US20070053266A1 - Device and method for reading multilayer optical disk - Google Patents
Device and method for reading multilayer optical disk Download PDFInfo
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- US20070053266A1 US20070053266A1 US11/595,063 US59506306A US2007053266A1 US 20070053266 A1 US20070053266 A1 US 20070053266A1 US 59506306 A US59506306 A US 59506306A US 2007053266 A1 US2007053266 A1 US 2007053266A1
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- 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
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/005—Reproducing
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- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
- G11B7/1263—Power control during transducing, e.g. by monitoring
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- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
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- G11B20/00572—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which change the format of the recording medium
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- 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
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- 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
- G11B7/0901—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 for track following only
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- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
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- 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
- G11B7/24085—Pits
- G11B7/24088—Pits for storing more than two values, i.e. multi-valued recording for data or prepits
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Optical Recording Or Reproduction (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
Abstract
Device and method for reading multilayer optical disk The invention refers to a device and a method for scanning an optical data carrier (1) by means of a main scanning beam (3) being reflected by the data carrier (1) and being detected by means of a photodetector (10), the data carrier (1) having first and second layers (11,12) to be scanned, the second layer (12) being scanned through the first layer (11), light passing the first layer (11) being shaded dependent on local properties of the first layer (11).
An object of the invention is to propose a device having increased performance even for use with multi layer disks (1) having a layer (11) causing light fluctuations on a layer (12) to be scanned, as well as a respective method.
According to the invention such device is provided with means (2,7,17) for keeping an output signal (D) of the photodetector (10) independent of variations of shading.
Description
- The invention refers to a device and a method for reading and/or writing dual layer or multi layer optical disks, also referred to as scanning such optical data carriers. Use of multiple layers is one possibility to increase storage capacity of an optical disk. Amongst others, phase-change dual-layer recording is regarded to be one of the most promising technologies for recording optical disks. A dual layer disk is provided with a first layer which is semi-transparent and partly reflective, and a second layer which is reflective. The second layer is scanned with a beam of light that passes through the first layer. In case of a partly written first layer or in case of a disk according to a so-called hard-sectorized format the first layer causes light intensity fluctuations on the second layer due to different light transmission in already written areas and areas not yet written to. These light fluctuations are also referred to as shading or shading effect in the following. According to said hard-sectorized formats sectorization is done for example by pre-embossed markings, the so-called pre-pits. A pre-pit area is an example of an already written area, a recorded area is another example. Hard sectorized formats are e.g. based on land/groove and prepit structure as e.g. used for the known DVD-RAM standard. The light fluctuations on the second layer mentioned above significantly reduce read out performance and recording signal quality. This is especially the case if phase-change recording layers are used as these are very sensitive on recording laser power changes. However, the problem mentioned above occurs not only with dual layer phase-change materials, but with all multi-layer disks in combination with materials, where information is stored in sequences that cause dark and bright sequences in the transmitted light. Such dark and bright sequences may have several causes, e.g. different reflectivity, different absorption factors or different interference behaviour, destructive/constructive, of different areas of a layer, or differences in other properties having similar effect. The different layers may be of a single type or of different types, as recordable, pre-recorded or non-recorded.
- It is an object of the invention to propose a device having increased performance even for use with multi layer disks having a layer causing light fluctuations on a layer to be scanned, as well as a respective method.
- According the invention this object is solved by the features indicated in the independent claims. Advantageous features are also indicated in the dependent claims.
- A device according to the invention for scanning an optical data carrier by means of a main scanning beam being reflected by the data carrier and being detected by means of a photodetector, the data carrier having first and second layers to be scanned, the second layer being scanned through the first layer, light passing the first layer being shaded dependent on local properties of the first layer, is provided with means for keeping an output signal of the photodetector and, if provided for, a following amplification circuit independent of variations of shading. This has the advantage that an output signal which lies within a certain constant range is easy to further process, independent of the quality or the status of the shading causing layer.
