US20080219126A1

Movatterモバイル変換

Info

Publication number: US20080219126A1
Application number: US12/120,348
Authority: US
Inventors: Motoshi Ito; Takashi Ishida; Hiroshi Ueda; Yoshikazu Yamamoto; Mamoru Shoji
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-01-22
Filing date: 2008-05-14
Publication date: 2008-09-11
Also published as: EP1622131B1; KR20100101191A; MXPA04007058A; EP2224438A2; DE60326999D1; CN101281768A; KR101010878B1; EP2224438B1; CN101281770B; EP2075794B1; EP2075794A1; EP1329880A2; KR101121968B1; EP1329880A3; KR101121972B1; KR20110026536A; CN101281771A; KR20080051187A; KR20110122768A; EP2224438A3

Abstract

A multi-layered information recording medium including a plurality of recording layers, the multi-layered information recording medium comprising: a user data area for recording user data; and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein a first spare area of the plurality of spare areas is positioned so as to be contiguous to a first user data area of a first recording layer, a second spare area of the plurality of spare areas is positioned so as to be contiguous to a second user data area of a second recording layer, and the first spare area and the second spare area are positioned approximately at the same radial position on the multi-layered information recording medium.

Description

This application is a continuation application of U.S. patent application Ser. No. 11/566,717 filed on Dec. 5, 2006, which claims priority to U.S. application Ser. No. 10/338,430 filed Jan. 8, 2003, now U.S. Pat. No. 7,184,377 issued Feb. 27, 2007, the entire disclosures of which are incorporated herein by reference, and is related to co-pending sibling U.S. applications, Attorney Docket No. OKUDP0181USB (U.S. application Ser. No. ______), OKUDP0181USC (U.S. application Ser. No. ______), OKUDP0181USD (U.S. application Ser. No. ______) and OKUDP0181USE (U.S. application Ser. No. ______), all filed on May 14, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multi-layered information recording medium including at least two recording layers, a recording apparatus for use with the multi-layered information recording medium, and a recording method for recording information in the multi-layered information recording medium.

2. Description of the Related Art

A typical information recording medium which has a sector structure is an optical disc. In recent years, AV data, such as audio data, video data, and the like, has been digitalized, and accordingly, an optical disc having a higher recording density and larger capacity has been demanded. Providing a plurality of recording layers is useful in increasing the capacity of a disc. For example, the capacity of a read-only DVD has been increased about two times by providing two recording layers to the DVD.

FIG. 1 shows a structure of a typicaloptical disc medium1 including atrack2 andsectors3. Theoptical disc medium1 includes atrack2 turned multiple times in a spiral arrangement. Thetrack2 is divided into a large number ofsmall sectors3. Regions formed on thedisc medium1 are roughly classified into a lead-inzone4, auser data area8 and a lead-outzone6. Recording or reproduction of user data is performed on theuser data area8. The lead-inzone4 and the lead-outzone6 are provided as margins such that an optical head (not shown) can appropriately follow a track even if overrunning of the optical head occurs when the optical head accesses an end portion of theuser data area8. The lead-inzone4 includes a disc information zone which stores parameters necessary for accessing thedisc medium1. Physical sector numbers (hereinafter, abbreviated as “PSN(s)”) are assigned to thesectors3 in order to identify therespective sectors3. Further, consecutive logical sector numbers (hereinafter, abbreviated as “LSN(s)”) which start with zero are assigned to thesectors3 such that a superior apparatus (not shown) such as a host computer identifies therespective sectors3.

FIG. 2 illustrates a principle of reproduction of data from a read-onlyoptical disc30 having two recording layers. Herein, production of the read-onlyoptical disc30 ofFIG. 2 is briefly described. In the first place, grooves are formed onsubstrates31 and32 so as to form spiral tracks. Over the grooved surfaces of thesubstrates31 and32, recordinglayers33 and34 are attached so as to cover the grooved surfaces. Thesubstrates31 and32 are combined so as to sandwich transparent light-curable resin35 between therecording layers33 and34, thereby obtaining a single read-onlyoptical disc30. In this specification, for convenience of description, inFIG. 2, a recording layer34 closer to theincoming laser light38 is referred to as a first recording layer34; whereas theother recording layer33 is referred to as asecond recording layer33. The thickness and composition of the first recording layer34 are calibrated such that the first recording layer34 reflects a half of theincoming laser light38 and transmits the other half of theincoming laser light38. The thickness and composition of thesecond recording layer33 are calibrated such that thesecond recording layer33 reflects all of theincoming laser light38. Anobjective lens37 forgathering thelaser light38 is moved toward or away from theoptical disc30 such that the convergence point (beam spot)36 of thelaser light38 is placed on the first recording layer34 or thesecond recording layer33.

FIGS. 3A,3B,3C and3D show tracks of two

recording layers

41 and42 of a read-only DVD, which are called parallel paths, and the reproduction direction and sector numbers.FIG. 3A shows a spiral groove pattern of thesecond recording layer42.FIG. 3B shows a spiral groove pattern of thefirst recording layer41.FIG. 3C shows the reproduction direction inuser data areas8 provided on the

recording layers

41 and42.FIG. 3D shows sector numbers assigned to the

recording layers

41 and42.

Now, consider the read-only DVD disc is rotated clockwise when it is viewed from the back face side of the disc in the direction along which laser light comes onto the disc, i.e., when it is viewed from the back side of the sheets ofFIGS. 3A and 3B. In this case, the laser light moves along thetrack2 from the inner circumference side to the outer circumference side of the

recording layers

41 and42. In the case where user data is sequentially reproduced along the reproduction direction shown inFIG. 3C, reproduction is first performed from the innermost circumference position to the outermost circumference position of theuser data area8 of thefirst recording layer41. Then, reproduction is performed from the innermost circumference position to the outermost circumference position of theuser data area8 of thesecond recording layer42. Theuser data areas8 of the first and

second recording layers

41 and42 are sandwiched by the lead-inzone4 and the lead-outzone6 such that an optical head can appropriately follow thetrack2 even if overrunning of the optical head occurs. As shown inFIG. 3D, the PSNs and LSNs of each of the

recording layers

41 and42 are incrementally assigned along the reproduction direction. The PSNs do not necessarily need to start with zero in view of convenience of disc formation. Further, the PSNs do not necessarily need to be continuously assigned between the first andsecond recording layers41 and42 (for example, a value corresponding to the layer number may be provided at the first position of each sector number). As LSNs, consecutive numbers which start with zero are assigned to all of theuser data areas8 included in the optical disc. That is, in theuser data area8 of thefirst recording layer41, the LSN at the innermost circumference position is zero, and incrementally increases toward the outermost circumference. The LSN at the innermost circumference position of theuser data area8 of thesecond recording layer42 is a number obtained by adding 1 to the maximum LSN of thefirst recording layer41. The LSN of thesecond recording layer42 also increases in an incremental manner toward the outermost circumference.

