GB2324903A - High-density read-only optical disk - Google Patents
High-density read-only optical disk Download PDFInfo
- Publication number
- GB2324903A GB2324903A GB9805177A GB9805177A GB2324903A GB 2324903 A GB2324903 A GB 2324903A GB 9805177 A GB9805177 A GB 9805177A GB 9805177 A GB9805177 A GB 9805177A GB 2324903 A GB2324903 A GB 2324903A
- Authority
- GB
- United Kingdom
- Prior art keywords
- optical disk
- data
- track
- grooves
- read
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
- G11B7/24073—Tracks
- G11B7/24076—Cross sectional shape in the radial direction of a disc, e.g. asymmetrical cross sectional shape
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0938—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following servo format, e.g. guide tracks, pilot signals
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
- G11B7/24073—Tracks
- G11B7/24079—Width or depth
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
- G11B7/261—Preparing a master, e.g. exposing photoresist, electroforming
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
- G11B2007/00709—Dimensions of grooves or tracks, e.g. groove depth, track pitch
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
- G11B2007/00754—Track shape, e.g. address or synchronisation information in wobbled track or sidewall
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Optical Record Carriers And Manufacture Thereof (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
A high-density read-only optical disk, such as a DVD. For each track on a recording surface of the optical disk, a groove (6) is formed and a plurality of data pits (4) are formed along the groove (6). Each groove has a wave-shaped (preferably U-shaped) transverse section, an arrangement that enables interference effect tracking at track pitches of less than 0.74 micrometers. Thus, data can be read from such a disk even with a track pitch P narrower than that of a conventional optical disk which has data pits (4) formed in each track directly onto a substantially planar recording surface.
Description
HIGH-DENSITY READ-ONLY OPTICAL DISK
The present invention relates to an optical disk system for recording digital audio or video data on a disk in the form of pits and reading the data by a laser beam, and in particular, to a read-only optical disk with a substrate surface structure for increasing data recording density.
In optical recording and reading technology, data is read from a disk by a laser beam depending on variations in the intensity of reflected light. The intensity of the reflected light is varied, that is, data is recorded on an optical disk by using optical interference between concave pits and a reference surface as in a conventional CD (Compact Disc) or DVD (Digital Video Disc), changing the deflection direction of an optomagnetic recording material as in an optomagnetic disk, using the difference between the intensities of reflected light according to states of a recording material as in a phase change disk, or varying organic pigments as in a CD-R (CD-Recordable). The optical disks are grouped into read-only, recording-once, and repeated recording and reading types according to whether and how many times they can be recorded.
A pickup for such an optical disk should track a series of successive data to read the data recorded on the optical disk. The principle of tracking is to use light diffracted when a laser beam is positioned over a pit so that the pickup may not deviate from an intended track.
Figure 1 is a view showing the angle e of thus-generated first-order diffracted light, given by the following equation (1). Reference numerals 2 and 4 in Figure 1 denote an optical disk substrate and pits, respectively:
sin e = A/p (1) where A is a laser wavelength, and p is a track pitch.
Data is tracked using a signal generated by interference effect between zero-order diffracted light and the first-order diffracted light in the optical disk system. With the track pitch p smaller than A, sin 6 becomes larger than 1, and no first-order diffracted light exists, as noted from equation (1). Then, the interference effect-dependent tracking is impossible.
This diffraction limit restricts p and, as a result, recording density in a conventional optical disk system.
Figure 2 illustrates an exemplary track structure of a conventional DVD. The DVD generally includes grooveshaped pits 4 with the track pitch p of 0.74pm on a polycarbonate substrate 2 with a diameter of 120mm and a thickness of 0.6mm, and an Al reflecting film coated on the pits 4. The data recording capacity of this DVD is, for example, 4.7GB per surface. A pickup for a conventional DVD player has a A of 650nm and an NA (Numerical Aperture) of 0.6. Because p is limited to 0.74m as described referring to Figure 1 and equation (1), the data recording capacity of the DVD shown in
Figure 2 is no more than 4.7GB. The current development trend of optical disks is toward high-density recording and high-speed reading of images for an HDTV (High
Definition TeleVision). This purpose can be achieved most easily by increasing disk area and the number of disk rotations. However, this method is not viable because the size of a disk and a reading device also increases. An effective and preferable alternative is to increase a recording density per unit area. To increase the recording density, a track pitch and a linear recording density should be increased by developing a practical laser with a shorter laser wavelength.
As a way to record more data on a 120mm-diameter disk such as the DVD of Figure 2, p is reduced from the conventional value 0.74pm to 0.6 or 0.5cm, resulting in an increase in the angle e of the first-order diffracted light, and deviation of the first-order diffracted light with a larger angle from a light receiving range of an object lens in the pickup. Therefore, it is impossible to track data on a high-capacity disk having a p of 0.6 or 0.5pm by a first-generation DVD player having predetermined A and NA. Even in case tracking is possible, data is read from an adjacent track, thereby generating noise and data read errors called crosstalk.
