CN100547660C - Method and device for reproducing data of super-resolution information storage medium - Google Patents

Abstract

Provide a kind of reproduction to have method and the equipment thereof that is recorded in the data in the super resolution information storage medium less than the form of the mark of the size of the resolution characteristic of incident beam.Described data reproducing method comprises: will have first light beam of the resolution power that causes the super-resolution phenomenon and have second light beam irradiates of the resolution power that does not cause the super-resolution phenomenon to information storage medium; Detection is based on first reproducing signal of first light beam with based on second reproducing signal of second light beam; Compensate and calculate the time delay between first reproducing signal and second reproducing signal.Therefore, can be excluded from the signal of the external zones of the reconstruction beam point except super-resolution district reflection, thereby improve the reproducing signal characteristic.

Description

Method and device for reproducing data of super-resolution information storage medium

technical field

The present invention relates to a method and device for reproducing data recorded on a super-resolution information storage medium, and more particularly, to a method and device for reproducing data recorded on a super-resolution information storage medium, which can be obtained from The super-resolution information storage medium removes inter-symbol interference (ISI) to improve characteristics of reproduced signals.

Background technique

The optical recording medium is used as an information storage medium of an optical pickup that records and/or reproduces information in a non-contact manner. With the progress of industrial development, there is an urgent need for information recording media with greater recording density. Therefore, an optical recording medium capable of reproducing a recording mark having a spot diameter smaller than a laser beam spot by utilizing the super-resolution phenomenon is being developed.

Generally, when the wavelength of light used to reproduce data recorded on a recording medium is λ and the numerical aperture of the objective lens is NA, the limit of reproducible resolution becomes λ/4NA. In other words, since the light emitted from the light source cannot distinguish recording marks having a diameter smaller than λ/4NA from other recording marks, such data cannot often be reproduced.

However, recorded marks exceeding such a resolution limit can be reproduced, which is called a super-resolution phenomenon. Today, investigations into the cause of the super-resolution phenomenon and research and development on the super-resolution phenomenon are underway. Since the super-resolution phenomenon enables recording marks beyond the limit of resolving power to be reproduced, super-resolution information storage media can remarkably satisfy demands for high density and large storage capacity.

A necessary condition for the commercial application of a super-resolution information storage medium is that the information storage medium satisfies basic recording and reproduction characteristics as a storage medium. In particular, a super-resolution information storage medium utilizes a recording light beam and a reproducing light beam having relatively high power, compared with a conventional information storage medium. In addition, major problems of super-resolution information storage media are reproduction signal characteristics such as carrier-to-noise ratio (CNR), jitter, or RF signal, and realization of a stable reproduction signal. In order to realize a super-resolution information storage medium, a prerequisite for the super-resolution information storage medium is to satisfy reproduced signal characteristics.

Now, an area of a reproducing beam spot where a super-resolution phenomenon occurs on a super-resolution information recording medium will be described with reference to FIG. 1 .

As shown in FIG. 1, a mark 110 is recorded on a track 100 of a super-resolution information storage medium, and due to a difference in local light intensity, a temperature distribution or a change in optical characteristics occurs within a beam spot 120 falling on the super-resolution layer. Thus, marks 110 beyond the resolution limit can also be reproduced. In other words, the temperature distribution or the change of the optical properties takes place in a subregion of the beam spot 120 , while no change occurs at the peripheral region 140 of the subregion. As shown in FIG. 1, the partial region where the change occurs (hereinafter, will be referred to as a super-resolution region 130) may be a central portion. The regions in which the change in optical properties occurs may be continuous or alternating.

In fact, there are many reports that CNRs large enough to be applicable to practical media are obtained from marks of the same length with less than resolving power by super-resolution reproduction operations using various super-resolution materials. However, actual optical recording is not performed by recording marks with the same length at regular intervals, but by recording marks with the same length at irregular intervals (ie, the mark position detection method) or by recording marks with the same length at irregular intervals. Interval recording is performed with marks having different lengths (ie, mark length detection method). Specifically, in a CD or DVD, marks having various lengths in the range of 3T to 11T (here, T represents a clock frequency) are compositely recorded. However, none of the above-mentioned super-resolution techniques has been successful in reproducing such a composite signal, because the signal reflected from the optical recording medium contains not only the signal reflected from the region of the beam spot whose optical property is changed, but also all the signals from the changed optical property. The signal reflected from the peripheral area of the above area. If there is no signal from the peripheral region, the effective beam spot size is sufficiently reduced so that the composite signal can be reproduced. However, in the super-resolution technique described above, the difference between the region where the optical characteristics are changed and the peripheral region is used, and since the difference is small, the signal reflected from the peripheral region becomes an obstacle to reduction in the spot size. This causes ISI (Inter-Symbol Interference) which occurs when a series of marks are reproduced, so that a composite signal cannot be reproduced at high resolution.

FIG. 2A shows a recording pattern of a mark recorded on an information storage medium, and FIG. 2B shows an RF signal corresponding to a reproduced mark of the recording pattern shown in FIG. 2A. When the wavelength of the laser beam is 405nm, its NA is 0.85, and its resolving power is about 75nm, the recording pattern is based on a mark of about 75nm (less than the resolving power), a mark of about 300nm (greater than the resolving power) and between two marks combination of blanks. In the reproduced signal shown in Fig. 2B, when a 300nm-long mark or space appeared around the beam spot, the 75nm-long mark was affected by the 300nm-long mark and space, making it impossible to clearly detect the 75nm-long mark. Regions with 75 nm long labels are indicated by A, B, C, D, E and F. Referring to FIG. 2A and FIG. 2B, the levels of reproduced signals of areas A, B, C, D, E, and F differ according to the number of 75nm-long marks and spaces. In addition, the levels of reproduced signals of the areas A, B, C, D, E, and F are not constant, but may vary depending on the surrounding conditions of the 75 nm long mark.

invention disclosure

technical problem

The above-mentioned problem arises due to the ISI of the signal from the peripheral region 140 of the beam spot.

technical solution

According to an aspect of the present invention, there is provided a method and apparatus for accurately reproducing the recorded information by removing the reproduction signal from the peripheral area of the super-resolution area when the reproduction light beam is irradiated on the super-resolution information storage medium. data and prevent inter-symbol interference (ISI), in which changes in temperature distribution or optical properties occur in the super-resolution region.