FIGS. 4A,4B,4C and4D show tracks of two

recording layers

43 and44 of a read-only DVD, which is called an opposite path arrangement, and the reproduction direction and sector numbers.FIG. 4A shows a spiral groove pattern of thesecond recording layer44.FIG. 4B shows a spiral groove pattern of thefirst recording layer43.FIG. 4C shows the reproduction direction inuser data areas8 provided on the recording layers43 and44.FIG. 4D shows sector numbers assigned to the recording layers43 and44.

Now, consider the read-only DVD disc is rotated clockwise when it is viewed from the back face side of the disc in the direction along which laser light comes onto the disc, i.e., when it is viewed from the back side of the sheets ofFIGS. 4A and 4B. In this case, the laser light moves along thetrack2 from the inner circumference side to the outer circumference side in thefirst recording layer43, but from the outer circumference side to the inner circumference side in thesecond recording layer44. In the case where user data is sequentially reproduced along the reproduction direction shown inFIG. 4C, reproduction is first performed from the innermost circumference position to the outermost circumference position of theuser data area8 of thefirst recording layer43. Then, reproduction is performed from the outermost circumference position to the innermost circumference position of theuser data area8 of thesecond recording layer44. Theuser data area8 of thefirst recording layer43 is sandwiched by the lead-inzone4 and amiddle zone7 such that an optical head can appropriately follow thetrack2 even if overrunning of the optical head occurs. Theuser data area8 of thesecond recording layer44 is sandwiched by themiddle zone7 and the lead-outzone6. The function of themiddle zone7 is the same as that of the lead-outzone6. As shown inFIG. 4D, the PSNs and LSNs of each of the recording layers43 and44 are incrementally assigned along the reproduction direction as in the above-described parallel paths, except that the relationship between the sector numbers and the radial direction because the spiral direction of thetrack2 of thesecond recording layer44 is inverse to the spiral direction of thetrack2 of thefirst recording layer43. In theuser data area8 of thefirst recording layer43, the LSN is zero at the innermost circumference position, and increases incrementally toward the outer circumference side. The LSN at the outermost circumference position in theuser data area8 of thesecond recording layer44 is a number obtained by adding 1 to the maximum LSN in theuser data area8 of thefirst recording layer43, and increases in an incremental manner toward the innermost circumference.

Above, read-only optical discs have been described. Now, features specific to a rewritable optical disc are described. Such features result from the fact that requirements on a margin for a recording operation are more severe than that for a reproduction operation.

FIG. 5 shows a region layout of therecording layer45 included in a DVD-RAM which is a rewritable DVD disc. The DVD-RAM has only one recording layer (i.e., recording layer45). As shown inFIG. 5, the lead-inzone4 of therecording layer45 includes adisc information zone10, an OPC (Optimum Power Calibration)region11, and adefect management region12. The lead-outzone6 includes anotherdefect management region12.Spare areas13 are provided between the lead-inregion4 and theuser data area8, and between theuser data area8 and the lead-outzone6, respectively.

Thedisc information zone10 stores disc information regarding parameters necessary for recording/reproduction of data of the optical disc or data format of the optical disc. Thedisc information zone10 is also included in a read-only optical disc, but thedisc information zone10 of the read-only optical disc includes nothing important other than a format identifier used for identifying the optical disc. On the other hand, in a rewritable optical disc, specific recommended values for the characteristics of the laser light used for recording, such as the laser power, pulse width, and the like, are stored for each generated mark width. Thedisc information zone10 is a read-only region in which information is typically written in at the time of production of the disc. In a DVD-RAM, pits are formed in the disc surface as in a DVD-ROM. (There is a recording principle different from such a “pit” recording principle. For example, in a CD-RW, information is superposed on a meander region (called a “wobble” region) of a groove.)

TheOPC region11 is provided for optimally calibrating the recording power of laser light. A disc manufacturer stores recommended laser parameters for a recording operation in thedisc information zone10. However, a laser element used by the disc manufacturer for obtaining the recommended values is different from a laser element incorporated in an optical disc drive apparatus, in respect to laser characteristics, such as the wavelength, the rising time of the laser power, and the like. Further, even a laser element of the same optical disc drive, the laser characteristics thereof vary because of a variation of the ambient temperature or deterioration which occurs over time. Thus, in an actual case, test recording is performed on theOPC region11 while increasingly and decreasingly changing the laser parameters stored in thedisc information zone10, such as the power value and the like, so as to obtain an optimum recording power.

Thedefect management region12 and thespare areas13 are provided for defect management i.e., provided for replacing a sector of theuser data area8 in which recording/reproduction cannot be appropriately performed (referred to as a “defect sector”) with another well-conditioned (i.e., sufficiently usable) sector. In a rewritable single-layer optical disc, such as a 90 mm magneto-optical disc defined in the ISO/IEC10090 specifications, or the like, defect management is generally performed.

Thespare areas13 include a sector prepared as a replacement for a defect sector (referred to as a spare sector). A sector which was employed in place of a defect sector is referred to as a replacement sector. In a DVD-RAM, thespare areas13 are placed at two positions, such that one is at the inner circumference side and the other is at the outer circumference side. The size of thespare area13 at the outer circumference side is extendable such that an increase of defect sectors which goes beyond expectation can be handled.

Thedefect management region12 includes: a disc definition structure (DDS)20 having a format designed for defect management, which includes the size of thespare area13 and the position where thespare area13 is placed; and a defect list (DL)21 which lists the positions of defect sectors and the positions of replacement sectors. In view of robustness, many discs are designed based on a specification such that each of the inner circumference portion and outer circumference portion of a disc has onedefect management region12, and eachdefect management region12 duplicatively stores the same content, i.e., thedefect management regions12 of the disc have the four same contents in total. Alternatively, according to the specification for a 650 MB phase change optical disc (PD), a spare area is provided in thedefect management region12, and when a sector storing aDL21 changes into a defect sector, theDL21 is stored in a sector of the spare area.

The above structure is provided for a system including an optical disc drive in order to achieve data reliability on the same level as that of a read-only optical disc in a rewritable optical disc under a condition that margins for physical characteristics are severe in a recording operation rather than a reproduction operation.

Although there are read-only information recording mediums having a plurality of recording layers, all existing rewritable information recording medium have only a single recording layer. The above-described defect management for a rewritable information recording medium is directed to management of only one recording layer. There is no document which discloses defect management in an information recording medium having a plurality of recording layers. If defect management is performed independently in each recording layer, a defect sector in a certain recording layer may not be replaced even when there is no more spare area in the certain recording layer but another recording layer still has an available spare area. Further, in the case where tracks of a disc is arranged in an opposite path arrangement (seeFIGS. 4A through 4D), if a spare area is assigned arbitrarily in each recording layer, the radial position of the first recording layer and the radial position of the second recording layer deviate from each other at a transition position where laser light transits from the first recording layer to the second recording layer. In such a case, the access speed decreases.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a multi-layered information recording medium including a plurality of recording layers, the multi-layered information recording medium comprising: a user data area for recording user data; and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein the plurality of recording layers include a first recording layer and a second recording layer positioned contiguous to each other, the first recording layer includes a first user data area which is a portion of the user data area, and a first spare area which is one of the plurality of spare areas, the second recording layer includes a second user data area which is another portion of the user data area, and a second spare area which is another one of the plurality of spare areas, the first spare area is positioned so as to be contiguous to the first user data area, the second spare area is positioned so as to be contiguous to the second user data area, and the first spare area and the second spare area are positioned approximately at the same radial position on the multi-layered information recording medium.