As a result, there is a need for a disk having a new structure to enable data to be read from a high-capacity disk (hereinafter, referred to as DVD) with a 0.6 or 0.5m track pitch in the conventional DVD player.
An aim of preferred embodiments of the present invention is to provide a high-density optical disk with a track structure for enabling data to be read in a conventional read-only DVD player.
Another aim of embodiments of the present invention is to provide a high-density optical disk with a track structure for overcoming the restriction of a track pitch caused by a diffraction limit.
According to a first aspect of the invention, there is provided a high-density read-only optical disk comprising: a plurality of grooves successively formed into waves along respective tracks; and a plurality of data pits formed in the grooves, whereby data can be read even with a track pitch narrower than that of an optical disk having only data pits in each track.
Said tracks are preferably formed in a recording surface of the disk, and a transverse cross-section of a track taken through a data pit has the form of a concave indentation in said recording surface, said indentation being said groove, and said data pit extending into said recording surface from a base region of said groove.
Preferably, the depth of the grooves is set to maximize scattering a data signal from an adjacent track.
The depth of the grooves is preferably in the order of tens of nanometers. The depth of the grooves in one preferred embodiment is substantially 25nm when a track pitch is 0.5cm.
In another preferred embodiment the depth of the grooves is substantially 20nm when a track pitch is 0.6cm.
Preferably, the pits and the wave-shaped grooves are formed by laser beam recording in a mastering process.
Thus, data can be read even with a track pitch narrower than that of an optical disk having only data pits in each track.
For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:
Figure 1 is a view referred to for describing light diffraction on an optical disk;
Figure 2 illustrates an exemplary track structure of a conventional DVD;
Figure 3 illustrates a track structure of a highdensity optical disk according to an embodiment of the present invention;
Figure 4 is a graph of variations in a tracking error signal with respect to wave-shaped groove depth according to the present invention; and
Figure 5 is a picture of high-frequency (HF) eye patterns displayed on an oscilloscope screen with respect to 3T-11T and 14T in a DVD with a 0.Spm track pitch according to the embodiment of the present invention.
Preferred embodiments of the present invention will be described in detail referring to the attached drawings.
It is to be noted that like reference numerals denote the same components in the drawings, and a detailed description of generally known function and structure of the present invention will be avoided lest it should obscure the subject matter of the present invention.
Figure 3 illustrates an exemplary track structure of a DVD according to an embodiment of the present invention.
As shown in Figure 3, the data recording capacity of the
DVD is increased by reducing its track pitch from 0.74m to 0.5cm. In order to eliminate tracking servo problems and crosstalk encountered in reading the DVD having the narrowed 0.5m track pitch with a conventional DVD player, a groove 6 comprising a concave indentation of arcuate cross-section is formed in the form of a wave in each track of the DVD, and data pits 4 are formed in the groove 6. Wave-shaped grooves 6 are successively arranged along tracks, and act to reduce the angle o of first-order diffracted light. The light diffracted at a smaller angle enters a light receiving range of a lens in a pickup, thereby making tracking servo possible.
The depth d of the wave-shaped grooves 6, which scatters a data signal from an adjacent track, is preferably set to maximize scattering of the data signal.
To describe this in detail, as the track pitch is narrowed, the data signal read from an adjacent track becomes too large for a planar surface as in a conventional disk, resulting in data read errors.
However, the pits 4 positioned in the base of the waveshaped grooves 6 scatter the data signal from an adjacent track in the embodiment of the present invention. That is, signals from a corresponding track and an adjacent track interfere with each other by the wave-shaped grooves 6 formed in the respective tracks, and are offset by controlling the depth d of the grooves 6. Thus, the narrowed track pitch-induced crosstalk is eliminated. The depth d of the grooves 6 is set to a value in a test to prevent occurrence of the crosstalk, which will be described later referring to Figure 4.
In general, optical disks including a DVD are fabricated by performing a sequence of mastering, stamper making, injection molding, sputtering, and other subsequent processes. In the mastering process, fine pits are formed on a photoresist by photolithography. Stamper making refers to the process of transcribing molds (i.e., stampers) in the pits to a thickness of about 0.3mm by plating, for enabling injection molding. Injection molding refers to the process of massively reading optical disk substrates, using the stampers. By sputtering, a reflecting film is formed.