Beneficial effect

According to the present invention, when a pre-pit or additional identification information other than user data is recorded, the time required for reproducing the pre-pit or the identification information by the preceding beam is the same as the time required for reproducing the pre-pit by the subsequent beam. The difference in the time required to pit or identify information can be used as the delay time.

In the data reproducing method of a super-resolution information storage medium according to an aspect of the present invention, as described above, when reproducing data recorded in the form of marks, signal components from peripheral areas other than the super-resolution area are removed, thereby improving A characteristic of a reproduction signal in which a temperature distribution or a change in optical characteristics occurs by irradiating a reproduction light beam having a relatively high power in the super-resolution region. In addition, a method of controlling the time delay is used to precisely control the distance between the light spots, resulting in a more accurate reproduced signal. These methods can improve the characteristics of signals obtained by reproducing data recorded in random patterns, thereby contributing to the improvement of the practicality of super-resolution information storage media.

In addition, the data reproducing device for a super-resolution information storage medium according to an aspect of the present invention can improve reproduced signal characteristics by simply processing the signal without greatly changing the existing reproducing device.

Using the data reproduction method and device according to one aspect of the present invention improves the data reproduction performance of super-resolution information storage media, thereby realizing the practical application of high-quality, high-density, high-capacity information storage media.

Description of drawings

Fig. 1 shows the region where the super-resolution phenomenon occurs at the reproducing beam spot irradiated on the super-resolution information storage medium;

2A shows a recording pattern in which marks having a size smaller than the resolving power of a reproducing light beam of super-resolution power and marks having a size larger than the resolving power are recorded;

FIG. 2B shows an RF signal obtained by reproducing information recorded in the recording pattern of FIG. 2A using a reproducing beam of super-resolution power;

3 is a cross-sectional view schematically showing an example of a super-resolution information storage medium to which a reproducing method according to an aspect of the present invention is applied;

4 shows a super-resolution power beam and a non-super-resolution power beam irradiated onto an information storage medium in a data reproduction method according to an embodiment of the present invention;

5A and 5B are enlarged views of beam areas of super-resolution power beams and non-super-resolution power beams irradiated onto an information storage medium in a data reproduction method according to an embodiment of the present invention;

6A shows a reproduced signal obtained by irradiating a super-resolution power beam to a mark recorded in the recording pattern shown in FIG. 2A according to a data reproducing method according to an aspect of the present invention;

6B shows a reproduced signal obtained by irradiating a non-super-resolution power beam into a mark recorded in the recording pattern shown in FIG. 2A according to a data reproducing method according to an aspect of the present invention;

Figure 6C shows a difference signal between the reproduced signals shown in Figure 6A and Figure 6B;

7A shows a reproduced signal obtained by irradiating a super-resolution power beam into randomly recorded marks according to a data reproducing method according to an aspect of the present invention;

7B shows a reproduction signal obtained by irradiating a non-super-resolution power beam into randomly recorded marks according to a data reproduction method according to an aspect of the present invention;

Figure 7C shows a difference signal between the reproduced signals shown in Figure 7A and Figure 7B;

Figure 8 shows an eye pattern obtained from the difference signal shown in Figure 7C;

Fig. 9A schematically shows a data reproducing device for a super-resolution information storage medium according to an embodiment of the present invention;

Figure 9B shows a blazed grating element according to an embodiment of the present invention;

Fig. 10 schematically shows a modification of the data reproduction device of Fig. 9A;

11 is a flowchart illustrating a data reproducing method according to an embodiment of the present invention;

12 is a graph showing a result obtained by simulating the jitter of the signal after subtraction according to the delay time;

Fig. 13 shows the calculation of the first delay time used in the reproduction method of Fig. 11;

FIG. 14 shows a modification of the recording/reproducing signal processor of the data reproducing apparatus of FIG. 9A or FIG. 10, and the modified signal utilizes a dither value to perform compensation;

15 is a flowchart illustrating a method of compensating for a time delay between a first light beam and a second light beam using a jitter value according to an embodiment of the present invention;

Fig. 16 shows a super-resolution information storage medium having a track in which pre-pit is generated in a predetermined area;

FIG. 17 is a flowchart illustrating a method of compensating for a time delay between a first beam and a second beam using pre-pit or identification information according to another embodiment of the present invention.

best way

According to an aspect of the present invention, there is provided a method of reproducing data recorded in a super-resolution information storage medium with marks having a size smaller than the resolving power of an incident light beam, the method comprising: The first light beam and the second light beam with resolution power that does not cause the super-resolution phenomenon are irradiated onto the information storage medium; the first reproduction signal based on the first light beam and the second reproduction signal based on the second light beam are detected; compensation and calculation of the first The time delay between the reproduced signal and the second reproduced signal.

According to another aspect of the present invention, the computing operation may include obtaining a difference signal between the first reproduced signal and the second reproduced signal. The first beam and the second beam may be irradiated onto the same track with a time delay.

According to another aspect of the present invention, the irradiating operation may include splitting a light beam emitted from a single light source into a first light beam and a second light beam by using a diffraction element. In the operation of dividing beams emitted from a single light source, a +k order diffracted beam among a plurality of diffracted beams generated by a diffraction element may be used as a first beam, and a -k order diffracted beam may be used as a second beam. Optionally, the -k order diffracted beam among the plurality of diffracted beams generated by the diffraction element may be used as the first beam, and the +k order diffracted beam may be used as the second beam. The diffractive element may be a blazed grating element.

According to another aspect of the present invention, the irradiating operation may include emitting the first light beam and the second light beam from independent light sources including the first light source and the second light source, respectively.

According to another aspect of the present invention, there is provided a method of reproducing data recorded in a super-resolution information storage medium in the form of marks having a size smaller than the resolving power of an incident light beam, the method comprising: The first light beam is irradiated into the information storage medium; a plurality of second light beams with non-super-resolution power are irradiated onto the information storage medium irradiated by the first light beams with a predetermined time delay; the first reproduced signal based on the first light beams and The second reproduced signal of the second light beam detects the final reproduced signal.

According to another aspect of the present invention, the detecting operation may include obtaining a difference signal between the first reproduced signal and the second reproduced signal.