In one embodiment of the present invention, logical addresses are assigned to the first user data area along a circumference direction from an inner circumference side to an outer circumference side of the multi-layered information recording medium; logical addresses are assigned to the second user data area along a circumference direction from the outer circumference side to the inner circumference side of the multi-layered information recording medium; the logical addresses assigned to the first user data area and the logical addresses assigned to the second user data area are in series; the first spare area is positioned so as to be contiguous to a sector to which a maximum logical address is assigned among a plurality of sectors included in the first user data area; and the second spare area is positioned so as to be contiguous to a sector to which a minimum logical address is assigned among a plurality of sectors included in the second user data area.

According to another aspect of the present invention, there is provided a multi-layered information recording medium including a plurality of recording layers, the multi-layered information recording medium includes: a user data area for recording user data; and a plurality of OPC regions provided for calibrating a recording power of laser light, wherein each of the plurality of recording layers includes a corresponding one of the plurality of OPC regions.

In one embodiment of the present invention, the multi-layered information recording medium further comprises a calibration result storage region for storing a result of calibration of the recording power of the laser light, wherein the calibration result storage region is provided in at least a reference layer selected from the plurality of recording layers.

In another embodiment of the present invention, the plurality of recording layers include a first recording layer and a second recording layer positioned contiguous to each other; the first recording layer includes a first user data area which is a portion of the user data area; the second recording layer includes a second user data area which is another portion of the user data area; logical addresses are assigned to the first user data area along a circumference direction from an inner circumference side to an outer circumference side of the multi-layered information recording medium; and logical addresses are assigned to the second user data area along a circumference direction from the outer circumference side to the inner circumference side of the multi-layered information recording medium.

In still another embodiment of the present invention, the plurality of recording layers include a first recording layer and a second recording layer positioned contiguous to each other; the first recording layer includes a first user data area which is a portion of the user data area; the second recording layer includes a second user data area which is another portion of the user data area; logical addresses are assigned to the first user data area along a circumference direction from an inner circumference side to an outer circumference side of the multi-layered information recording medium; and logical addresses are assigned to the second user data area along a circumference direction from the inner circumference side to the outer circumference side of the multi-layered information recording medium.

According to still another aspect of the present invention, there is provided a multi-layered information recording medium including a plurality of recording layers, the multi-layered information recording medium comprising: a user data area for recording user data; and at least one spare area including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in replacement of the at least one defect region, wherein the user data area includes a plurality of sectors, a logical address is assigned to each of the plurality of sectors, and one of the at least one spare area is positioned so as to be contiguous to a sector to which a maximum logical address is assigned among the plurality of sectors included in the user data area, and said spare area is expandable.

In one embodiment of the present invention, the spare area positioned contiguous to the sector to which the maximum logical address is assigned is expandable in a direction from the spare area toward the user data area.

According to still another aspect of the present invention, there is provided a recording apparatus for recording information in a multi-layered information recording medium including a plurality of recording layers, wherein: the multi-layered information recording medium includes a user data area for recording user data, and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein the plurality of spare areas are provided in at least two recording layers of the plurality of recording layers; the recording apparatus includes an optical head section capable of optically writing the information in the multi-layered information recording medium from one surface of the multi-layered information recording medium, and a control section for controlling execution of a defect management process using the optical head section; and the defect management process includes steps of finding at least one available spare area among the plurality of spare areas, determining whether or not the user data area includes a defect region, if it is determined that the user data area includes a defect region, selecting a spare area whose distance from the defect region is shortest among the at least one spare area found, and replacing the defect region with a replacement region included in the selected spare area.

According to still another aspect of the present invention, there is provided a recording apparatus for recording information in a multi-layered information recording medium including a plurality of recording layers, wherein: the multi-layered information recording medium includes a user data area for recording user data, and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein the plurality of spare areas are provided in at least two recording layers of the plurality of recording layers, and each of the plurality of recording layers includes a portion of the user data area; the recording apparatus includes an optical head section capable of optically writing the information in the multi-layered information recording medium from one surface of the multi-layered information recording medium, and a control section for controlling execution of a defect management process using the optical head section; and the defect management process includes steps of finding at least one available spare area among the plurality of spare areas, determining whether or not the user data area includes a defect region, if it is determined that the user data area includes a defect region, determining whether or not a recording layer, in which an area including the defect region which is a portion of the user data area exists, includes at least one of the at least one spare area found, if it is determined that the recording layer, in which the area including the defect region exists, includes none of the at least one spare area found, selecting a spare area whose distance from the defect region is shortest among the at least one spare area found, and replacing the defect region with a replacement region included in the selected spare area.

According to still another aspect of the present invention, there is provided a recording method for recording information in a multi-layered information recording medium including a plurality of recording layers, wherein: the multi-layered information recording medium includes a user data area for recording user data, and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein the plurality of spare areas are provided in at least two recording layers of the plurality of recording layers; and the recording method includes steps of finding at least one available spare area among the plurality of spare areas, determining whether or not the user data area includes a defect region, if it is determined that the user data area includes a defect region, selecting a spare area whose distance from the defect region is shortest among the at least one spare area found, and replacing the defect region with a replacement region included in the selected spare area.

According to still another aspect of the present invention, there is provided a recording method for recording information in a multi-layered information recording medium including a plurality of recording layers, wherein: the multi-layered information recording medium includes a user data area for recording user data, and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein the plurality of spare areas are provided in at least two recording layers of the plurality of recording layers, and each of the plurality of recording layers includes a portion of the user data area; and the recording method includes steps of finding at least one available spare area among the plurality of spare areas, determining whether or not the user data area includes a defect region, if it is determined that the user data area includes a defect region, determining whether or not a recording layer, in which an area including the defect region which is a portion of the user data area exists, includes at least one of the at least one spare area found, if it is determined that the recording layer, in which the area including the defect region exists, includes none of the at least one spare area found, selecting a spare area whose distance from the defect region is shortest among the at least one spare area found, and replacing the defect region with a replacement region included in the selected spare area.

Thus, the invention described herein makes possible the advantages of providing: (1) a multi-layered information recording medium wherein placement of spare areas in a plurality of recording layers is designed such that the spare areas are used efficiently and access characteristics are improved; and (2) an information recording method, an information reproduction method, an information recording apparatus and an information reproduction apparatus for use with the above multi-layered information recording medium.

These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a structure of a track and sectors in a commonly employed optical disc.

FIG. 2 illustrates a reproduction principle for an optical disc having two recording layers.

FIG. 3A shows a groove pattern in a second recording layer in a parallel path of a DVD disc.

FIG. 3B shows a groove pattern in a first recording layer in a parallel path of a DVD disc.

FIG. 3C illustrates a recording/reproduction direction in a parallel path of a DVD disc.