- The device comprises advantageously a scanning beam generating means having variable intensity control, the intensity being varied in proportion to the amount of shading. Also advantageously, it comprises an output signal amplifier having variable gain, the gain being varied in proportion to the amount of shading. Of course, also a combination of both features has positive effects. The changing transmission of the semitransparent layer or shading caused by it is detected by special means of the optical head of the device. In case that the beam generating means is a laser, the laser power is changed accordingly to compensate the shading. The laser power is tuned such that—independently whether the light is transmitted through a written area or a non-written area, or through the data area or the prepit area—no light intensity fluctuations occur on the recording surface during recording and no light intensity changes occur on the detector of the optical head during readout. For readout the compensation of the shading is preferably done via variation of the gain of the amplifier for the output signal of the photodetector. As the laser power should not exceed a certain level during readout, since data erasing could occur in this case, variation of gain is more appropriate for readout. However, also a combination of gain change and laser power change is advantageous e.g. because the variation range for the gain change is smaller in this case.
- Advantageously, the device further comprises a beam generator for generating a shading detection beam, a photodetector for detecting said beam and delay means for delaying an output signal of said photodetector. In this way shading detection is easily and reliably performed. The beam generator is either a light source as a laser, a beam splitter as a semitransparent mirror, a grating or a holographic optical element, or another appropriate element. The shading detection beam is arranged ahead of the scanning beam, seen in scanning direction. It thus reaches an area of different shading earlier than the main scanning beam. This leaves sufficient time to prepare for timely adaptation of laser power or amplifier gain or both. Preferably the detection beam is a preceding beam that is generated anyway for other purposes, e.g. for use in a three-beam scanning method where a tracking error signal is generated from side beams or using side beams to correct a signal generated from the main beam, as it is the case for the so-called well-known Differential Push Pull method. The distance, at the scanned layer, between detecting beam and main scanning beam is preferably chosen much larger then necessary for switching of power or gain. This makes possible to increase scanning speed or to perform additional tasks before shading occurs. Advantageously the shading detection beam signal is delayed, e.g. via a simple delay line or by being stored in a memory, so as to be available at the time where it is needed to initiate switching. Preferably the delay time is variable in order to make possible adaptation, e.g. to different scanning speeds, different speed of switching process, different data carrier properties or other properties that might alter or change in time or on other circumstances. It is also advantageously possible to use as detection beam a beam being arranged a relatively big distance ahead of the main scanning beam, e.g. arranged 90° or 180° degrees ahead, but scanning the same or nearly the same track. It is also one of the inventive solutions to determine shading effects by the main beam itself or a succeeding beam and to delay the respective signal for the time of a complete or nearly complete rotation of the disk. Another solution according to the invention lies in the fact that the beginning of a shading area is predicted from the location of an indicative position on the track, the distance from which to the shading area is known, and the disk rotation speed. For example the pre-pit areas are arranged according to predefined rules so that the beginning of a shading pre-pit area can be predicted from the time elapsed after having passed the preceding one.
- A method for scanning an optical data carrier according to the invention comprises the steps of detecting variations of shading of the second layer and changing at least one of intensity of main scanning beam and amplification of photodetector output signal in proportion to the detected variations. This has the advantage, apart from those already indicated above, that it does not require a special process for the production of dual layer disks, but solves the object of the invention within the device.
- Preferably a method according to the invention provides for detection of variations of shading by detecting intensity of a shading detection beam scanning the data carrier. Preferably the detected intensity signal is low-pass filtered. This has the advantage that high frequent disturbances, as such caused by the data stored on the disk or by high frequent variation of laser power, do not occur in the low-pass filtered signal. As already described above, it is advantageous to delay the intensity signal in dependency on the distance between shading detection beam and scanning beam, or in dependency on a known distance between a first indicative position and a second shading position.