According to another aspect of the present invention, the detecting operation may further include compensating for a time delay between the first reproduced signal and the second reproduced signal. Optionally, the detection operation may further include: compensating for a predetermined time delay to minimize jitter or bER of the final reproduced signal. Optionally, the detecting operation may further comprise: utilizing the time required to reproduce pre-pit or identification information not used as user data using the first beam and the time required to reproduce the pre-pits or identification information using the second beam time difference to compensate for the predetermined time delay. Optionally, the detection operation may further include: using a wobble signal to compensate for a predetermined time delay.

According to another aspect of the present invention, there is provided an apparatus for reproducing data recorded in a super-resolution information storage medium in the form of marks having a size smaller than the resolving power of an incident light beam, the apparatus comprising: an optical pickup, A first light beam having a resolving power causing a super-resolution phenomenon and a second light beam having a resolving power not causing a super-resolution phenomenon are irradiated onto an information storage medium; a signal processor detecting a first reproduced signal of the first light beam and the second light beam the second reproduced signal, compensates the time delay between the first reproduced signal and the second reproduced signal, and operates the first reproduced signal and the second reproduced signal; the controller controls the optical pickup using the signal received from the signal processor .

According to another aspect of the present invention, there is provided an apparatus for reproducing data recorded in a super-resolution information storage medium in the form of marks having a size smaller than the resolving power of an incident light beam, the apparatus comprising: an optical pickup, irradiating a first beam of resolving power into the information storage medium, and irradiating a plurality of second beams of non-super-resolution power onto the area on the information storage medium irradiated by the first beam; the signal processor, based on the first beam The first reproduced signal and the second reproduced signal of the second light beam detect a final reproduced signal; the controller controls the optical pickup using the signal received from the signal processor.

Detailed ways

Now, exemplary embodiments of the present invention will be described in detail, examples of which are shown in the accompanying drawings, in which like reference numerals refer to like parts throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

A data reproducing method according to an aspect of the present invention is applicable to a super-resolution information storage medium configured to reproduce information recorded in a recording mark having a size exceeding a resolution limit.

Before explaining the data reproducing method according to an aspect of the present invention in detail, an exemplary super-resolution information storage medium will be described first.

3, the super-resolution information storage medium includes a substrate 310 and a first dielectric layer 320, a recording layer 330, a second dielectric layer 340, a super-resolution reproducing layer 350, a third dielectric layer 360 and a covering layer formed sequentially on the substrate 310. Layer 370. Here, a light beam used in recording/reproducing information is focused on an objective lens (OL) and incident on the super-resolution information storage medium through the cover layer 370 .

The substrate 310 is preferably made of at least one material selected from the group consisting of polycarbonate, polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass, and preferably (but not Necessary) have a reflective film for reflecting incident light beams, the reflective film is coated on one surface of the substrate 310 , that is, the surface facing the first dielectric layer 320 .

The first to third dielectric layers 320, 340 and 360 control optical and/or thermal characteristics of the super-resolution information storage medium. The cover layer 370 covers layers including the recording layer 330 and the super-resolution reproducing layer 350 formed on the substrate 310 . Here, the first to third dielectric layers 320, 340, and 360 and the capping layer 370 are not essential components of the super-resolution information storage medium. Of course, even if these layers are not formed in the super-resolution information storage medium, information can be reproduced.

The first to third dielectric layers 320, 340, and 360 are preferably (but not necessarily) made of at least one material selected from the group consisting of oxides, nitrides, carbides, sulfides, and fluorides. . In other words, the first to third dielectric layers 320, 340 and 360 are preferably (but not necessarily) made of silicon oxide (SiO _x ), magnesium oxide (MgO _x ), aluminum oxide (AlO _x ), titanium oxide (TiO _x ), vanadium oxide (VO _x ), chromium oxide (CrO _x ), nickel oxide (NiO _x ), zirconium oxide (ZrO _x ), germanium oxide (GeO _x ), zinc oxide (ZnO _x ), silicon nitride (SiN _x ), aluminum nitride (AlN _x ), titanium nitride (TiN _x ), zirconium nitride (ZrN _x ), germanium nitride (GeN _x ), silicon carbide (SiC), zinc sulfide (ZnS), zinc sulfide- At least one material selected from the group consisting of a silicon oxide compound (ZnS—SiO) and magnesium fluoride (MgF ₂ ).

The recording layer 330 has a structure in which a recording mark (m) recorded by an incident light beam having a predetermined recording power level has a rectangular cross section or a cross section substantially the same as a rectangular shape. Here, the recording marks (m) include marks having a size not larger than the resolving power of an optical pickup for reproduction.

In order to reproduce data repeatedly using the super-resolution phenomenon, the chemical reaction temperature Tw of the recording layer 330 is higher than the temperature Tr at which the super-resolution phenomenon occurs in the super-resolution reproducing layer 350 .

Therefore, in order to generate the recording mark (m), the recording layer 330 must have a single-layer structure having a mixture of two or more materials having different physical chemically react with each other (eg, materials A and B in Figure 3).

For example, the recording layer 330 exists in the form of a thin film in which the materials A and B are mixed before data recording, that is, before a chemical reaction between the materials A and B. When a recording beam having a predetermined power level is irradiated onto the recording layer 330, a chemical reaction between the materials A and B occurs at the region where the beam spot of the recording layer 330 falls, and the state of the recording layer changes from that of the materials A and B to The mixture changes to compound A+B which has different physical properties than the mixture of materials A and B. Compound A+B generates recording marks (m) having reflectance different from recording marks in other regions.

Examples of the material A include tungsten (W), and examples of the material B include silicon (Si), based on the fact that, in the case of using Ge-Sb-Te as the material of the super-resolution reproduction layer, during reproduction, the super-resolution phenomenon Occurs at about 350°C, and recording must be performed at a recording temperature higher than the reproduction temperature. In other words, the W-Si alloy has a reaction temperature of about 600°C, which is not affected by the reproduction power.

When W and Si are selected, it is preferable (but not necessary) to form the recording layer 330 by mixing the two materials such that the ratio of the number of W atoms to the number of Si atoms is 1:2. In this case, the WSi ₂ compound is generated by a chemical reaction occurring at a predetermined region of the recording layer 330 irradiated with a light beam having recording power. The above-mentioned ratio of the numbers of W and Si atoms, ie, 1:2, is for illustration only, and the ratio is not limited thereto.

