KR100574822B1 - Optical Recording Media and Data Recording/Reproducing Apparatus and Method - Google Patents

Abstract

The present invention relates to an optical recording medium in which various kinds of information such as image information are optically recorded.

The optical recording medium of the present invention has a pit array formed alternately in a predetermined track unit as two or more different track pitches.

With this configuration, the optical recording medium according to the present invention can minimize the crosstalk between tracks because the optical pitch of the tracks can be different from each other and the adjacent track signals can be excluded by the light spot irradiated toward the wide track pitch. It becomes possible.

Description

Optical Recording Media and Data Recording / Reproducing Apparatus and Method

The present invention relates to an optical recording medium in which various kinds of information such as image information are optically recorded. The present invention also relates to an optical recording medium reproducing apparatus for optically accessing an optical recording medium to reproduce information.

In optical recording media such as CD and DVD, which have already been generalized as a recording medium using light, laser light is irradiated onto the recording layer to record or reproduce data. Such optical recording media are classified into read-only and rewritable media. In the former type, there are ROM types such as CD-ROM and DVD-ROM. In the latter type, the write once read many (WORM) type and the rewritable type are used depending on the number of rewritable times. , RAM type, etc. Usually, pits are formed on the information recording surface of the optical disc, which are represented by binary information. The reproducing apparatus of the optical disc reproduces the information by reading out the pits and decoding them. The optical disk 10 is formed with pits 10a having irregularities as shown in FIG. 1. The pit 10a is formed in an uneven shape corresponding to binary information along a spiral or concentric track reference line (k-1, k, k + 1) on an optical disk substrate made of a material such as polycarbonate. Is formed. The track pitch Tp (Track pitch) is equally spaced over the entire information recording surface area. On the other hand, a metal thin film (for example, Al) having a high reflectance is formed on the recording surface of the substrate on which the pit pattern is formed, and a protective film is formed on the metal thin film. The information recorded on the optical disc having such a track structure is reproduced by detecting the amount of light reflected by irradiating a light beam onto the track to be reproduced. The light spot of the light beam follows the track reference lines k-1, k, k + 1 to read information. At this time, the center of the light spot 1 is tracked to follow the track reference lines k-1, k, k + 1. Here, the reflected light reflected from the mirror area 10b where the pit 10a is not formed is detected as "light", while the reflected light reflected from the pit 10a is detected as dark. That is, the light beam irradiated to the mirror region 10b is almost totally reflected by the mirror region 10b, and the reflected light amount is large, whereas the light beam irradiated to the pit 10a is diffusely reflected at the pit 10a and the reflectance is reduced. The reflected light beams detected as "light" and "dark" are reproduced by being converted into an electrical signal and decoded by a photodetector. This reproducing method is adopted in the reproducible and rewritable optical recording media.

In recent years, optical recording media have tended to reduce the pit size and track pitch in order to increase the recording density, and to shorten the light source and increase the numerical aperture (NA). However, when the track pitch is reduced in the trend of densification, there is a problem that crosstalk occurs between adjacent tracks, thereby degrading reliability during playback. Due to this problem, there is a limit to reducing the track pitch, which is a major obstacle to improving the recording density.

Accordingly, it is an object of the present invention to provide an optical recording medium for minimizing crosstalk between tracks.

Another object of the present invention is to provide an optical recording medium having a high density recording capacity.

In order to achieve the above objects, the optical recording medium of the present invention is characterized by having two or more different track pitches having pit rows alternately formed in a predetermined track unit.

The optical recording medium of the present invention is characterized in that pit rows are formed with different first track pitches and second track pitches so as to have different intervals between adjacent tracks.

The optical recording medium of the present invention is characterized in that pit rows are formed by different first track pitches and second track pitches, and pit rows formed on tracks adjacent to the first track pitches are in contact with each other.