- According to the invention a method for preparing for scanning an optical data carrier having first and second layers to be scanned, the second layer being scanned through the first layer, light passing the first layer being shaded dependent on local properties of the first layer, provides for compensation of local differences in shading effect by providing the first layer with a shading pattern. That means that areas of the first layer that have a low shading effect are intentionally provided with a shading causing or increasing pattern. This pattern is designed such that it does not have an influence of reading from or writing to the first layer but ascertains sufficient shading for not having intensity fluctuations on the second layer. An advantage of this method is that it is to be performed only once, at the first writing on the first layer. All non-written areas may be provided then with a shading pattern and all pre-pit areas or similar areas are also provided with sufficient shading. Of course, the disk may also be pre-formatted during production or before being provided to the customer, so that direct access to both or all of the layers is possible without suffering from fluctuations.
- Although the complete disk may be provided with a shading pattern according to the invention, it is especially advantageous to provide a shading pattern only in areas having predetermined characteristics, as the pre-pit areas or other areas having pre-embossed patterns. In case of a phase-change disk the transmission properties of the pre-pit areas are changed, during first recording of the semi-transparent first layer, to the same level as the recorded data area. Depending on the initial phase-change state of the disk, e.g. un-initialized disk with amorphous recording layer or initialized disk with crystallized layer, this can be done by erasing or writing a certain pattern in the prepit area. Certain in this case means that the shading pattern, of course, is to be chosen such as not disturb the readout of the pre-pit information.
- According to the invention the shading pattern is either a grey level pattern or a pit pattern the pits of which are larger than the largest data recording pits or a pit pattern the pits of which being smaller than the smallest data recording pits. The certain recorded or erased pattern is e.g. a grating structure, where adjacent tracks are amorphous-crystalline-amorphous-crystalline-etc. with bright-dark-bright-dark-etc. stripes. It is to be noted that different phase-change materials and/or layer stack designs exist. High-to-low or low-to-high materials/stacks means here that the ground state has high reflectivity or low reflectivity, respectively. However, ground state is usually supposed to be crystalline. Averaged over several tracks the reflectivity or, more important, the transmission is the same or nearly the same for pre-pit areas as for the data areas, where dark and bright data pits are recorded. The grating structure according to the invention, i.e. where the pattern is either a grey one or the pits of the shading pattern are either much larger or much smaller than the data pits or the pre-pits, assures that it does not degrade the readout of the pre-embossed pre-pits. Also a grating structure having stripes arranged in track direction but having a much smaller width lie within the scope of the invention.
- Advantageously the shading pattern is also used to store additional information. Especially in the case of shading pits length or distance variations of these pits or different distinguishable grey levels may be used to store information as recording parameters, indication of the device, date of recording, copyright information, encryption parameters etc. Even if such information should, at present, not being readable by means of mass produceable devices, it might be applicable for copyright issues or for use with future devices being able to detect much larger or smaller pits.
- Data carriers being provided with a shading pattern according to the invention as well as devices performing a method according to the invention also lie within the scope of the invention. This is also the case for combinations of features not especially named herein or changes of design lying within the scope of a skilled person. Further variants and advantages of the invention are also included in the following description of preferable embodiments using figures.
- In the figures:
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FIG. 1 shows a device according to the invention -
FIG. 2 shows a track structure with shading pattern according to the invention -
FIG. 3 shows another track structure with shading pattern according to the invention -
FIG. 4 shows a different type of shading pattern according to the invention -
FIG. 5 shows a further type of shading pattern according to the invention -