Although W and Si are described as materials of the recording layer, these two materials are for illustration only, and can be selected from materials capable of chemically reacting at a temperature higher than the reproducing temperature within the range in which recording can be performed with a laser beam. Choose any two or more materials from the group. For example, the recording layer may be composed of vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), germanium (Ge), niobium (Nb), molybdenum (Mo), silver ( At least two materials selected from the group consisting of Ag), tin (Sn), antimony (Sb), tellurium (Te), titanium (Ti), zirconium (Zr) and lanthanum-based elements.

The super-resolution reproduction layer 350 is a layer made of a phase-change material that undergoes changes in temperature distribution or optical characteristics at some regions of the incident beam spot. In other words, the super-resolution reproducing layer 350 is preferably (but not necessarily) formed of a chalcogenide (chalcogenide) phase-change material composed of sulfur (S), selenium (Se), tellurium (Te) At least one selected from the group consisting of. For example, the super-resolution reproduction layer 350 includes: selenium-sulfur (Se-S), selenium-tellurium (Se-Te), sulfur-tellurium (S-Te), phosphorus-sulfur (P-S), phosphorus-tellurium (P -Te), phosphorus-selenium (P-Se), arsenic-sulfur (As-S), arsenic-selenium (As-Se), arsenic-tellurium (As-Te), antimony-sulfur (Sb-S), antimony - Selenium (Sb-Se), Antimony-Tellurium (Sb-Te), Silicon-Sulfur (Si-S), Silicon-Selenium (Si-Se), Silicon-Tellurium (Si-Te), Germanium-Sulfur (Ge- S), germanium-selenium (Ge-Se), germanium-tellurium (Ge-Te), tin-sulfur (Sn-S), tin-selenium (Sn-Se), tin-tellurium (Sn-Te), silver- Sulfur (Ag-S), silver-selenium (Ag-Se), silver-tellurium (Ag-Te), aluminum-sulfur (Al-S), aluminum-selenium (Al-Se), aluminum-tellurium (Al-Te ), gallium-sulfur (Ga-S), gallium-selenium (Ga-Se), gallium-tellurium (Ga-Te), indium-sulfur (In-S), indium-selenium (In-Se), indium-tellurium at least one selected from the group consisting of (In—Te)-based compounds; and a compound comprising at least one selected from the group consisting of these elements.

Preferably (but not necessarily), the super-resolution reproduction layer 350 is made of a phase change material based on germanium-antimony-tellurium (Ge-Sb-Te) or silver-indium-antimony-tellurium (Ag-In-Sb-Te) become.

Therefore, the super-resolution reproducing layer 350 creates a super-resolution region at which changes in temperature distribution or optical characteristics occur in some regions of the beam spot due to phase change at a predetermined temperature, thereby being able to recover to have a value smaller than the resolution. The size of the capability is recorded in the form of a record mark (m).

As described above, a super-resolution region in which changes in temperature distribution or optical characteristics occur by reproducing the beam is created at some regions of the reproducing beam spot, which may exist in the center portion of the beam spot.

The information storage medium mentioned above is only an example to illustrate the super-resolution phenomenon. Rather, according to the reproducing method of one aspect of the present invention, any type of information storage medium subjected to the super-resolution phenomenon can be used.

Now, a data reproducing method of an information storage medium according to an embodiment of the present invention will be described.

In the data reproducing method of an information storage medium according to an aspect of the present invention, as shown in FIG. . A recording mark (m) is recorded along a track (T) of an information storage medium, and the first beam B1 and the second beam B2 are irradiated into different positions of the same track.

The first light beam B1 and the second light beam B2 may be generated by splitting a light beam emitted from a single light source using a beam splitter or by two light sources emitting light beams of different power levels. The beam splitter may be a grating element or a diffractive element such as a hologram.

The first beam B1 has reproduction power at which super-resolution occurs (referred to as super-resolution power), and the second beam B2 has reproduction power at which super-resolution does not occur (referred to as non-super-resolution power). The first beam B1 and the second beam B2 are irradiated simultaneously.

As shown in FIG. 5A, in the area irradiated by the first light beam B1, changes in temperature distribution or optical characteristics occur in some areas of the light spot, thereby forming a super-resolution area where a super-resolution phenomenon occurs. In the peripheral region of the super-resolution region, no super-resolution phenomenon occurs. As shown in FIG. 5B , no super-resolution phenomenon occurs at the area irradiated by the second light beam B2.

When the wavelength of the first light beam B1 is λ and its numerical aperture is NA1, the resolving power of the first light beam B1 is λ/(4×NA1). When a single light source is used to obtain the first beam B1 and the second beam B2, the wavelength of the second beam B2 is the same as that of the first beam B1, namely λ, and its numerical aperture is NA2, the resolving power of the second beam B2 is λ /(4×NA2). The numerical aperture of a beam is defined as a value obtained by dividing the radius of the beam by the focal length of the objective lens. An aspect of the invention is based on the idea that only the signal reflected from the super-resolved region of the spot can be extracted by subtracting the signal reflected from the peripheral region from the signal reflected from the entire region of the spot.

6A illustrates a first reproduced signal obtained by irradiating a super-resolution power beam into marks recorded in the recording pattern shown in FIG. 2A by the data reproducing method according to an aspect of the present invention. 6B illustrates a second reproduced signal obtained by irradiating a non-super-resolution power beam into a mark recorded in the recording pattern shown in FIG. 2A by the data reproducing method according to an aspect of the present invention. FIG. 6C shows a differential signal between the first reproduced signal and the second reproduced signal.

In other words, the first reproduced signal of FIG. 6A from which the marks recorded in the pattern of FIG. 2A are reproduced has a super-resolution phenomenon. The second reproduced signal of FIG. 6B , from which the marks recorded in the pattern of FIG. 2A are reproduced, has no super-resolution phenomenon.

The time delay of the first reproduced signal and the second reproduced signal is compensated and operated by the difference signal, thereby obtaining the difference signal between the first reproduced signal and the second reproduced signal shown in FIG. 6C. As a result, signal components reflected from the peripheral region of the beam spot are excluded from the difference signal, and only signal components from the super-resolved region remain in the difference signal, thereby overcoming the ISI problem caused by the peripheral region. Referring to Figure 6C, 75nm marks with a size smaller than the resolving power and spaces between them are accurately reproduced at parts A, B, C, D, E, and F, and regardless of the number of marks and spaces, A, B , C, D, E, and F sections have uniform signal levels. In addition, even when the 300nm mark and space appeared near the 75nm mark and space, the signal level of the 300nm mark adjacent to the 75nm mark coincided with the signal level of the other 300nm marks. Furthermore, for 300nm marks smaller than the full beam spot size, plateaus appear at high and low levels, implying a reduction in the size of the effective beam for reproduction compared to the actual spot size.