FIG. 3D illustrates assignment of sector numbers in a parallel path of a DVD disc.

FIG. 4A shows a groove pattern in a second recording layer in an opposite path of a DVD disc.

FIG. 4B shows a groove pattern in a first recording layer in an opposite path of a DVD disc.

FIG. 4C illustrates a recording/reproduction direction in an opposite path of a DVD disc.

FIG. 4D illustrates assignment of sector numbers in an opposite path of a DVD disc.

FIG. 5 shows a region layout in a DVD-RAM.

FIG. 6 shows a region layout in a multi-layered information recording medium according toembodiment 1 of the present invention.

FIG. 7 shows a data structure of aDDS20 according toembodiment 1 of the present invention.

FIG. 8 shows a sparefull flag group208 according toembodiment 1 of the present invention.

FIG. 9 shows a data structure of aDL21 according toembodiment 1 of the present invention.

FIG. 10 illustrates assignment of sector numbers inembodiment 1 of the present invention.

FIG. 11A shows a layout of a recording layer included in an information recording medium having a single recording layer.

FIG. 11B shows a layout of recording layers included in a multi-layered information recording medium according toembodiment 2 of the present invention.

FIG. 11C shows a variation of the layout of recording layers shown inFIG. 11B.

FIG. 12 shows a region layout of a multi-layered information recording medium according toembodiment 2 of the present invention.

FIG. 13 shows a data structure of aDDS20 according toembodiment 2 of the present invention.

FIG. 14 shows a sparefull flag group208 according toembodiment 2 of the present invention.

FIG. 15 illustrates assignment of sector numbers inembodiment 2 of the present invention.

FIG. 16 shows a region layout of a multi-layered information recording medium according toembodiment 3 of the present invention.

FIG. 17 illustrates assignment of sector numbers inembodiment 3 of the present invention.

FIG. 18 shows an information recording/reproducingapparatus500 according toembodiment 4 of the present invention.

FIG. 19 is a flowchart for illustrating a procedure of obtaining defect management information according toembodiment 4 of the present invention.

FIG. 20 is a flowchart for illustrating a reproduction procedure of sectors according toembodiment 4 of the present invention, wherein replacement is considered.

FIG. 21 is a flowchart for illustrating a procedure of converting LSNs to PSNs according toembodiment 4 of the present invention.

FIG. 22 is a flowchart for illustrating a procedure of updating defect management information according toembodiment 4 of the present invention.

FIG. 23 is a flowchart for illustrating a recording procedure in sectors according toembodiment 4 of the present invention, wherein replacement is considered.

FIG. 24A is a flowchart for illustrating an assignment procedure of replacement sectors according toembodiment 4 of the present invention.

FIG. 24B shows a variation of the flowchart shown inFIG. 24A.

DESCRIPTION OF THEPREFERRED EMBODIMENTS

Embodiment

1

Hereinafter, a multi-layered information recording medium according toembodiment 1 of the present invention is described with reference to the drawings. In the present invention, the multi-layered information recording medium refers to an information recording medium including two or more recording layers.

FIG. 6 shows a region layout of a multi-layeredinformation recording medium50 according toembodiment 1 of the present invention. The multi-layeredinformation recording medium50 includes two

recording layers

51 and52. The multi-layeredinformation recording medium50 includes auser data area5 for recording user data. In this embodiment of the present invention, the upper recording layer shown inFIG. 6 is referred to as a first recording layer, and the lower recording layer is referred to as a second recording layer. Thefirst recording layer51 includes, from the inner circumference side to the outer circumference side along the recording/reproduction direction, a lead-inzone101, a headspare area105, a firstuser data area15, which is a portion of theuser data area5, an intermediatespare area106, and amiddle region102. Thesecond recording layer52 includes, from the outer circumference side to the inner circumference side along the recording/reproduction direction, amiddle region103, an intermediatespare area106′, a seconduser data area16, which is a portion of theuser data area5, an endspare area107, and a lead-outzone104.

Each of the headspare area105, the intermediatespare area106, the intermediatespare area106′, and the endspare area107 includes at least one replacement region (which is a “spare sector” in the embodiments of the present invention). When theuser data area5 has at least one defect region (which is a “defect sector” in the embodiments of the present invention), the spare sector can be used in place of the defect sector.

The lead-inzone101 includes adisc information zone10, anOPC region11, and adefect management region12. Thedefect management region12 is included in themiddle region102. TheOPC region11 is included in the lead-outzone104. Thedefect management region12 includes aDDS20 andDL21.

Thedisc information zone10 is provided in thefirst recording layer51. Thedisc information zone10 includes recording/reproduction parameters which are recommended for both the first and second recording layers51 and52. With such a structure, the parameters for all the recording layers51 and52 of the multi-layeredinformation recording medium50 can be obtained by simply accessing thefirst recording layer51. Thus, the processing speed can be advantageously increased.

Thedefect management region12 is provided in thefirst recording layer51. Thedefect management region12 includes defect management information about defect management for both the first and second recording layers51 and52. That is, theDDS20 describes information about the headspare area105, the intermediatespare area106, and the endspare area107. Further, theDL21 lists the positions of defect sectors and the positions of replacement sectors which are provided for use in place of the defect sectors for both the first and second recording layers51 and52. With such a structure, all of the information about, defect management of the multi-layeredinformation recording medium50 can be obtained by simply accessing thefirst recording layer51. Thus, the processing speed can be advantageously increased.

The headspare area105 and the intermediatespare area106 are placed contiguous to the both ends of theuser data area15. The intermediatespare area106′ and the endspare area107 are placed contiguous to the both ends of theuser data area16. This arrangement has an advantage such that a sequential recording/reproduction operation along the recording/reproduction direction can be performed at a high-speed as compared with a case where thespare areas105 to107 are placed such that the spare areas divide the

user data area

15 or16 at an intermediate portion. Further, the intermediatespare area106 and the intermediatespare area106′ are placed at the same radial position in the multi-layeredinformation recording medium50. With this arrangement, when the focal position of laser light transits from theuser data area15 of thefirst recording layer51 to theuser data area16 of thesecond recording layer52, the moving distance of the optical head along the radial direction is ideally zero (0), and therefore, a higher accessing speed can be achieved. Herein, the moving distance is ideally zero, i.e., may not be zero, because a deviation may occur when thefirst recording layer51 and thesecond recording layer52 are combined, or the focal position of laser light deviates to an amount corresponding to the eccentricity of the disc during the switching of the focal position of the laser light, and in such a case, a slight movement of the laser light along the radial direction is necessary.

TheOPC region11 provided for calibrating the recording power of the laser light is provided in both thefirst recording layer51 and thesecond recording layer52. This is because one of the recording layers is translucent, whereas the thickness of the other recording layer is calibrated so as to reflect all of the laser light, and accordingly, the recording characteristics are different for each recoding layer. Thus, theOPC region11 is provided in each of thefirst recording layer51 and thesecond recording layer52 so that calibration of the recording power of the laser light can be performed independently in each recording layer.

It is desirable that storage regions for control information other than thedisc information zone10 and thedefect management region12, such as a calibrationresult storage region14 for storing the calibration result for the recording power of the laser light, are provided in thefirst recording layer51 in view of the processing speed as described above.