FIG. 1 shows a device according to the invention in a diagrammatic view. The optical data carrier is in this embodiment adisk 1, being shown in a partial cross sectional view. Dimensions are not to scale in order to more clearly show relevant features.Disk 1 is provided with afirst recording layer 11 and asecond recording layer 12.First layer 11 is a semitransparent layer whilesecond layer 12 is a reflecting layer.Transparent cover layer 13 andintermediate layer 14 are provided but not described in detail here. At the right part of layer 11 a stack oflayers 15 is indicated, as instead of asingle layer 11 also several layers may be arranged abovelayer 2. However, only asingle layer 11 will be described here, as application to a stack oflayers 15 is a task within the scope of a skilled person. - The device comprises as light source a
semiconductor laser 2 generating ascanning beam 3. Thelaser 2 is provided to be driven with different power. This enables the device to perform recording, adaptation to different types ofdisk 1 and adaptation according to the invention as described below.Beam 3 is collimated by a collimator 4, passes through abeam splitter 5 and is focused by an objective lens 6 onto thesecond layer 12. A grating 7 is provided in the path ofbeam 3 for generating, apart from themain scanning beam 3,secondary beams 3′, 3″, of which one is used as ashading detection beam 3′.Shading detection beam 3′ is arranged thus that it precedesmain scanning beam 3 on thedisk 1 in direction of scanning.Beam 3′ is shown separately frommain beam 3 at the lower part ofFIG. 1 in an exaggerated way, as well asside beam 3″.Beams second layer 12, directed bybeam splitter 5 to a focussinglens 8 and focussed bylens 8 onto aphotodetector 10. -
Photodetector 10 comprises three detector areas 9, 9′, 9″ onto which beams 3, 3′, 3″ fall, respectively. Detector areas 9, 9′, 9″ are each subdivided into 2 or more detector elements in order to generate detector signals D necessary for performing control functions as focus control or tracking control and for generating a data signal according to known methods. By way of example, the astigmatism method may be implemented as focussing method, using detector area 9, the differential push pull method DPP, using all detector areas 9, 9′, 9″, may be implemented as tracking method. Elements necessary to perform these functions are known to the skilled person and are thus not depicted here. - Output signal D′ of detector area 9′ is supplied to a low-
pass filter 16, the low-pass filtered signal DL is provided to anamplifier 17′ having variable gain G′ and output as shading detection signal SD. As an alternative solution, shading detection signal SD is supplied to adelay element 18 having a variable delay time T. The output signal ofdelay element 18 is the delayed shading detection signal SD′.Similar amplifiers -
Scanning beam 3 is focussed onto thesecond layer 12 as asmall scanning spot 22 while its cross section with thefirst layer 11 is anenlarged spot 21. Thisenlarged spot 21 covers an area of dark and bright areas and is thus shaded by the dark areas. The ratio between dark and bright areas is constant in case of a completely written area covered byspot 21. It is not constant in case also non-written areas fall withinspot 21. Thus, different shading occurs in such cases, the intensity of the light formingscanning spot 22 fluctuates as the shading does. - During
scanning disk 1, a forthcoming obscurity due to shading caused by the semi-transparentfirst layer 11 is probed by an additional, leading spot, here by ascanning spot 22′ ofshading detection beam 3′. Thisspot 22′ is ahead of themain spot 22. The separation distance betweenmain spot 22 and leadingspot 22′ is designed to allow timely laser power change or amplifier gain switching respectively, if shading occurs. Since the detection signal caused by shading is of low frequency, it is low-pass filtered and is thus not degraded by the data signal or rf laser modulation, both having high frequency. In case that so-called differential push-pull tracking method is applied, the leadingspot 22′ of the threebeams first layer 11. - That means that the device according to the invention detects changes in the reflected intensity of
shading detection beam 3′ before the main readout beam is affected. This time difference is sufficient to switch gain for the main beam at exactly the time when the main beam intensity changes. This means that there is practically no change in the electronical readout signal of the main beam although shading is present. -