Meanwhile, although it has been described and shown that the difference signal between the first reproduction signal and the second reproduction signal is used in the exemplary embodiment, various arithmetic techniques may be used.

7A, 7B, and 7C illustrate results of reproducing data recorded in random recording patterns by the reproducing method according to an aspect of the present invention. 7A shows a first reproduced signal obtained by reproducing a randomly recorded mark with a first power beam according to a data reproducing method according to an aspect of the present invention, and FIG. 7B shows a data reproducing method according to an aspect of the present invention utilizing a second power beam. 7C shows a difference signal between the first and second reproduction signals shown in FIGS. 7A and 7B . Since the levels of the first reproduced signal and the second reproduced signal in FIGS. 7A and 7B are not constant, although the first reproduced signal and the second reproduced signal are clipped at a predetermined level, the recording marks cannot be reproduced correctly. . On the other hand, the difference signal of FIG. 7C has a constant level, so if the difference signal is clipped at a predetermined level, the recorded marks can be correctly reproduced.

FIG. 8 shows an eye pattern obtained from the difference signal shown in FIG. 7C, which shows good jitter characteristics of the reproduced signal. That is, the data reproducing method according to an aspect of the present invention can be effectively applied to data recorded in a random recording pattern in a super-resolution information storage medium.

In the data reproduction method according to an aspect of the present invention, a super-resolution power beam and a non-super-resolution power beam are irradiated with a predetermined time delay, and the first reproduced signal based on the super-resolution power beam and the second reproduction signal based on the non-super-resolution power Time delays between reproduced signals are compensated and calculated using optimal arithmetic techniques. In this way, ISI caused from the peripheral region of the super-resolution region in the reproduction beam spot can be resolved, thereby improving reproduction signal characteristics in a simple manner.

FIG. 9A schematically shows a data reproducing apparatus 900 that can perform a data reproducing method according to an aspect of the present invention.

The data reproducing apparatus 900 includes: an optical pickup 910 , a recording/reproducing signal processor 920 and a controller 930 . More specifically, the optical pickup 910 includes: a light source 911 for emitting light beams; a diffraction element 912 for diffracting the light beams emitted from the light source 911; collimation; a beam splitter 914 for converting the propagation path of the incident beam; and an objective lens 915 for focusing the beam passing through the beam splitter 914 onto the information storage medium 300 .

The light beam emitted from the light source is divided into a first light beam and a second light beam by the diffraction element 912 . The power of the first light beam and the power of the second light beam can be adjusted by changing the diffraction pattern of the diffraction element 912 . Diffractive element 912 may be a grating element or a hologram.

The first and second light beams reflected from the information storage medium are reflected by beam splitter 914 and received in photodetector 916 . The first and second light beams received in the photodetector 916 are converted into electrical signals by the recording/reproducing signal processor 920 and output as reproduction signals.

The recording/reproducing signal processor 920 causes the amplifier 921 to amplify the first beam signal photoelectrically converted by the photodetector 916 and the compensator 922 to compensate the time delay of the second beam signal photoelectrically converted by the photodetector 916 . The reproduced signal of the first beam and the reproduced signal of the second beam are converted by the operation unit 923, and then output as a radio frequency (RF) signal through channel 1 (Ch1) and as a push-pull signal through channel 2 (Ch2).

In order to reproduce a recording mark having a size smaller than the resolution capability, the controller 930 controls the optical pickup 910 to emit a super-resolution power beam or a non-super-resolution power beam according to the material properties of the information storage medium 300 . In addition, the controller 930 performs focus servo and tracking servo using RF signals and push-pull signals.

Now, the diffractive element 912 will be described in more detail. The first light beam with super-resolved power and the second light beam with non-super-resolved power must satisfy the aberration amount condition in addition to the power condition. In other words, the aberration amounts of the first and second light beams should be substantially the same. When the aberration amounts of the first and second light beams are different, the shape of the light spot formed by the first light beam on the information storage medium is different from the shape of the light spot formed by the second light beam on the information storage medium. The different spot shapes formed by the first and second light beams make it difficult, but not impossible, to implement aspects of the invention.

In order to satisfy the power conditions and aberration conditions of the first light beam and the second light beam, in the embodiment of the present invention, a blazed grating element is used in the diffraction element 912 .

Fig. 9B shows a blazed grating element according to an embodiment of the invention. When the light beam 951 emitted from the light source 911 is incident on the blazed grating element 912 of FIG. order diffracted beam 954, and ±2-order to ±N-order diffracted beams (not shown). Here, N represents a theoretical infinite integer.

The aberration amounts of the +1st-order diffracted beam 953 and the −1st-order diffracted beam 954 are substantially the same. Those of ordinary skill in the technical field of the present invention can easily realize the blazed grating element 912, so that the +1 order diffracted beam 953 has high power, and the −1 order diffracted beam 954 has relatively lower power than the +1 order diffracted beam 953, Alternatively, the +1st order diffracted beam 953 has low power, and the −1st order diffracted beam 954 has relatively higher power than the +1st order diffracted beam 953 . Meanwhile, the power of the 0th order diffracted beam 952 is too weak, so it can be ignored.

Although the data reproducing device 900 shown in FIG. 9A includes a diffraction element to generate the first light beam and the second light beam, as shown in FIG. That is, a first light source 941a for a first light beam) and a second light source 941b for emitting a non-super-resolved power light beam (ie, a second light beam). In FIG. 10, the first light source 941a and the second light source 941b are packaged as an optical module. Optionally, in addition to forming the optical module, the first light source and the second light source may be independently provided and arranged at different positions. When the first light source and the second light source are independently provided in this manner, it is not necessary to additionally provide a diffraction element for generating the first light beam and the second light beam.

In FIG. 10, the same functional elements are denoted by the same reference numerals as those in FIG. 9, and no detailed explanation will be given.