An apparatus for reproducing data of an optical recording medium of the present invention includes an optical pickup for reproducing pit-shaped data recorded on an optical recording medium, a signal detector for detecting a signal reproduced from the optical pickup, and a reproducing of the pit-shaped data. And a servo control unit for controlling the optical pickup, wherein the pit-shaped data recorded on the optical recording medium is formed of a pit row formed in a predetermined track unit as two or more different track pitches. The servo controller may control the optical pickup to accurately detect the pit rows formed with the different track pitches.

A data reproducing method of an optical recording medium of the present invention includes reproducing pit-shaped data recorded on an optical recording medium, and detecting the reproduced signal and outputting a reproduced signal. The pit-shaped data recorded in the pit shape data is formed of a pit row formed in a predetermined track unit as two or more different track pitches, and the pit shape data is controlled to accurately detect the pit rows formed with the different track pitches.

The data recording method of the optical recording medium of the present invention comprises the step of recording the data to be recorded on the optical recording medium as pit-shaped data, wherein the pit-shaped data recorded on the optical recording medium are two or more different from each other. A track pitch is formed of a pit row formed in a predetermined track unit, and the pit rows formed by the different track pitches are controlled to be recorded.

Other objects and advantages of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2 and 3.

FIG. 2 shows a layout of a track structure of an optical recording medium according to an embodiment of the present invention, wherein the optical disc 20 of the present invention shown in FIG. 2 has a first and second track pitch of different intervals. Pits 20a are formed on track reference lines (k-2, k-1, k, k + 1, k + 2 ...) forming (Tp1, Tp2). The track pitch relationship of adjacent tracks is set such that the first track pitch Tp1 is smaller than the second track pitch Tp2 (Tp1 < Tp2). Here, the first track pitch Tp1 is equal to or more than the pit width Wp (Tp1 ≧ Wp) to minimize crosstalk between the tracks, and less than 1.5 times the pit width Wp so that the track density is high (Tp1 <). 1.5 Wp) is preferable. In the light spot 11, the center of the light spot does not follow the track reference line (... k-2, k-1, k, k + 1, k + 2 ...) but the second track pitch Tp2. The information is read by following the optical spot center moving line (... Bk-2, Bk-1, Bk, Bk + 1, Bk + 2 ...) shifted toward the bulk track 22 having a track width of. . That is, in contrast to the conventional method, conventionally, the light spot 11 follows the track reference line to read information, but in the present invention, the center of the light spot 11 is the track reference line (k-2, k-1, Optical spot center shift line (... Bk-2, Bk-1, Bk, Bk shifted from k, k + 1, k + 2 ...) to bulk track 22 by 1/2 track width (Wp) +1, Bk + 2 ...) to read the information. Therefore, the track reference line (... k-2, k-1, k, k + 1, k + 2 ...) and the light spot center moving line (... Bk-2, Bk-1, Bk, Bk + 1, Bk + 2 ...) has a distance difference Δt between the track center corresponding to the 1/2 track width Wp and the light spot tracking center. The distance difference Δt between the track center and the light spot tracking center in terms of the light spot 11 is approximately 1/4 of the diameter of the light spot 11 (D / 4). Here, the diameter D of the light spot 11 is condensed from the objective lens so as to be larger than the first track pitch Tp1 and less than or equal to the second track pitch Tp2 (Tp1 &lt; D? Tp2). The principle of information detection is as follows. The light spot 11 follows the light spot center moving line (... Bk-2, Bk-1, Bk, Bk + 1, Bk + 2 ...) and the mirror area 10b in which the pit 20a is not formed. ) Reflected light reflected by the light is detected as "name" and reflected light reflected by the pit 20a is detected as "dark". At this time, the optical spot is shifted alternately by the first track pitch Tp1 and the second track pitch Tp2 every one track period, so that the optical spot center moving line (Bk-2, Bk-1, Bk, Bk) +1, Bk + 2 ...). The reflected light beams detected as "light" and "dark" are converted into electrical signals by a photodetector and reproduced by signal processing.