FIG. 2 shows, in a diagrammatic way, a small part of the track structure of thefirst layer 11 of amulti layer disk 1 in top view.Several tracks 19 are arranged in parallel, thecentre 20 of eachtrack 19 is indicated by a dotted line. Indicated by a circle is theenlarged spot 21 ofmain scanning beam 3. Each track is provided with data markings, also namedpits FIG. 2 there are depicteddata areas 26 which extend much longer to the respective sides than indicated here. Between thedata areas 26 there is arranged aheader area 25. In case of a hard-sectorized disk 1, theheader area 25 is provided with pre-embossed, permanent pits, so-calledpre-pits 23. The pre-pits 23 are permanent, i.e. they cannot be written or deleted by a recording device. In the example shown inFIG. 2 , pre-pits 23 are arranged only on one half of a track, either the one adjacent to thedata area 26 on the left or to the one on the right. Thepits 24 in thedata area 26 are arranged on every track, provided that thelayer 11 is already recorded. In the example shown thedata area 26 consists oftracks 19 having a pre-embossed land-and-groove structure. Eachland 27 is indicated in the drawing by a white background colour while eachgroove 28 is indicated with a dark background colour. Although this dark background is similar to the one in which thepits pits 24 do.Pits 24 are recordable that means they are not present on a non-recorded layer and they may be erased from a recorded layer. In any case, pits 24 of adata area 26 cause a difference in light reflected by them, usually described as dark and bright difference, i.e. they cause shading of a layer below their own layer. This is different for the pre-pits 23 which do not induce shading as they do not have a similar shading effect as pits 24. In thedata area 25, according to the invention, there is provided ashading pattern 29 consisting of pits much larger in length than the maximum length ofpits - During the first recording of the
semitransparent layer 11, theheader area 25 is provided with a dark-bright pattern 29, which makes it in the far-field domain as transparent or reflective as the recordeddata area 26. That means there is a similar shading effect onsecond layer 12 caused by theheader areas 25 as well as by thedata areas 25 offirst layer 11. Theshading pattern 29 is here a grating structure with alternating dark/bright stripes, parallel to theprepits 23. However, any other structure of shading pattern that does not disturb readout of the prepit information, is also applicable. - Two cases for providing a pattern in the prepit area as described above are described in the following:
- First,
layer 11 is assumed to be completely non-initialized, which means that the recordable material of thesemitransparent recording layer 11 is not in the crystalline ground state. In this case the recording layer needs to be initialized before the first recording. That means that thecomplete data area 26 has to be transformed to be in the crystalline ground state. It is completely initialized and the prepit area is provided with an alternating dark-bright pattern as described above. There are several possibilities to perform initialization, e.g. in a commercial drive using standard erase power, like continuous laser power, or in a special initializer equipment during the manufacturing process. The applied erase process with constant laser power does not disturb the readout of the prepit information. Another solution, not explicitely shown inFIG. 2 , is not to write a dark-bright pattern 29, but a homogeneous grey level, which has the same optical transmittance as the recordeddata area 26. This is possible for some materials having respective properties, using moderate laser power, i.e. at a power level that lies between erase power and maximum laser power. - Secondly,
layer 11 is assumed to be completely initialized, that means therecording layer 11 is in the crystalline ground state. In this case only theheader area 25 needs to be provided with a dark-bright pattern as described above. This is done preferably by applying high writing laser power to write an amorphous pattern in theheader area 25. For some materials the writing power is to be held constant, for other materials the writing power needs to be high frequency modulated, depending on respective material properties. High frequency modulation of the layer power may disturb readout of theprepits 23. In case of an embossed header area as depicted inFIG. 2 this problem is solved by writing only in the area not provided withprepits 23. In the areas provided withprepits 23 laser read power is applied. Since areas free ofprepits 23 and areas provided withprepits 23 alternate in the embossedheader area 25, in the far-field domain the reflectivity or transmission is homogeneously changed. -
FIG. 3 shows a similar part offirst layer 11 as shown inFIG. 2 . Same parts are indicated by same reference numbers and only referred to if different toFIG. 2 . The pre-pits 23 in theheader area 25 are arranged off-centre, in the example exactly at an intermediate position between two adjacent track centres 20. For example according to the DVD-RAM standard such off-centred so-called wobble pits are used as pre-pits 23. In this case the Sector ID is repeated twice, in each of the off-centred prepit areas. For such DVD-RAM type embossed header area, the same shading pattern as described with regard toFIG. 1 may be applied, but system redundancy is decreased. It is therefore preferrable to apply writing laser power only on one half of the track in theheader area 25, as shown inFIG. 2 . In this case 50% of theprepits 23 may be unreadable during writing of the shading pattern. However, this usually is still sufficient to correctly readout the sector ID. -