Meanwhile, the photodetector 942 includes: a first photodetector 942a for receiving the first light beam emitted from the first light source 941a and reflected from the information storage medium 300; and a second photodetector 942b for receiving the light beam from the second The second light beam emitted from the light source 941 a and reflected from the information storage medium 300 . The time delay between the first reproduced signal based on the first beam and the second reproduced signal based on the second beam is compensated by the compensator 922 and converted by the arithmetic unit 923, thereby producing a signal having excellent signal characteristics and no ISI RF signal.

As described above, when the first light source and the second light source are provided independently, the first light source or the second light source can be preferably used as the light source for data recording. Also, the first light source and the second light source may be configured such that the optical pickup is compatible for information storage media having different formats.

So far, the embodiment of the present invention has been described in which two light beams, a first light beam with super-resolved power and a second light beam with non-super-resolved power, are irradiated onto a super-resolved information storage medium. However, in another embodiment of the present invention, a plurality of light beams with non-super-resolved power may be generated by a diffraction element or a plurality of light sources, and the plurality of light beams with non-super-resolved power are combined with the light beams with super-resolved power The light beams are irradiated together onto the super-resolution information storage medium to reproduce data therefrom. In other words, after the plurality of light beams with non-super-resolution power and the light beam with super-resolution power are irradiated onto the super-resolution information storage medium, the reproduction signals obtained from all the light beams with non-super-resolution power can be used to obtain the final reproduction signal, as shown in Equation 1:

Final RF signal = RF ₁ -(g ₁ RF ₂ +g ₂ RF ₃ +...+g _N-1 RF _N ) ...(1)

Here, RF ₁ represents a reproduced signal obtained from a beam having super-resolution power, RF ₂ to RF _N represent reproduced signals obtained from a (N-1) beam, and g ₁ to g _N-1 are predetermined coefficients. The reproduced signals _RF2 to _RFN and _RF1 have a time delay. The final RF signal shown in Equation 1 can be obtained by one of ordinary skill in the art to which this invention pertains.

FIG. 11 is a flowchart illustrating a data reproducing method performed by the data reproducing apparatus of FIG. 9A or 10. Referring to FIG. Referring to FIG. 11 , first, in operation 1100 , the optical pickup 910 or 940 irradiates a first light beam having super-resolution power onto the information storage medium 300 .

Next, in operation 1110, the optical pickup 910 or 940 irradiates the second beam having non-super-resolution power onto the area of the information storage medium 300 irradiated by the first beam with a predetermined time delay. The irradiation of the second beam with a predetermined time delay does not mean that the optical pickup 910 intentionally delays the irradiation of the second beam, but means that the time delay is caused by the first beam first passing along the track and the second beam following the first beam. Generated naturally by traversing along the same track.

In operation 1120, the recording/reproducing signal processor 920 compensates for the difference between the first reproduction signal of the first light beam irradiated on and reflected by the information storage medium 300 and the second reproduction signal of the second light beam irradiated on the information storage medium 300. time delay between them, and perform operations such as subtracting the second reproduced signal from the first reproduced information to output the final reproduced signal.

When super-resolution reproduction can be achieved at high power, and the second reproduced signal is subtracted from the first reproduced signal, if the time delay between the first reproduced signal and the second reproduced signal is not accurately taken into account, then from the subtraction The characteristics of the signal are degraded. More specifically, a first reproduction signal is obtained from spot 1 capable of super-resolution reproduction at high power, and a second reproduction signal is obtained from spot 2 capable of general reproduction at low power. Then, the subtraction is performed by the amplifier 921 of FIG. 9A or FIG. 10 by giving an appropriate gain to the second reproduced signal. At this time, the delay unit 922 controls a time delay between the first reproduction signal and the second reproduction signal caused by the spatial distance between the light spots 1 and 2 . If the time delay between the first reproduced signal and the second reproduced signal is inaccurate, the signal resulting from the subtraction has poor characteristics. Of course, said time delay can be obtained from the spatial distance between spots 1 and 2, but during disc reproduction various external disturbances may occur. For example, if the rotational speed of the spindle motor changes slightly, or if a radial or tangential tilt occurs, the actual spatial distance between spots on the disc may change. If the change in the spatial distance between the light spots is not adequately adjusted, the final reproduced signal has poor quality.

FIG. 12 is a graph showing the results obtained by simulating the jitter of the signal subtracted according to the delay time. In the simulation of Fig. 12, the linear velocity of the light spot is 5 m/s. When the jitter is 10%, a margin of ±0.04T is obtained. Since the margin of ±0.04T corresponds to ±0.03nsec, the delay time margin of ±0.04T is very narrow, so a unit capable of precisely controlling the delay time is required.

The time delay between the first reproduced signal and the second reproduced signal can be accurately controlled by the following methods: first, using jitter or bER; second, using pre-pit or predetermined identification information; Three, use swing signals. In the method using the wobble signal, discontinuous points of the wobble signal may be used.

First, a method of accurately controlling a time delay between a first reproduction signal and a second reproduction signal using dither or bER will be described. In this method, the jitter or bER of the final reproduced signal obtained based on the first reproduced signal and the second reproduced signal is monitored, and the time delay between the first reproduced signal and the second reproduced signal is compensated so that the monitored jitter or bER minimum.

FIG. 14 shows a signal processor 1420 which is a modification of the recording/reproducing signal processor 920 of the data reproducing apparatus 900 of FIG. 9A or FIG. . Referring to FIG. 14, the light of the first beam reflected from the information storage medium 300 is detected by the first photodetector 942a, and the light of the second beam reflected from the information storage medium 300 is detected by the second photodetector 942b.

The delay unit 1421 of the signal processor 1420 receives the light output by the first photodetector 942a, and delays the received light by a first delay time to compensate for the light spot 1 from the first photodetector 942a and the light spot 1 from the second photodetector 942a. The time delay between the light spots 2 of 942b, and the delayed light is provided to the arithmetic unit 1423. The amplifier 1422 of the signal processor 1420 receives the light output by the second photodetector 942b, amplifies the received light, and provides the amplified light to the operation unit 1423. The arithmetic unit 1423 subtracts the second reproduced signal from the first reproduced signal.

As shown in FIG. 13, by dividing the distance (d) between the first spot B1 formed by the first beam and the second spot B2 formed by the second beam by the linear velocity (v) of the first spot to obtain the first delay time (t). The delay unit 1421 may preliminarily compensate for a time delay between the first light spot and the second light spot by delaying the first reproduced signal for a first delay time.