Each of the sizes of the headspare area105, the intermediatespare area106, and the endspare area107 may be zero. For example, in the case where the sizes of the headspare area105 and the intermediatespare area106 are not zero, and the size of the endspare area107 is zero, the above described advantages of the present invention can be achieved.

FIG. 7 shows the data structure of theDDS20 according toembodiment 1 of the present invention. The data of theDDS20 includes aDDS identifier201, aLSN0 position202, aheadspare area size203, and an intermediatespare area203, an intermediatedspare area size204, an endspare area size205, a first-layer end LSN206, a second-layer end LSN207, and a sparefull flag group208. TheDDS identifier201 indicates that this data structure is DDS. TheLSN0 position202 represents the PSN (i.e., physical address) of a sector whose LSN (i.e., logical address) is 0. The headspare area size203 represents the number of sectors in the headspare area105. The intermediatespare area size204 represents the number of sectors in the intermediatespare area106. The endspare area size205 represents the number of sectors in the endspare area107. The first-layer end LSN206 represents the LSN assigned to the last sector in theuser data area15 of thefirst recording layer51. The first-layer end LSN206 is identical to the number of sectors in theuser data area15. The second-layer end LSN207 represents the LSN assigned to the last sector in theuser data area16 of thesecond recording layer52. The second-layer end LSN207 is equal to a value obtained by adding the number of sectors in theuser data area15 to the number of sectors in theuser data area16. The sparefull flag group208 is a group of flags which represent whether or not there is an available spare sector in thespare areas105 to107.

FIG. 8 shows an example of the sparefull flag group208. A head spare areafull flag221 corresponds to the headspare area105. A first-layer intermediate spare area full flag222 corresponds to the intermediatespare area106. A second-layer intermediate spare area full flag223 corresponds to the intermediatespare area106′. A second-layer end spare area full flag224 corresponds to the endspare area107. The present invention is not limited to this flag arrangement so long as the sparefull flag group208 includes flags corresponding to thespare areas105 to107.

FIG. 9 shows the data structure of theDL21 according toembodiment 1 of the present invention. The data of theDL21 includes aDL identifier301, aDL entry number302, and 0 (zero) ormore DL entries303. TheDL identifier301 indicates that this data structure is DL. TheDL entry number302 represents the number ofDL entries303. TheDL entries303 each include information about adefect sector position304 and areplacement sector position305. The PSN of a defect sector is stored as thedefect sector position304. As thereplacement sector position305, the PSN of a replacement sector is stored. The PSN includes alayer number306 and anintralayer sector number307. Thelayer number306 may be any value so long as the layer can be identified by the value. For example, thelayer number306 of thefirst recording layer51 is 0, and thelayer number306 of thesecond recording layer52 is 1. Theintralayer sector number307 may be any value so long as sectors in a certain recording layer can be identified by the value. For example, theintralayer sector number307 incrementally increases by one every time one sector is passed along the recording/reproduction direction. Even if the relationship between the PSN of a sector in thefirst recording layer51 and the PSN of a sector in thesecond recording layer52 placed at the same radial position is two's complement, the above-described conditions are satisfied as in the opposite paths of a DVD-ROM. For example, consider that the PSN is represented in the 28-bit format, and the PSN of thefirst recording layer51 is within the range of 0000000h to 0FFFFFFh (“h” means that the value is represented by a hexadecimal number). When the PSN of a certain sector in thefirst recording layer51 is 0123450h, the PSN of a corresponding sector in thesecond recording layer52 at the same radial position is FEDCBAFh (see the following steps 1) to 4)):


1)	0	1	2	3	4	5	0	:hexadecimal
								number
2)	0000	0001	0010	0011	0100	0101	0000	:binary number
3)	1111	1110	1101	1100	1011	1010	1111	:bit-inverted
								binary number
4)	F	E	D	C	B	A	F	:hexadecimal
								number

The most significant bit of the PSN of thefirst recording layer51 is always zero, and the most significant bit of the PSN of thesecond recording layer52 is always F. This most significant bit is equal to thelayer number306. In thefirst recording layer51, when the track is followed along the recording/reproduction direction (from the inner circumference side to the outer circumference side), the PSN of the next sector is 0123451h. In thesecond recording layer52, when the track is followed along the recording/reproduction direction (from the outer circumference side to the inner circumference side), the PSN of the next sector is FEDCBB0h. Thesector number307 can be obtained by simply removing the most significant bit (i.e., the layer number306) from the PSN. In thefirst recording layer51, thesector number307 of a current sector is 123450h, and thesector number307 of a next sector is 123451h. In thesecond recording layer52, thesector number307 of a current sector is EDCBAFh, and thesector number307 of a next sector is EDCBB0h.

When theDL21 of the present invention is used, a defect sector can be replaced with a spare sector in a spare area provided in the same recording layer in which the defect sector is included, and moreover, a defect sector can be replaced with a spare sector of a recording layer different from the recording layer in which the defect sector is included. For example, aDL entry303 wherein thedefect sector position304 represents the PSN in thefirst recording layer51, and thereplacement sector position305 represents the PSN in thesecond recording layer52, means that a defect sector in the firstuser data area15 of thefirst recording layer51 was replaced with a spare sector in thesecond recording layer52. If a defect list is formed by DL entries based on which a recording layer cannot be identified, as in the conventional art, replacement processing cannot be successfully performed when the number of defect sectors is greater than the number of spare sectors provided in a recording layer. Thus, according toembodiment 1 of the present invention, defect sectors can be replaced with spare sectors until all the spare sectors of all the recording layers are used. That is, the spare areas can be efficiently used.

FIG. 10 illustrates the assignment of the sector numbers according toembodiment 1 of the present invention. The sector numbers assigned from the inner circumference to the outer circumference in thefirst recording layer51 and then from the outer circumference to the inner circumference in thesecond recording layer52 are arranged horizontally from left to right in the drawing. Thus, from left to right in the drawing, the headspare area105, the firstuser data area15, the intermediatespare area106, the intermediatespare area106′, the seconduser data area16, and the endspare area107 occur in this order. Each of these regions and areas include a plurality of sectors. In thefirst recording layer51, the PSN increases by 1 every time a single sector is passed toward the outer circumference side; whereas in thesecond recording layer52, the PSN increases by 1 every time a single sector is passed toward the inner circumference side. The assignment may be made such that values obtained by removing the layer number (i.e., the most significant bit) from the PSNs of thefirst recording layer51 are in the same numeric range as values obtained by removing the layer number (i.e., the most significant bit) from the PSNs of thesecond recording layer52. (That is, the minimum PSN within the sectors included in the headspare area105 of thefirst recording layer51 is identical to the minimum PSN within the sectors included in the intermediatespare area106′ of thesecond recording layer52 except for the layer number; and the maximum PSN within the sectors included in the intermediatespare area106 of thefirst recording layer51 is identical to the maximum PSN within the sectors included in the endspare area107 of thesecond recording layer52 except for the layer number.) The relationship of the PSN of a sector in thefirst recording layer51 and the PSN of a sector in thesecond recording layer52 placed at the same radial position may be two's complement as in the opposite paths of a DVD-ROM.