In the track structure of such an optical disc, the pits 20a are formed to minimize the first track pitch Tp1 so that the sides facing the pits 20a adjacent to the center of the first track pitch Tp1 are in contact with each other. When the second track pitch Tp2 is equal to or larger than the diameter D of the light spot, the number of tracks increases as the first track pitch Tp1 decreases, thereby realizing high density of information. The second track pitch Tp2 may be wider than the conventional track pitch. Therefore, the light beam is tracked toward the bulk track 22 (i.e., along the light spot center moving line) to detect information, thereby preventing crosstalk between tracks between adjacent tracks. For example, referring to the drawings, when reproducing information recorded on the kth track reference line k, the light spots 11 collected from the objective lens are shifted in the inner circumferential direction by Δt from the track reference line k. Information is detected along the light spot center moving line Bk on the bulk track 22 side. The inner circumferential side semicircle of this light spot 11 is condensed on the bulk track 22, and the outer circumferential side semicircle detects the information recorded in the k-th track k. Therefore, the light spot 11 focused on the k-th track k has the pits 20a formed on the k-1 th track k-1 adjacent to the inner circumferential side and the k + 1 th track k + 1 adjacent to the outer circumferential side. Only the pits 20a formed on the kth track k are read without being affected by the pits 20a formed on the. The light spot 11, which is shifted by the first track pitch Tp1 and reproduces the information recorded on the k + 1th track k + 1, is shifted in the circumferential direction by Δt from the center of the track so that the bulk track ( Information is detected along the light spot center moving line Bk + 1 on the side 22). The inner semicircle of the light spot 11 reads out the information recorded on the k + 1th track k + 1, and the outer semicircle is condensed on the bulk track 22. Therefore, the light spots 11 condensed on the k + 1th track k are connected to the pits 20a formed on the kth track k adjacent to the inner circumferential side and to the k + 2th track k + 2 adjacent to the outer circumferential side. Only the pits 20a formed on the k + 1 th track k + 1 are read out without being influenced by the formed pits 20a at all. Such an optical recording medium according to the present invention can be applied to both a concentric track structure or a spiral track structure in a reproduction-only type and a rewritable type, so that the recording density can be high.

3 is a block diagram schematically showing an apparatus for reproducing an optical recording medium according to an embodiment of the present invention.