In the embodiment of FIG. 14 , the delay unit 1421 uses the dither value to compensate the time delay between the first light spot and the second light spot twice. More specifically, the jitter compensation unit 1424 monitors the jitter or bER of the final reproduced signal output from the arithmetic unit 1423, and calculates a compensation value that minimizes the jitter or bER by adding the compensation value to the first delay time or from the first delay time The second delay time is obtained by subtracting the compensation value, and the second delay time is provided to the delay unit 1421 . Then, the delay unit 1421 delays the first reproduced signal for a second delay time, thereby precisely adjusting the time delay between the first light spot and the second light spot.

FIG. 15 is a flowchart illustrating a method of compensating for a time delay between a first reproduction signal and a second reproduction signal using a dither value according to an embodiment of the present invention. Referring to FIG. 15, in operation 1500, a first delay time is calculated from a distance between centers of first and second light spots and a linear velocity of the light spots.

Next, in operation 1510, a reproduced signal is obtained by delaying the detection signal of the spot 1 for a first delay time and performing an operation of the delayed detection signal and the detection signal of the spot 2 .

In operation 1520, jitter or bER of the reproduced signal is obtained, and a second delay time capable of minimizing the jitter or bER of the reproduced signal is calculated.

In operation 1530, a reproduced signal is obtained by delaying the detection signal of the spot 1 for a second delay time and performing an operation of the delayed detection signal and the detection signal of the spot 2 .

Now, a method of accurately compensating for a time delay between a first reproduced signal and a second reproduced signal using a pre-pit or predetermined identification information will be described with reference to FIGS. 16 and 17 . The predetermined identification information represents additional information periodically recorded to easily distinguish additional data from user data.

First, the pre-pits are briefly described with reference to FIG. 16 . Fig. 16 shows a super-resolution information storage medium having a track in which pre-pit is generated in a predetermined area.

An optical recording medium such as a DVD-RAM includes a header area in which header information is stored and a user data area in which user data is recorded. In DVD-RAM, each sector stores 128 bytes of header information, which is recorded as pre-pit when the disc substrate is manufactured. The pickup can recognize the sector number, sector type, land track/groove track, etc. from header information recorded in the header area composed of pre-pit. In addition, the pickup can perform servo control using header information. In other words, a header area formed with uneven pre-pits is provided in a predetermined area of each sector. A pickup included in the recording/reproducing apparatus can easily access a desired position on the disc using the information recorded in the header area.

Referring to FIG. 16, land tracks and groove tracks corresponding to a user data area in which user data is recorded are formed on a super-resolution information storage medium to which an aspect of the present invention is applied. A header area 1600 in which header information is recorded as a pre-pit is also formed on the super-resolution information storage medium.

As described above, in order to store header information, a header area formed of pre-pits may be formed even on a predetermined area of a super-resolution information storage medium, as shown in FIG. 16 .

FIG. 17 is a flowchart illustrating a method of compensating for a time delay between a first reproduced signal and a second reproduced signal using pre-pit and identification information according to another embodiment of the present invention.

First, in operation 1700, a first delay time is calculated from a distance between centers of first and second light spots and a linear velocity of the light spots.

Next, in operation 1710, a reproduced signal is obtained by delaying the detection signal of the spot 1 for a first delay time and performing an operation of the delayed detection signal and the detection signal of the spot 2 .

Then, in operation 1720, the difference between the first beam and the second beam is compensated by using the time difference between the time required to reproduce the pre-pit or the identification information using the first beam and the time required to reproduce the pre-pit or the identification information using the second beam. time delay between.

Thereafter, in operation 1730, a reproduced signal is obtained by delaying the detection signal of the spot 1 by a time corresponding to the compensated time delay and performing an operation of the delayed detection signal and the detection signal of the spot 2 .

Although the super-resolution information storage medium to which the reproducing method according to an aspect of the present invention is applied is described as having a multilayer structure of 5 or 7 layers formed on a substrate, and the super-resolution layer is made of a specific material, the description The examples should be considered in all respects as illustrative. Rather, aspects of the present invention are applicable to various types of information storage media that are subjected to the super-resolution phenomenon.

While the invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various modifications may be made without departing from the scope and spirit of the invention as defined by the claims. Changes in form and detail.

Industrial availability

The present invention is applicable to a method and apparatus for reproducing data recorded on a super-resolution information storage medium and the super-resolution information storage medium.

Claims (22)