The LSNs are assigned only to a plurality of sectors included in theuser data area5. In the firstuser data area15, the LSNs are assigned along the circumference direction of the multi-layeredinformation recording medium50. In the seconduser data area16 also, the LSNs are assigned along the circumference direction of the multi-layeredinformation recording medium50. The LSNs assigned to the firstuser data area15 and the LSNs assigned to the seconduser data area16 are consecutive numbers.

In the firstuser data area15 of thefirst recording layer51, 0 (zero) is assigned to a sector at the innermost circumference position as a LSN. The LSN incrementally increases by 1 every time one sector is passed from the inner circumference side to the outer circumference side. In the seconduser data area16 of thesecond recording layer52, a value obtained by adding 1 to the maximum LSN within the firstuser data area15 of thefirst recording layer51 is assigned to a sector at the outermost circumference position as a LSN. The LSN incrementally increases by 1 every time one sector is passed from the outer circumference side to the inner circumference side. In this way, in the seconduser data area16, the logical addresses (i.e., LSNs) are assigned along a direction opposite to the assignment direction in the firstuser data area15.

The intermediatespare area106 is positioned contiguous to a sector having the maximum logical address (i.e., maximum LSNs) in the firstuser data area15. The intermediatespare area106′ is positioned contiguous to a sector having the minimum logical address (i.e., minimum LSNs) in the seconduser data area16. As described above, the intermediatespare area106 and the intermediatespare area106′ are placed at the same radial position of the multi-layeredinformation recording medium50. Accordingly, the sector having the maximum logical address in the firstuser data area15 and the sector having the minimum logical address in the seconduser data area16 are at the same radial position of the multi-layeredinformation recording medium50. Due to this arrangement, the moving distance of laser light along the radial direction is ideally zero when the focal position of the laser light is switched from the sector having the maximum logical address in the firstuser data area15 to the sector having the minimum logical address in the seconduser data area16.

Even if user data has already been recorded in theuser data area5, the size of the spare areas can be increased. This is explained with reference toFIG. 10. The endspare area107 is placed contiguous to a sector having the maximum LSN in theuser data area5. The endspare area107 can be expanded in a direction from the endspare area107 toward the second user data area16 (i.e., the direction indicated byarrow107′ inFIG. 10).

First, before the endspare area107 is expanded in the direction indicated byarrow107′, user data recorded in a portion of the seconduser data area16 which will be converted to the endspare area107 is transferred to another portion of theuser data area5. Then, the file management information of the transferred user data is modified such that the file management information of the transferred user data (which is one of the information managed by a file system) refers to a sector position to which the user data has been transferred. Next, change of the size of theuser data area5 is reflected in the volume space management information (which is one of the information managed by a file system). Then, in the last step, the size of the endspare area107 is increased. It should be noted that increasing the sizes of the headspare area105 and the intermediate

spare areas

106 and106′ is not practical because, if the sizes of these regions are increased, the assignment of the LSNs to theuser data area5 are changed, and as a result, the file system for managing theuser data area5 using the LSNs would corrupt.

As described above, according toembodiment 1 of the present invention, in a multi-layered information recording medium having two recording layers, continuous accessibility can be improved. Furthermore, a defect sector can be replaced with a spare area in any recording layer, and therefore, the spare areas can be efficiently used. Furthermore, the size of the spare area can be increased so as to prevent lack of spare areas, whereby reliability of data can be improved.

Embodiment 2

Hereinafter, a multi-layered information recording medium according toembodiment 2 of the present invention is described with reference to the drawings.

First, a reference layer which is used as a reference among a plurality of recording layers included in a multi-layered information recording medium is described.FIGS. 11A,11B and11C illustrate a layout of recording layers of an information recording medium according toembodiment 2.FIG. 11A illustrates a layout of layers included in aninformation recording medium53 having asingle recording layer402. InFIG. 11A, theinformation recording medium53 includes atransparent resin401, a totalreflection recording layer402, and asubstrate400 along a direction through which laser light enters theinformation recording medium53. The totalreflection recording layer402 is positioned at depth d from the surface of thetransparent resin401 through which the laser light enters.FIGS. 11B and 11C illustrate layouts of the layers included in

information recording mediums

54 and55 each of which has three

recording layers

402,403 and404. In these layouts, the

translucent recording layers

403 and404 are provided in this order, toward coming laser light, on the totalreflection recording layer402 which is formed on thesubstrate400, such that the

translucent recording layers

403 and404 are sandwiched by thetransparent resin401. In theinformation recording medium54 ofFIG. 11B, the totalreflection recording layer402 is at depth d from the surface of the outermosttransparent resin layer401 through which the laser light enters theinformation recording medium54. In theinformation recording medium55 ofFIG. 11C, thetranslucent recording layer403 is at depth d from the surface of the outermosttransparent resin layer401 through which the laser light enters theinformation recording medium55. This is a typical difference between theinformation recording medium54 and theinformation recording medium55.

In general, an optical head section is designed such that an optimum light spot is obtained at depth d. Herein, a recording layer at depth d is referred to as a reference layer for convenience of explanation. Regions where important information is to be stored, for example, adisc information zone10 and adefect management region12, are desirably positioned in the reference layer. InFIG. 6, thefirst recording layer51, in which thedisc information zone10, thedefect management region12, and the calibrationresult storage region14 are positioned, is a reference layer.

In the description below, the recording layers are referred to as a first recording layer, a second recording layer, a third recording layer, . . . , in the order of largeness of the LSN from the minimum LSN. For example, in theinformation recording medium54 shown inFIG. 11B, the totalreflection recording layer402 is referred to as the first recording layer, thetranslucent recording layer403 is referred to as the second recording layer, and thetranslucent recording layer404 is referred to as the third recording layer. Further, for example, in theinformation recording medium55 illustrated inFIG. 1C, thetranslucent recording layer403 is referred to as the first recording layer, thetranslucent recording layer404 is referred to as the second recording layer, and the totalreflection recording layer402 is referred to as the third recording layer. Thus, the numbering for recording layers does not necessarily depend on the positional relationship of the recording layers. In the above explanation, examples having three recording layers have been described. However, the above explanation similarly applies to any information recording medium including two or more recording layers.

FIG. 12 illustrates a region layout of a multi-layeredinformation recording medium56 according toembodiment 2 of the present invention. The multi-layeredinformation recording medium56 includes three

recording layers

57,58 and59. The multi-layeredinformation recording medium56 includes auser data area5 for recording user data. Thefirst recording layer57 includes a lead-inzone101, a headspare area105, a firstuser data area17 which is a portion of theuser data area5, an intermediatespare area106, and amiddle region102, from the inner circumference side to the outer circumference side, which is the same direction as the recording/reproduction direction. Thesecond recording layer58 includes amiddle region103, an intermediatespare area106′, a seconduser data area18 which is a portion of theuser data area5, an intermediatespare area108, and amiddle region109, from the outer circumference side to the inner circumference side, which is the same direction as the recording/reproduction direction. Thethird recording layer59 includes amiddle region109, an intermediatespare area108′, a thirduser data area19 which is a portion of theuser data area5, an endspare area107, and a lead-outzone104, from the inner circumference side to the outer circumference side, which is the same direction as the recording/reproduction direction. The lead-inzone101 includes adisc information zone10, anOPC region11 and adefect management region12. Themiddle region102 includes adefect management region12. Themiddle region109 includes anOPC region11. Thedefect management region12 includes aDDS20 and aDL21.

