase modulation method, an MSK method, and a sawtooth wobble method. The second wobble is configured in any one manner, and the second wobble is configured in a different manner from the first wobble.

On the other hand, as shown in Fig. 13, the recording / reproducing area 105 has address information in the entire groove area, and in the reproduction-only area 103, a separate header field 101 indicating the address information and reproduction-only data. Field 102 may be provided. The header field 101 may be disposed at the head, tail or ECC recording unit boundary of the ECC recording unit. Here, the specification of the wobble of the header field 101 may be the same as or different from the specification of the wobble in the recordable / reproducible area or the wobble of the read only area. In particular, as shown in FIG. 14, the high frequency wobble is performed in the reproduction-only data field 102 of the reproduction-only area 103, and the wobble in the header field 101 and the recording / reproduction area 105 is low frequency. Wobbles may be formed. This is to prevent the reproduction signal from being bad when the address information in the header field 101 is recorded at high frequency.

In addition to the lead-in area 100, the data area 120, and the lead-out area 130, a predetermined area formed for a specific purpose may be further included in the optical disk according to the present invention.

Fig. 15 schematically shows a system for recording / reproducing an optical disc according to the present invention as described above. The optical disk recording / reproducing system includes a laser diode 150 for irradiating light, a collimating lens 152 for paralleling the light emitted from the laser diode 150, and a path for traveling the light according to the polarization direction of the incident light. A polarizing beam splitter 154, a quarter wave plate 156, and an objective lens 158 for focusing incident light onto the optical disk 160 are included. The light reflected by the optical disk 160 is reflected by the polarization beam splitter 154 and received by a photodetector, for example, a quadrant photodetector 162. The light received by the photodetector 162 is converted into an electrical signal and output to channel 1 which is detected as an RF signal and channel 2 which detects a wobble signal by a push-pull method. Here, H1, H2, H3, and H4 represent DC amplifiers, and Ia, Ib, Ic, and Id represent first to fourth current signals output from the quadrature photodetector 162.

The optical disc of the present invention can form reproduction-only data by using various modulation methods as described above. In particular, the lead-in area 100, the lead-out area 130, and the user data area 120 may form a wobble signal by the same modulation scheme.

Alternatively, the wobble may be formed in the lead-in area 100, the user data area 120, or the lead-out area 130 by different modulation methods. For example, in the user data area 120, at least any one of a frequency modulation method, a phase modulation method, an amplitude modulation method, a mixing method of a wobble part and a non-wobble part, a QPSK method, a phase modulation method, an MSK method, and a sawtooth wobble method. One modulation method may be used, and the lead-in area 100 and the lead-out area 130 may form a wobble by a modulation method different from the modulation method employed in the user data area 120.

On the other hand, in the present invention, a disk having at least one recording layer can be configured to improve the recording capacity. For example, in a disc composed of a double layer of a first recording layer and a second recording layer, in the present invention, as described above, all regions are formed by grooves and lands, and read-only data is uniformly formed by wobble. The difference in optical power does not occur in the boundary area between the in-region or the lead-out area and the user data area.

1 is an enlarged view of a conventional optical disc and part A, part B and part C,

2 is a graph showing an amplitude ratio of a reproduction signal to a pit depth;

3 is a partial cross-sectional view of a conventional optical disk,

4 is a graph showing optical power according to various cases;

5 is an enlarged view of an optical disc and a C part, a D part, and an E part according to the present invention;

6 is a diagram illustrating a unilateral wobbling method of an optical disk according to a temporary embodiment of the present invention;

7 is a diagram illustrating a wobble and land-prepit mixing scheme of an optical disc according to another embodiment of the present invention;

8A illustrates waveforms obtained from wobble due to frequency modulation according to another embodiment of the present invention;

8B is a view showing waveforms obtained from wobble due to phase modulation according to another embodiment of the present invention;

8C is a view showing waveforms obtained from a wobble by amplitude modulation according to another embodiment of the present invention;

FIG. 8D illustrates waveforms obtained from wobble by MAM modulation according to another embodiment of the present invention; FIG.

9 illustrates a QPSK scheme according to another embodiment of the present invention.

10, 11 and 12 illustrate waveforms obtained from wobble according to another embodiment of the present invention.

13 and 14 are views showing the arrangement of a header field indicating an address and a reproduction-only data in an area where reproduction-only data is wobbled in the optical disc according to the present invention;

Fig. 15 is a diagram schematically showing a recording / reproducing system of an optical disc according to the present invention.

<Explanation of symbols for main parts of the drawings>

100 ... Lead-in Area 105 ... Wobble

120 ... User data area 123,123 '... Groove

125,125 '... Land 130 ... Lead-out area

135 Wobble Part 137 Non Wobble Part

Claims (5)

A wobble including a lead-in area, a user data area, and a lead-out area, wherein the lead-in area, the user data area, and the lead-out area are formed of grooves and lands, and formed in at least one of the grooves and lands as reproduction-only data. Is formed, wherein a weave in the first area in the lead-in area, the second area in the user data area, and the third area in the lead-out area is formed by a different modulation method. By irradiating a light beam to the recording or reproducing optical disk and receiving the light beam reflected from the recording or reproducing optical disk, information contained in the wobble of at least one of the first region, the second region and the third region is obtained. An optical disc reproducing method, characterized in that for reading. The method of claim 1, And the information included in the wobble is physical position information of the recording or reproducing optical disc. The method according to claim 1 or 2, The modulation method of the wobble of the first area in the lead-in area includes a method of combining a quadrature phase shifting keying (QPSK) method, a wobble frequency modulation method, a wobble amplitude modulation method, a combination of a single frequency wobble of a predetermined period and a non-wobble part of a predetermined period, An optical disc reproducing method according to any one of a phase modulation method, a minimum shift keying (MSK) method, and a sawtooth wobble modulation method. The method according to claim 1 or 2, The modulation method of the wobble of the second area in the user data area includes a method of combining a quadrature phase shifting keying (QPSK) method, a wobble frequency modulation method, a wobble amplitude modulation method, a combination of a single frequency wobble of a predetermined period and a non-wobble part of a predetermined period, An optical disc reproducing method according to any one of a phase modulation method, a minimum shift keying (MSK) method, and a sawtooth wobble modulation method. The method according to claim 1 or 2, The modulation method of the wobble of the third area in the lead-out area may be a method of combining a quadrature phase shifting keying (QPSK) method, a wobble frequency modulation method, a wobble amplitude modulation method, a combination of a single frequency wobble of a predetermined period and a non-wobble part of a predetermined period, An optical disc reproducing method according to any one of a phase modulation method, a minimum shift keying (MSK) method, and a sawtooth wobble modulation method.

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