1. A method of reproducing data recorded in a super-resolution information storage medium with a mark having a size smaller than the resolving power of an incident light beam, the method comprising: irradiating the information storage medium with a first light beam having a resolving power causing a super-resolution phenomenon and a second light beam having a resolving power not causing a super-resolution phenomenon; detecting a first reproduced signal based on the first beam and a second reproduced signal based on the second beam; compensating for a time delay between the first reproduced signal and the second reproduced signal; calculating a difference signal between the first reproduced signal and the second reproduced signal, Wherein, the step of irradiating the first and second light beams includes: using a diffraction element to divide the light beam emitted from a single light source into a first light beam and a second light beam, Wherein, in the step of dividing the beam emitted from a single light source, the -k order diffracted beam among the plurality of diffractive beams generated by the diffraction element is used as the first beam, and the +k order diffracted beam is used as the second beam, Wherein, the k represents an infinite integer, and the diffraction element is a blazed grating element. 2. The data reproducing method according to claim 1, wherein signal components reflected from peripheral regions of the first light beam and the second light beam are excluded from the difference signal. 3. The data reproducing method according to claim 1, wherein only signal separation from the super-resolution region remains in the difference signal. 4. The data reproducing method as claimed in claim 1, wherein the aberration amounts of the first light beam and the second light beam are substantially the same. 5. The data reproducing method as claimed in claim 1, wherein the first light beam and the second light beam are irradiated onto the same track with a time delay. 6. A method of reproducing data recorded in a super-resolution information storage medium with a mark having a size smaller than the resolving power of an incident light beam, the method comprising: irradiating the information storage medium with a first light beam having a resolving power causing a super-resolution phenomenon and a second light beam having a resolving power not causing a super-resolution phenomenon; detecting a first reproduced signal based on the first beam and a second reproduced signal based on the second beam; compensating for a time delay between the first reproduced signal and the second reproduced signal; calculating a difference signal between the first reproduced signal and the second reproduced signal, Wherein, the step of irradiating the first and second light beams includes: using a diffraction element to divide the light beam emitted from a single light source into a first light beam and a second light beam, Wherein, in the step of dividing the light beam emitted from a single light source, the +k-order diffracted beam among the plurality of diffracted beams generated by the diffraction element is used as the first beam, and the -k-order diffracted beam is used as the second beam, Wherein, the k represents an infinite integer, and the diffraction element is a blazed grating element. 7. The data reproducing method according to claim 6, wherein signal components reflected from peripheral regions of the first light beam and the second light beam are excluded from the difference signal. 8. The data reproducing method as claimed in claim 6, wherein only signal separation from the super-resolution region remains in the difference signal. 9. The data reproducing method as claimed in claim 6, wherein the aberration amounts of the first light beam and the second light beam are substantially the same. 10. The data reproducing method as claimed in claim 6, wherein the first light beam and the second light beam are irradiated onto the same track with a time delay. 11. A method of reproducing data recorded in a super-resolution information storage medium with a mark having a size smaller than the resolving power of an incident light beam, the method comprising: irradiating a first light beam with super-resolution power into the information storage medium; irradiating a plurality of second beams of non-super-resolved power onto the information storage medium illuminated by the first beams; compensating for a time delay between the first reproduced signal from the first light beam and the second reproduced signal from the plurality of second light beams; performing a difference operation on the first reproduced signal and the second reproduced signal, wherein a light beam emitted from a single light source is divided into the first light beam and the plurality of second light beams by a diffraction element to detect a final reproduced signal by diffractive One of the +k-order diffracted beams in the plurality of diffracted beams generated by the element is used as the first beam, and a plurality of the -k-order diffracted beams are used as the plurality of second beams, Wherein, the k represents an infinite integer, and the diffraction element is a blazed grating element. 12. The data reproducing method as claimed in claim 11, wherein, in the step of compensating for the time delay, the time delay is compensated so that a jitter or a bit error rate of a final reproduced signal is minimized. 13. The data reproducing method as claimed in claim 11, wherein, in the step of compensating for the time delay, the time required to reproduce the pre-pit or identification information not used as user data by using the first light beam is different from that by using the second light beam. The time delay is compensated for by the difference in the time required to reproduce the pre-pit or identification information. 14. The data reproducing method as claimed in claim 11, wherein, in the step of compensating for the time delay, the time delay is compensated using a wobble signal. 15. An apparatus for reproducing data recorded in a super-resolution information storage medium with a mark having a size smaller than the resolving power of an incident light beam, the apparatus comprising: an optical pickup for irradiating the information storage medium with a first light beam having a resolving power causing a super-resolution phenomenon and a second light beam having a resolving power not causing a super-resolution phenomenon; a signal processor detecting a first reproduced signal based on the first light beam and a second reproduced signal based on the second light beam, compensating for a time delay between the first reproduced signal and the second reproduced signal, and analyzing the first reproduced signal and the second reproduced signal performing a difference operation on the reproduced signal; a controller to control the optical pickup using a signal received from the signal processor, Wherein, the optical pickup includes: a light source; and a diffraction element, which divides the light beam emitted from the light source into a first light beam and a second light beam, Wherein, the first beam corresponds to the +k-order diffracted beam in the plurality of diffracted beams generated by the diffraction element, and the second beam corresponds to the-k-order diffracted beam, Wherein, the k represents an infinite integer, and the diffraction element is a blazed grating element. 16. The data reproducing apparatus as claimed in claim 15, wherein the first light beam and the second light beam are irradiated onto the same track with a time delay. 17. An apparatus for reproducing data recorded in a super-resolution information storage medium with a mark having a size smaller than the resolving power of an incident light beam, the apparatus comprising: an optical pickup for irradiating the information storage medium with a first light beam having a resolving power causing a super-resolution phenomenon and a second light beam having a resolving power not causing a super-resolution phenomenon; a signal processor detecting a first reproduced signal based on the first light beam and a second reproduced signal based on the second light beam, compensating for a time delay between the first reproduced signal and the second reproduced signal, and analyzing the first reproduced signal and the second reproduced signal performing a difference operation on the reproduced signal; a controller to control the optical pickup using a signal received from the signal processor, Wherein, the optical pickup includes: a light source; and a diffraction element, which divides the light beam emitted from the light source into a first light beam and a second light beam, Wherein, the first beam corresponds to the -k order diffracted beam in the plurality of diffracted beams generated by the diffraction element, and the second beam corresponds to the +k order diffracted beam, Wherein, the k represents an infinite integer, and the diffraction element is a blazed grating element. 18. The data reproducing apparatus as claimed in claim 17, wherein the first light beam and the second light beam are irradiated onto the same track with a time delay. 19. An apparatus for reproducing data recorded in a super-resolution information storage medium with a mark having a size smaller than the resolving power of an incident light beam, the apparatus comprising: an optical pickup for irradiating a first light beam with super-resolution power into the information storage medium, and irradiating a plurality of second light beams with non-super-resolution power onto the information storage medium irradiated by the first light beam; a signal processor compensating for a time delay between the first reproduced signal from the first light beam and the second reproduced signal from the plurality of second light beams, and performing a difference operation on the first reproduced signal and the second reproduced signal to detect a final reproduce the signal; a controller to control the optical pickup using a signal received from the signal processor, Wherein, the optical pickup includes: a light source; a diffraction element, which divides the light beam emitted from the light source into a first light beam and the plurality of second light beams, Wherein, one of the -k order diffracted beams in the plurality of diffractive beams generated by the diffraction element is used as the first beam, and a plurality of beams in the +k order diffracted beams are used as the plurality of second beams, Wherein, the k represents an infinite integer, and the diffraction element is a blazed grating element. 20. The data reproducing apparatus as claimed in claim 19, wherein the signal processor compensates the time delay to minimize jitter or a bit error rate of a final reproduced signal. 21. The data reproducing apparatus as claimed in claim 19, wherein said signal processor utilizes the time required to reproduce pre-pits or identification information which are not used as user data using the first beam and the time required to reproduce the pre-pit or identification information using the second beam The difference in the time required to pre-pit or identify information is used to compensate for the time delay. 22. The data reproducing apparatus of claim 19, wherein the signal processor compensates for the time delay using the wobble signal.

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