In the configuration of FIG. 3, the apparatus for reproducing an optical recording medium according to the present invention includes an optical pickup 24 for irradiating a light beam to the optical disc 20 to convert the reflected light beam into an electrical signal, and a conversion from the optical pickup 24. A signal detection unit 28 for detecting the high frequency signal RF and the tracking error signal Te from the signal, a reproduction signal processing unit 30 for extracting the reproduction signal by signal processing the high frequency signal 30, and a tracking error. And a tracking servo unit 26 for controlling the light beam to follow the light spot center moving line (Bk-2, Bk-1, Bk, Bk + 1, Bk + 2 ...) according to the signal Te. do. The optical disc 20 shown in FIG. 3 has a track structure formed with different track pitches as shown in FIG. The optical pickup 24 focuses the light beam generated from the light source LD on the information recording surface of the optical disc 20 using the objective lens OL. As shown in FIG. 2, the light beam is focused in the form of a three beam by the main beam 11 and the auxiliary beams 12. The main beam 11 is focused on the destination track to be reproduced and the auxiliary beams 12 are focused on both tracks adjacent to the destination track to detect the tracking error signal. In Fig. 2, if the target track to be reproduced is a track along the k + 2th track reference line k + 2, the main beam 11 is a light spot shifted by Δt from the k + 2nd track reference line k + 2 to the inner circumferential side. The center of the effective diameter is followed by the center moving line Bk + 2 to read information. The center of the effective diameter is followed by the k + 1th track reference line k + 1 adjacent to the inner circumferential side of the first auxiliary beam 12 and the second auxiliary beam 12 is the target track (k + 2). The center of the effective diameter follows the k + 3th track k + 1 adjacent to the outer peripheral side at k + 2). To this end, the optical pickup 24 uses a three-beam optical pickup. The main beam 11 and the subsidiary beam 12 are focused on the photodetector PD by traveling back the optical path in the target track and the adjacent track, respectively. The photodetector PD is configured to detect the quadrant photodetectors PDa, PDb, PDc, PDd and the auxiliary beam 12 for accurately detecting the distribution state of the main beam 11 irradiated onto the track as shown in FIG. 4. It consists of auxiliary light-detecting pieces PDe and PDf. The four-segment photodetectors PDa, PDb, PDc, and PDd are composed of four photodetectors PDa, PDb, PDc, and PDd in the clockwise direction with respect to the track direction. The inner circumferential side of the main beam 11 includes PDa and PDb. The outer circumferential side of the main beam 11 is detected by PDc and PDd. The signal detector 28 processes the output signal of the photodetector PD to detect the high frequency signal RF and the tracking error signal Te. To this end, the signal detector 28 includes a comparator 32 for detecting the tracking error signal Te and an adder amplifier 34 for detecting the high frequency signal RF, as shown in FIG. 4. The output signal of the first auxiliary photodetecting piece PDe is input to the non-inverting terminal + of the comparator 32, and the output signal of the second auxiliary photodetecting piece PDf is input to the inverting terminal −. The comparator 32 detects the difference between the output signals of the first and second auxiliary photodetectors PDe and PDf as the tracking error signal Te. The detected tracking error signal Te is supplied to the tracking servo unit 26. The tracking servo unit 26 controls the actuator Ac of the optical pickup 24 according to the offset level included in the tracking error signal Te to move the objective lens OL in the inner or outer circumferential direction. Tracking control is performed such that the main beam 11 follows the light spot center moving line (... Bk-2, Bk-1, Bk, Bk + 1, Bk + 2 ...). The adder amplifier 34 adds and amplifies the output signals of the four-segment photodetectors PDa, PDb, PDc, and PDd to detect the high frequency signal RF, and supplies the high frequency signal RF to the reproduction signal processor 30. do. The reproduction signal processor 30 then decodes and reproduces the high frequency signal RF input thereto.

As described above, the optical recording medium according to the present invention can minimize the crosstalk between tracks since the track pitches of the adjacent tracks are different and the adjacent track signals can be excluded by the light spots irradiated toward the wide track pitches. It becomes possible. Furthermore, the optical recording medium according to the present invention has a high density recording capacity because the pit pattern spacing formed between adjacent tracks is minimized to maximize the number of tracks.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a diagram showing a track structure in a conventional optical disc.

2 shows a track structure of an optical recording medium according to an embodiment of the present invention;

3 is a block diagram showing an apparatus for reproducing an optical recording medium according to an embodiment of the present invention;

FIG. 4 is a detailed circuit diagram showing in detail the photodetector and signal detector of the optical pickup shown in FIG.

<Description of the symbols for the main parts of the drawings>

10,20: optical disk 10a, 20a: ft

10b: mirror area 22: bulk track

24: optical pickup 26: tracking servo unit

28: signal detector 30: playback signal processor

32: comparator 34: adder amplifier

Claims (26)