The pits 4 and the wave-shaped grooves 6 in the embodiment of the present invention are formed by laser beam recording in the mastering process. A conventional
DVD is recorded by a single laser beam, whereas two laser beams are used in the embodiment of the present invention, one for forming the basic data pits, and the other for forming the wave-shaped groove. For formation of the basic data pits, one laser receives a modulated signal from a DVD formatter, and generates a laser beam corresponding to the size of the pits. For formation of the successive wave-shaped grooves, the other laser is controlled to make the spot size of a laser beam larger than that for forming the data pits, receives a predetermined DC (Direct Current) signal, and generates a laser beam of a constant size.
Tracking servo is possible even with a narrow track pitch by forming the wave-shaped grooves along a series of pit-in-tracks and thus reducing the angle of first-order diffracted light. A tracking error signal is determined by d, which depends on p.
Figure 4 illustrates variations of the tracking error signal with respect to d, observed in an experiment. It is noted from Figure 4 that an optimum tracking error signal can be obtained when d is 25nm for p of 0.5cm, and 20nm for p of 0.6cm, respectively.
Figure 5 shows HF eye patterns displayed on an oscilloscope screen with respect to 3T-llT and 14T in a
DVD with a track pitch of 0.5m according to the embodiment of the present invention. It is observed from the eye patterns that a sufficient reading signal can be obtained in the conventional DVD player.
A conventional DVD is compared with disks according to embodiments of the present invention as follows.
(Table 1)
track wave tracking capacity reading pitch depth error (GB) time (um) (nm) signal (minute) conventional 0.74 0 3.0 4.7 120 DVD embodiment 1 0.60 20 3.5 6.0 150 embodiment 2 0.50 25 3.2 7.0 180 As shown in table 1, for example, embodiment 2 accommodates 180-minute readable data, relative to 120minute readable data of the conventional DVD. This implies an about 1.5-times increase in capacity.
As described above, the DVD structure of the present invention enables long and high-resolution image data to be read in the conventional DVD player. In the case of a laser source with a short wavelength (e.g. a laser with a 532nm green wavelength or a 450nm blue wavelength), the conventional DVD player can read data even with a 0.4 or 0.3m track pitch by employing the DVD structure of the present invention. That is, no tracking error or crosstalk is generated. When a pickup for the DVD player is designed to have a short wavelength, a higher-capacity
DVD can be realized than the above-described embodiments.
While the present invention has been illustrated and described with reference to the specific embodiments, it is clearly understood that many variations can be made by anyone skilled in the art within the scope and spirit of the present invention. Thus, the appropriate scope hereof is deemed to be in accordance with the claims as set forth below.
The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
Claims (8)
1. A high-density read-only optical disk comprising:
a plurality of grooves successively formed into waves along respective tacks; and
a plurality of data pits formed in the grooves,
whereby data can be read even with a track pitch narrower than that of an optical disk having only data pits in each track.
2. A disk according to claim 1, wherein said tracks are formed in a recording surface of the disk, and wherein a transverse cross-section of a track taken through a data pit has the form of a concave indentation in said recording surface, said indentation being said groove, and said data pit extending into said recording surface from a base region of said groove.
3. The high-density read-only optical disk as claimed in claim 1 or 2, wherein the depth of the grooves is set to maximize scattering a data signal from an adjacent track.
4. The high-density read-only optical disk as claimed in claim 3, wherein the depth of the grooves is in the order of tens of nanometers.
5. The high-density read-only optical disk as claimed in claim 4, wherein the depth of the grooves is substantially 25nm when a track pitch is 0.5cm.
6. The high-density read-only optical disk as claimed in claim 4, wherein the depth of the grooves is substantially 2Onm when a track pitch is 0.6ym.
7. The high-density read-only optical disk as claimed in one of claims 1-5, wherein the pits and the wave-shaped grooves are formed by laser beam recording in a mastering process.