Thedisc information zone10 is provided in thefirst recording layer57. Thedisc information zone10 stores recording/reproduction parameters, which are recommended for each of all the recording layers57,58 and59. With such an arrangement, parameters for all the recording layers57,58 and59 of the multi-layeredinformation recording medium56 can be obtained by simply accessing thefirst recording layer57, and thus, the processing speed can be advantageously increased.

Thedefect management region12 is provided in thefirst recording layer57, and includes defect management information for defect management in all the recording layers57,58 and59. That is, theDDS20 describes a headspare area105, intermediate

spare areas

106,106′,108 and108′, and information about the endspare area107. TheDL21 lists the positions of defect sectors in all of the recording layers57,58 and59, and the positions of replacement sectors which are used in place of the defect sectors. With such an arrangement, all information about defect management of the multi-layeredinformation recording medium56 can be obtained by simply accessing thefirst recording layer57, and thus, the processing speed can be advantageously increased.

Each of thespare areas105 to108′ of the recording layers57 to59 is provided at the position contiguous to either end portion of the first to thirduser data areas17 to19. This arrangement is advantageous because sequential recording/reproduction along the recording/reproduction direction can be performed at a high speed, as compared with a case where a spare area is provided at a position such that any of the first to thirduser data areas17 to19 is interrupted by the spare area. Further, the intermediate

spare areas

106 and106′ are provided at the same radial position in an area of the outer circumference side of the recording layers57 and58. With such an arrangement, the moving distance of an optical head section along the radial direction is ideally zero when the focal position of the laser light is switched from the firstuser data area17 to the seconduser data area18. Thus, accessing at a higher speed can be realized. Further, the intermediate

spare areas

108 and108′ are provided at the same radial position in an area of the inner circumference side of the recording layers58 and59. With such an arrangement, the moving distance of an optical head section along the radial direction is ideally zero when the focal position of the laser light is switched from the seconduser data area18 to the thirduser data area19. Thus, the processing speed can be advantageously increased.

Herein, the moving distance is ideally zero, i.e., may not be zero, because a deviation may occur when the recording layers57 to59 are combined, or because the focal position of laser light deviates to an amount corresponding to the eccentricity of the disc during the switching of the focal position of the laser light, and in such a case, a slight movement of the laser light along the radial direction is necessary.

AnOPC region11 is provided in each of all the recording layers57 to59 because the recording layers57 to59 have different recording characteristics. Thus, theOPC region11 is provided in each of the recording layers57 to59 such that calibration of the recording power can be performed separately in any recording layer.

Each of the sizes of the headspare area105, the intermediate

spare areas

106,106′,108 and108′, and the endspare area107 may be zero. For example, in the case where each of the sizes of the headspare area105 and the intermediate

spare areas

106,106′,108 and108′ are not zero, and the size of the endspare area107 is zero, the above described advantages of the present invention can be achieved.

FIG. 13 shows a data structure of aDDS20 according toembodiment 2 of the present invention. TheDDS20 includes aDDS identifier201, arecording layer number209, aLSN0 position202, a headspare area size203, an intermediatespare area size210 at the inner circumference side, an outer circumference side intermediatespare area size211, the endspare area size205, a first layer userdata area size212, an intermediate layer userdata area size213, the end layer userdata area size214, and a sparefull flag group208. InFIG. 13, like elements are indicated by like reference numerals used inembodiment 1, and detailed descriptions thereof are omitted. Therecording layer number209 indicates the total number of recording layers. The inner circumference side intermediatespare area size210 indicates the number of sectors in the intermediate

spare areas

108 and108′ at the inner circumference side. The outer circumference side intermediatespare area size211 indicates the number of sectors in the intermediate

spare areas

106 and106′ at the inner circumference side. The first layer userdata area size212 indicates the number of sectors in the firstuser data area17. The first layer userdata area size212 is equal to the maximum value of the LSN assigned to the firstuser data area17, and therefore, is equal to the first layerlast LSN206 inembodiment 1. The intermediate layer userdata area size213 indicates the number of sectors in the seconduser data area18. The intermediate layer userdata area size213 indicates the number of sectors in the seconduser data area18. The end layer userdata area size214 indicates the number of sectors in the thirduser data area19.

TheDDS20 shown inFIG. 13 can be applied to any multi-layered information recording medium having two or more recording layers. For example, consider that theDDS20 is applied to a multi-layered information recording medium having four recording layers. In this case, therecording layer number209 is four. The intermediate layer userdata area size213 indicates the number of sectors in the user data area of the second recording layer, and also indicates the number of sectors in the user data area of the third recording layer. The end layer userdata area size214 indicates the number of sectors in the user data area of the fourth recording layer.

If the region layout is limited such that the number of sectors included in the intermediate

spare areas

108 and108′ at the inner circumference side is the same as the number of sectors included in the intermediate

spare areas

106 and106′ at the outer circumference side, two information fields, the inner circumference side intermediatespare area size210 and the outer circumference side intermediatespare area size211, can be gathered into a single information field because in such a case thesize210 and thesize211 are always equal. This information field is equivalent to the intermediatespare area size204 described inembodiment 1. If the region layout is limited such that the number of sectors included in the headspare area105 is the same as the number of sectors included in the intermediate

spare areas

108 and108′ at the inner circumference side, the headspare area size203 and the intermediatespare area size210 can be gathered into a single information field. Further, the first layer userdata area size212 and the intermediate layer userdata area size213 may be gathered into a single information field. Thus, information fields which include the identical contents when a certain limitation is made to the region layout can be reduced into a single information field including such a content, and a field obtained by four rules of arithmetic (addition, subtraction, multiplication, and division) may be omitted.

FIG. 14 illustrates an example of the sparefull flag group208. The head spare areafull flag221 corresponds to the headspare area105. The first-layer intermediate spare area full flag222 corresponds to the intermediatespare area106. An intermediate spare area full flag225 for the outer circumference side of the second layer corresponds to the intermediatespare area106′. An intermediate spare area full flag226 for the inner circumference side of the second layer corresponds to the intermediatespare area108. An intermediate spare area full flag227 for the inner circumference side of the third layer corresponds to the intermediatespare area108′. The end spare area full flag224 corresponds to the endspare area107.

The data structure shown inFIG. 9 can also be applied to theDL21 ofembodiment 2 as inembodiment 1. If thelayer number306 is represented in the 4-bit format, 16 recording layers at the most can be expressed. Inembodiment 2 also, defect sectors can be replaced with spare sectors until the spare sectors of all the recording layers are used up. It is clearly appreciated that in such an arrangement, the spare areas can be efficiently used.