A pit row formed with at least two different track pitches, And a wide range irradiated to the pit rows is shifted and irradiated to one of the two different track pitches. The optical recording medium according to claim 1, wherein the center of the wide range is shifted and irradiated toward a wide track pitch. The optical recording medium of claim 1, wherein the track pitch has two track pitches, a first track pitch alternated by a predetermined track unit and a second track pitch wider than the first track pitch. The optical recording medium according to claim 3, wherein the first track pitch is equal to or more than a pit width. The optical recording medium according to claim 4, wherein the first track pitch is less than 1.5 times the pit width. 3. The optical recording medium according to claim 2, wherein a distance difference between the tracking center and the track center of the light beam is approximately one quarter of the light spot diameter. The optical recording medium according to any one of claims 1 to 6, wherein a light spot diameter of the light beam is larger than the first track pitch and less than or equal to the second track pitch. 7. The optical recording medium according to any one of claims 1 to 6, wherein the sides of the pits formed in adjacent tracks on the first track pitch side are in contact with each other. Pits rows are formed with different first and second track pitches, the first track pitch being narrower than the second track pitch, and the first track pitch being greater than the fit width and less than 1.5 times. An optical recording medium. 10. The optical recording medium according to claim 9, wherein the light beam irradiated to the pit rows is radiated toward the wide track pitch of the track pitches. 10. The optical recording medium according to claim 9, wherein an optical spot diameter of the light beam irradiated to the pit rows is larger than the first track pitch and less than the second track pitch. 10. The optical recording medium according to claim 9, wherein a distance difference between the tracking center and the track center of the light beam is approximately one quarter of the light spot diameter. 13. The optical recording medium according to any one of claims 9 to 12, wherein the pit rows formed on the track adjacent to the first track pitch are in contact with each other. In the data reproducing apparatus of the optical recording medium, Optical pickup for reproducing pit-shaped data recorded on an optical recording medium; A signal detector for detecting a signal reproduced from the optical pickup; And a servo control unit for controlling the optical pickup to reproduce the pit-shaped data, The pit-shaped data recorded on the optical recording medium includes a pit row formed with at least two different track pitches, and the servo control unit includes a light beam irradiated to the pit rows of the two different track pitches. And controlling the optical pickup to be shifted and irradiated to one side. 15. The apparatus of claim 14, further comprising a playback signal processing section for extracting a playback signal from the signal detected by the signal detection section. 15. The apparatus of claim 14, wherein the servo controller controls the optical pickup such that the center of the light beam is shifted and irradiated toward a wide track pitch. In the data reproduction method of an optical record carrier, Reproducing pit-shaped data recorded on the optical recording medium; And detecting the reproduced signal and outputting a reproduced signal, wherein the pit-shaped data recorded on the optical recording medium is formed of a pit row formed with at least two different track pitches. Control to accurately detect the pit rows formed by the different track pitches, and control the light beams irradiated to the pit rows to be shifted and irradiated to one of the two different track pitches. Way. In the data recording method of the optical recording medium, And recording the data to be recorded as pit-shaped data on the optical recording medium, wherein the pit-shaped data recorded on the optical recording medium is formed of a pit row formed with at least two different track pitches. , The first track pitch is formed narrower than the second track pitch, wherein the first track pitch is larger than the width of the pit and less than 1.5 times the width of the pit, And controlling the pit array to be recorded with the different track pitches. In the data reproduction method of an optical record carrier, Reproducing pit-shaped data recorded on the optical recording medium; And detecting the reproduced signal and outputting a reproduced signal, wherein the pit-shaped data recorded on the optical recording medium comprises a pit array formed with at least two different track pitches. The first track pitch is narrower than the second track pitch, and the first track pitch is larger than the width of the pit and is 1.5 times or less of the width of the pit. And a data reproducing method of the optical recording medium. 20. The method of claim 19, wherein the light beam irradiated to the pit rows is irradiated toward the wide track pitch among the track pitches. 20. The method of claim 19, wherein an optical spot diameter of the light beam irradiated to the pit rows is larger than the first track pitch and less than the second track pitch. 20. The method of claim 19, wherein the distance difference between the tracking center and the track center of the light beam is approximately one quarter of the optical spot diameter. And a pit row formed with at least two different track pitches, wherein the light spot diameter of the light beam irradiated to said pit row is greater than said first track pitch and less than said second track pitch. 24. The optical recording medium according to claim 23, wherein the light beam irradiated onto the pit rows is irradiated toward the wide track pitch among the track pitches. The optical recording medium according to claim 23, wherein the distance difference between the tracking center and the track center of the light beam is approximately one quarter of the light spot diameter. 26. The optical recording medium according to any one of claims 23 to 25, wherein the pit rows formed on the track adjacent to the first track pitch are in contact with each other.