8. A high-density read-only optical disk substantially as herein described with reference to Figures 3 to 5.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019970016072A KR19980078521A (en) | 1997-04-29 | 1997-04-29 | High-density playback-only optical disc |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9805177D0 GB9805177D0 (en) | 1998-05-06 |
| GB2324903A true GB2324903A (en) | 1998-11-04 |
| GB2324903B GB2324903B (en) | 1999-05-19 |
Family
ID=19504229
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9805177A Expired - Fee Related GB2324903B (en) | 1997-04-29 | 1998-03-12 | High-density read-only optical disk |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH10320834A (en) |
| KR (1) | KR19980078521A (en) |
| CN (1) | CN1133161C (en) |
| GB (1) | GB2324903B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4310916A (en) * | 1979-09-27 | 1982-01-12 | U.S. Philips Corporation | Optical record carrier and apparatus for reading it |
| US4587648A (en) * | 1982-08-10 | 1986-05-06 | Tokyo Shibaura Denki Kabushiki Kaisha | Optical disk |
| EP0193614A1 (en) * | 1984-09-04 | 1986-09-10 | Matsushita Electric Industrial Co., Ltd. | Disk-shaped record carrier |
| US4674070A (en) * | 1984-08-11 | 1987-06-16 | Victor Company Of Japan, Ltd. | Optical type disc with V-shaped groove and optical type reproducing apparatus therefor |
| US5210738A (en) * | 1990-06-15 | 1993-05-11 | Pioneer Electronic Corporation | Optical information recording medium |
-
1997
- 1997-04-29 KR KR1019970016072A patent/KR19980078521A/en not_active Application Discontinuation
-
1998
- 1998-03-12 GB GB9805177A patent/GB2324903B/en not_active Expired - Fee Related
- 1998-04-07 CN CN98106232A patent/CN1133161C/en not_active Expired - Fee Related
- 1998-04-15 JP JP10105042A patent/JPH10320834A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4310916A (en) * | 1979-09-27 | 1982-01-12 | U.S. Philips Corporation | Optical record carrier and apparatus for reading it |
| US4587648A (en) * | 1982-08-10 | 1986-05-06 | Tokyo Shibaura Denki Kabushiki Kaisha | Optical disk |
| US4674070A (en) * | 1984-08-11 | 1987-06-16 | Victor Company Of Japan, Ltd. | Optical type disc with V-shaped groove and optical type reproducing apparatus therefor |
| EP0193614A1 (en) * | 1984-09-04 | 1986-09-10 | Matsushita Electric Industrial Co., Ltd. | Disk-shaped record carrier |
| US5210738A (en) * | 1990-06-15 | 1993-05-11 | Pioneer Electronic Corporation | Optical information recording medium |
Non-Patent Citations (1)
| Title |
|---|
| Jap. J. of App.Phys. Pt.1, 36 (no.1B), 1997, S Morita et al.pp. 444-449 * |
Also Published As
| Publication number | Publication date |
|---|---|
| KR19980078521A (en) | 1998-11-16 |
| CN1208920A (en) | 1999-02-24 |
| GB2324903B (en) | 1999-05-19 |
| GB9805177D0 (en) | 1998-05-06 |
| CN1133161C (en) | 2003-12-31 |
| JPH10320834A (en) | 1998-12-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1001410B1 (en) | Optical recording medium and master for manufacturing same | |
| US5407720A (en) | Optical recording medium and process for producing the same | |
| US6487164B1 (en) | Optical recording medium capable of assuring sufficient levels of signals required for reading/writing data, and stamper for manufacture of the same | |
| US6791938B2 (en) | Optical recording medium, master disc for the preparation of the optical recording medium and optical recording and/or reproducing apparatus | |
| US7242662B2 (en) | Optical recording/reproducing medium, mother stamper for producing optical recording/reproducing medium and optical recording/reproducing device | |
| US6654337B2 (en) | Magneto-optical recording medium having pit pitch greater than groove pitch | |
| JPH0481816B2 (en) | ||
| TW579515B (en) | Optical disc and information reproducing apparatus for same | |
| KR100913509B1 (en) | Optical recording medium, master disc for manufacturing optical recording medium, and device and method for manufacturing master disc for manufacturing optical recording medium | |
| US7251211B2 (en) | Optical medium having grooves along recording tracks, and an associated master disc and apparatus | |
| US6934244B2 (en) | Optical recording medium and stamper for manufacturing the same | |
| GB2324903A (en) | High-density read-only optical disk | |
| JPWO2003041064A1 (en) | Optical recording / reproducing medium, optical recording / reproducing medium manufacturing stamper, and optical recording / reproducing apparatus | |
| US6349085B1 (en) | High density recording medium with pit width to track pitch ratio in the range of 0.4 to 0.55 for push-pull tracking servo control | |
| JP2848992B2 (en) | Optical recording medium and substrate for optical recording medium used therefor | |
| JP4320916B2 (en) | Optical recording medium, master for manufacturing optical recording medium, and optical recording / reproducing apparatus | |
| EP0751505A2 (en) | Optical information-recording medium | |
| JP4320915B2 (en) | Optical recording medium, master for manufacturing optical recording medium, and optical recording / reproducing apparatus | |
| JPH09293274A (en) | Optical recording medium | |
| JP2003346385A (en) | Optical recording and reproducing medium, its manufacturing origin plate, optical recording and reproducing method | |
| JP2003208719A (en) | Optical recording/reproducing medium, stamper for producing optical recording/reproducing medium and optical recording /reproducing device | |
| JPH11296909A (en) | Recording medium and master disk for manufacturing recording medium | |
| JP2004178651A (en) | Optical recording and reproducing medium, and optical recording and reproducing device using the same | |
| KR20110047221A (en) | Compatible optical recording media | |
| JPH06282848A (en) | Optical disc player |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20090312 |