FIG. 5 shows another way to provide for ashading pattern 29 in case of off-centredpre-pits 23. For simplicity reasons neither pre-pits 23 norpits 24 are shown, but only the different types oftrack 19,land 27 andgroove 28. Different toFIG. 2 and 3,several data areas 26 andseveral header areas 25 are shown. It can be seen that for eachtrack 19 there is provided ashading pattern 29 in acomplete header area 25, while the followingheader area 25 of the same track is completely free of shading pattern. That means according to this alternative solution only everysecond header area 25 is read completely and ashading pattern 29 is written to theheader areas 25 between. Here, too, system redundancy is slightly reduced. -
FIG. 4 shows a small part of aheader area 25 with threeadjacent tracks 19, two of them havingpre-pits 23 in the figure. The shading pattern consists here oftiny pits 30, being of much smaller axial length, seen in axial direction of thetrack 19, than the pre-pits 23. These verysmall pits 30 are not detectable by the limited resolution of the optics usually provided for or the limited modulation transfer function (MTF) usually used. The size of afocused spot 32 ofscanning beam 3 on thislayer 11 is indicated here. It can be seen that it is too large to detect a single one oftiny pits 30. - It is to be noted that the invention refers mainly to shading effect. Shading effect denotes the low frequency change of the transmission properties of a first layer through which a second layer is scanned. These transmission properties change depending on if the first layer is recorded or unrecorded. In contrast thereto, high frequency variation of the second layer readout intensity occurs caused by varying spacial distribution of pits or other data markings of the first layer through which the scanning light beam passes before and/or after scanning the second layer. Such high frequency variations are often referred to as interlayer crosstalk.
- Although, according to the invention, no special process for dual layer disk manufacturing is required, it is of course advantageous to produce
disks 1 already provided with a shading pattern. Especially in case that a grey pattern is used, this can be easily performed in a simple additional production step or in a slightly changed initialization process. In case of changing of transmission property of thesemi-transparent header area 25 during first recording process no special optical head is required. To increase storage capacity of optical disks, multi-layer recording on phase-change materials is a very promising technology. In combination with continuous or soft-sectorized formats like DVD+RW or DVD-RW no shading problem on the deepersecond layer 12 occur, if the semitransparentfirst layer 11 is recorded completely. However, in case of hard-sectorized, land/groove formats theembossed header area 25 of the semi-transparentfirst layer 11 causes light fluctuations on thesecond layer 12. According to the invention several methods to avoid or to compensate light intensity fluctuations on thesecond layer 12 caused by an inhomogeneous, in terms of reflection and transmission, semi-transparentfirst layer 11 are proposed. Inhomogenities mainly occur in combination with non-continuous land/groove formats with embossedheader areas 25. According to one solution themultilayer disk 1 is pre-processed in the recording device before or during the first recording session. In this case the standard disk manufacturing process can be used.
Claims (10)
1-5. (canceled)
6. Method for preparing for scanning an optical data carrier having first and second layers to be scanned, the second layer being scanned through the first layer, light passing the first layer being shaded dependent on local properties of the first layer, having the step of providing the first layer with a shading pattern for compensating for local differences in shading effect.
7. Method according to claim 6 , wherein the shading pattern is provided only in areas having predetermined characteristics.
8. Method according to claim 6 , wherein the shading pattern is either a grey level pattern or a pit pattern, the pits of the pit pattern being either larger than the largest data recording pits or smaller than the smallest data recording pits.
9. Method according to claim 6 , wherein the shading pattern is used to store additional information.
10. Device for performing a method according to claim 6 .
11. Optical data carrier having first and second layers to be scanned, the second layer being scanned through the first layer, light passing the first layer being shaded dependent on local properties of the first layer, wherein the first layer has a shading pattern for compensating for local differences in shading effect.
12. Optical data carrier according to claim 11 , having said shading pattern only in areas having predetermined characteristics.
13. Optical data carrier according to claim 11 , wherein the shading pattern is either a grey level pattern or a pit pattern, the pits of the pit pattern being either larger than the largest data recording pits or smaller than the smallest data recording pits.
14. Optical data carrier according to claim 11 , wherein the shading pattern is used to store additional information.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/595,063 US20070053266A1 (en) | 2000-11-10 | 2006-11-09 | Device and method for reading multilayer optical disk |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP00124632A EP1205918A1 (en) | 2000-11-10 | 2000-11-10 | Device and method for reading multilayer optical disk |
EP00124632.1 | 2000-11-10 | ||
US10/416,263 US7158471B2 (en) | 2000-11-10 | 2001-10-29 | Device and method for reading multilayer optical disk with compensation of shading effects |
US11/595,063 US20070053266A1 (en) | 2000-11-10 | 2006-11-09 | Device and method for reading multilayer optical disk |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US10/416,263 Division US7158471B2 (en) | 2000-11-10 | 2001-10-29 | Device and method for reading multilayer optical disk with compensation of shading effects |
Publications (1)
Publication Number | Publication Date |
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US20070053266A1 true US20070053266A1 (en) | 2007-03-08 |
Family
ID=8170348
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US10/416,263 Expired - Fee Related US7158471B2 (en) | 2000-11-10 | 2001-10-29 | Device and method for reading multilayer optical disk with compensation of shading effects |
US11/595,063 Abandoned US20070053266A1 (en) | 2000-11-10 | 2006-11-09 | Device and method for reading multilayer optical disk |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
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US10/416,263 Expired - Fee Related US7158471B2 (en) | 2000-11-10 | 2001-10-29 | Device and method for reading multilayer optical disk with compensation of shading effects |
Country Status (9)
Country | Link |
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US (2) | US7158471B2 (en) |
EP (2) | EP1205918A1 (en) |
JP (1) | JP3972817B2 (en) |
KR (1) | KR20030044000A (en) |
CN (1) | CN1229786C (en) |
AU (1) | AU2002227900A1 (en) |
DE (1) | DE60138128D1 (en) |
TW (1) | TW577045B (en) |
WO (1) | WO2002039439A2 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP3889673B2 (en) * | 2002-06-19 | 2007-03-07 | パイオニア株式会社 | Information recording apparatus and control method thereof |
JP2008243332A (en) * | 2007-03-28 | 2008-10-09 | Toshiba Corp | Optical storage medium recording and playback device and tracking control method |
US7693030B2 (en) * | 2007-04-13 | 2010-04-06 | International Business Machines Corporation | Dual-path optical recording media and an apparatus for accessing thereof |
US8023384B2 (en) * | 2007-04-13 | 2011-09-20 | International Business Machines Corporation | Computer program product for controlling an apparatus for accessing dual-path optical recording media |
Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5373499A (en) * | 1993-07-22 | 1994-12-13 | International Business Machines Corporation | Multilayer optical disk and system having multiple optical paths include identical total disk substrate thickness |
US5414451A (en) * | 1991-10-11 | 1995-05-09 | Hitachi, Ltd. | Three-dimensional recording and reproducing apparatus |
US5559784A (en) * | 1993-03-26 | 1996-09-24 | Fuji Xerox Co., Ltd. | Multi-layer optical information detection by two laser beam and optical multilayer recording medium |
US5627816A (en) * | 1992-11-26 | 1997-05-06 | Matsushita Electric Industrial Co., Ltd. | Multilayer optical disk and apparatus |
US5905702A (en) * | 1992-04-10 | 1999-05-18 | Canon Kabushiki Kaisha | Optical information recording apparatus and method capable of coping with a plurality of card-like recording mediums of different reflectances |
US6101157A (en) * | 1997-06-27 | 2000-08-08 | Pioneer Electronic Corporation | Apparatus and method for focus control of read light irradiated on a recording surface |
US20020051414A1 (en) * | 2000-10-23 | 2002-05-02 | Pioneer Corporation And Tohoku Pioneer Corporation | Multi-layer information recording medium and recording apparatus for the same |
US6434095B1 (en) * | 1995-04-07 | 2002-08-13 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium, manufacturing method therefor, manufacturing apparatus therefor, and optical information recording and reproducing apparatus |
US6456584B1 (en) * | 1998-05-15 | 2002-09-24 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium comprising a first layer having a phase that is reversibly changeable and a second information layer having a phase that is reversibly changeable |
US6511788B1 (en) * | 1999-02-12 | 2003-01-28 | Sony Corporation | Multi-layered optical disc |
US6894962B1 (en) * | 1998-10-21 | 2005-05-17 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium with sector address information |
-
2000
- 2000-11-10 EP EP00124632A patent/EP1205918A1/en not_active Withdrawn
-
2001
- 2001-10-12 TW TW090125158A patent/TW577045B/en active
- 2001-10-29 US US10/416,263 patent/US7158471B2/en not_active Expired - Fee Related
- 2001-10-29 JP JP2002541674A patent/JP3972817B2/en not_active Expired - Fee Related
- 2001-10-29 CN CNB018185355A patent/CN1229786C/en not_active Expired - Fee Related
- 2001-10-29 EP EP01989431A patent/EP1332495B1/en not_active Expired - Lifetime
- 2001-10-29 DE DE60138128T patent/DE60138128D1/en not_active Expired - Lifetime
- 2001-10-29 KR KR10-2003-7005239A patent/KR20030044000A/en active IP Right Grant
- 2001-10-29 WO PCT/EP2001/012498 patent/WO2002039439A2/en active Application Filing
- 2001-10-29 AU AU2002227900A patent/AU2002227900A1/en not_active Abandoned
-
2006
- 2006-11-09 US US11/595,063 patent/US20070053266A1/en not_active Abandoned
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5414451A (en) * | 1991-10-11 | 1995-05-09 | Hitachi, Ltd. | Three-dimensional recording and reproducing apparatus |
US5905702A (en) * | 1992-04-10 | 1999-05-18 | Canon Kabushiki Kaisha | Optical information recording apparatus and method capable of coping with a plurality of card-like recording mediums of different reflectances |
US5627816A (en) * | 1992-11-26 | 1997-05-06 | Matsushita Electric Industrial Co., Ltd. | Multilayer optical disk and apparatus |
US5559784A (en) * | 1993-03-26 | 1996-09-24 | Fuji Xerox Co., Ltd. | Multi-layer optical information detection by two laser beam and optical multilayer recording medium |
US5373499A (en) * | 1993-07-22 | 1994-12-13 | International Business Machines Corporation | Multilayer optical disk and system having multiple optical paths include identical total disk substrate thickness |
US6434095B1 (en) * | 1995-04-07 | 2002-08-13 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium, manufacturing method therefor, manufacturing apparatus therefor, and optical information recording and reproducing apparatus |
US6101157A (en) * | 1997-06-27 | 2000-08-08 | Pioneer Electronic Corporation | Apparatus and method for focus control of read light irradiated on a recording surface |
US6456584B1 (en) * | 1998-05-15 | 2002-09-24 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium comprising a first layer having a phase that is reversibly changeable and a second information layer having a phase that is reversibly changeable |
US6894962B1 (en) * | 1998-10-21 | 2005-05-17 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium with sector address information |
US6511788B1 (en) * | 1999-02-12 | 2003-01-28 | Sony Corporation | Multi-layered optical disc |
US20020051414A1 (en) * | 2000-10-23 | 2002-05-02 | Pioneer Corporation And Tohoku Pioneer Corporation | Multi-layer information recording medium and recording apparatus for the same |
Also Published As
Publication number | Publication date |
---|---|
EP1332495A2 (en) | 2003-08-06 |
EP1205918A1 (en) | 2002-05-15 |
CN1531725A (en) | 2004-09-22 |
EP1332495B1 (en) | 2009-03-25 |
WO2002039439A3 (en) | 2002-08-22 |
WO2002039439A2 (en) | 2002-05-16 |
US20040032816A1 (en) | 2004-02-19 |
CN1229786C (en) | 2005-11-30 |
KR20030044000A (en) | 2003-06-02 |
DE60138128D1 (en) | 2009-05-07 |
JP3972817B2 (en) | 2007-09-05 |
US7158471B2 (en) | 2007-01-02 |
JP2004530238A (en) | 2004-09-30 |
AU2002227900A1 (en) | 2002-05-21 |
TW577045B (en) | 2004-02-21 |
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