FIG. 15 shows assignment of sector numbers according toembodiment 2 of the present invention. The sector numbers assigned from the inner circumference to the outer circumference in thefirst recording layer57, from the outer circumference to the inner circumference in thesecond recording layer58, and then from the inner circumference to the outer circumference in thethird recording layer59, are arranged horizontally from left to right in the drawing. Thus, from left to right in the drawing, the headspare area105, the firstuser data area17, the intermediatespare area106, the intermediatespare area106′, the seconduser data area18, the intermediatespare area108, the intermediatespare area108′, the thirduser data area19, and the endspare area107 occur in this order. In thefirst recording layer57, the PSN increases by 1 every time a single sector is passed toward the outer circumference side. In thesecond recording layer52, the PSN increases by 1 every time a single sector is passed toward the inner circumference side. In thethird recording layer59, the PSN increases by 1 every time a single sector is passed toward the outer circumference side. The assignment directions of LSNs are opposite between contiguous recording layers. The assignment may be made such that values obtained by removing the layer number from the PSNs are in the same numeric range among the first to third recording layers57 to59. Alternatively, a rule of assigning PSNs in the opposite paths of a DVD-ROM may be extended such that the relationship between the values of lower bits of the PSN of a sector in an odd-numbered layer and the values of lower bits of the PSN of a sector in an even-numbered layer at the same radial position may be two's complement. In this case, as values of higher bits of the PSNs, 0 may be assigned to the first and second recording layers, 1 may be assigned to the third and fourth recording layers, and 2 may be assigned to the fifth and sixth recording layers.

The LSNs are assigned only to sectors included in theuser data area5. In the first

user data area

17, 0 is assigned as the LSN of the sector at the innermost circumference position, and the LSN increases by 1 every time a single sector is passed from the inner circumference side to the outer circumference side. In the seconduser data area18, a value obtained by adding 1 to the maximum LSN of the firstuser data area17 is assigned as the LSN of the sector at the outermost circumference position, and the LSN increases by 1 every time a single sector is passed from the outer circumference side to the inner circumference side. In the thirduser data area19, a value obtained by adding 1 to the maximum LSN of the seconduser data area18 is assigned as the LSN of the sector at the innermost circumference position, and the LSN increases by 1 every time a single sector is passed from the inner circumference side to the outer circumference side.

Although a detailed description is herein omitted because it is substantially the same as that provided inembodiment 1, even if user data has already been recorded in theuser data area5 of a multi-layered information recording medium including three or more recording layers, the size of the outermost circumferencespare area107 can be increased.

As described above, according toembodiment 2, continuous accessibility can be improved in a multi-layered information recording medium including two or more recording layers. Furthermore, a defect sector can be replaced with a spare area in any recording layer, and therefore, the spare areas can be efficiently used. Furthermore, the size of the spare area can be increased so as to prevent lack of spare areas, whereby reliability of data can be improved.

Embodiment 3

Hereinafter, a multi-layered information recording medium according toembodiment 3 of the present invention is described with reference to the drawings.

FIG. 16 shows a region layout of a multi-layeredinformation recording medium60 according toembodiment 3 of the present invention. The multi-layeredinformation recording medium60 includes two

recording layers

61 and62. The recording/reproduction direction is the same in both the first and second recording layers61 and62. The multi-layeredinformation recording medium60 includes auser data area5 for recording user data. Thefirst recording layer61 includes, from the inner circumference side to the outer circumference side, a lead-inzone101, a headspare area105, a firstuser data area23, which is a portion of theuser data area5, an intermediatespare area106, and a lead-outzone111. Thesecond recording layer62 includes, from the inner circumference side to the outer circumference side, a lead-inzone110, an intermediatespare area108, a seconduser data area24, which is a portion of theuser data area5, an endspare area107, and a lead-outzone104. The lead-outzone111 includes adefect management region12. The lead-inzone110 includes anOPC region11. InFIG. 16, like elements are indicated by like reference numerals used in

embodiment

1 or 2, and detailed descriptions thereof are omitted.

TheDDS20 ofembodiment 2 shown inFIG. 13 can also be used as the data structure ofembodiment 3. Inembodiment 3, it is not necessary to provide the intermediate layer userdata area size213.

Inembodiment 3, the flag group shown inFIG. 8 is used as the sparefull flag group208 ofembodiment 3.

Inembodiment 3, the data structure shown inFIG. 9 is used as theDL21 ofembodiment 3. Inembodiment 3 also, defect sectors can be replaced with spare sectors until the spare sectors of all the recording layers are used up. It is clearly appreciated that in such an arrangement, the spare areas can be efficiently used.

FIG. 17 shows assignment of sector numbers according toembodiment 3 of the present invention. The sector numbers assigned from the inner circumference to the outer circumference in thefirst recording layer61, and then from the inner circumference to the outer circumference in thesecond recording layer62, are arranged horizontally from left to right in the drawing. Thus, from left to right in the drawing, the headspare area105, the firstuser data area23, the intermediatespare area106, the intermediatespare area108, the seconduser data area24, and the endspare area107 occur in this order. In both thefirst recording layer61 and thesecond recording layer62, the PSN increases by 1 every time a single sector is passed from the inner circumference side to the outer circumference side. The PSNs in the first and second layers at the same radial position are equal except for layer numbers. The LSNs are assigned only to sectors included in theuser data area5. In the first

user data area

23, 0 is assigned as the LSN of the sector at the innermost circumference position, and the LSN increases by 1 every time a single sector is passed from the inner circumference side to the outer circumference side. In the seconduser data area24, a value obtained by adding 1 to the maximum LSN of the firstuser data area23 is assigned as the LSN of the sector at the innermost circumference position, and the LSN increases by 1 every time a single sector is passed from the inner circumference side to the outer circumference side.

It is clear from the comparison made betweenFIGS. 10 and 17, even if the recording/reproduction direction in a recording layer is different between the multi-layeredinformation recording medium50 ofembodiment 1 and the multi-layeredinformation recording medium60 ofembodiment 3, the relationship between assignment of LSNs and disposition of the spare areas is the same. Thus, as described inembodiment 1, even if user data has already been recorded in theuser data area5, the size of spare areas can be increased.

As described above, according toembodiment 3, for multi-layered information recording mediums having two or more recording layers, a common defect management method can be applied to both a multi-layered information recording medium wherein the recording/reproduction direction is the same in all of the recording layers and a multi-layered information recording medium wherein the recording/reproduction direction is alternately inverted for the respective recording layers. Thus, a defect sector can be replaced with a spare area of any recording layer, and therefore, the spare areas can be efficiently used. Furthermore, the size of the spare area can be increased so as to prevent lack of spare areas, whereby reliability of data can be improved.

Embodiment 4

Hereinafter, an embodiment of an information recording/reproducing apparatus, which performs recording/reproduction using the multi-layeredinformation recording medium50 described inembodiment 1, is described with reference to the drawings.

TheCPU514 functions as a control section. TheCPU514 controls the entire operation of the information recording/reproducingapparatus500 via theinternal bus534 according to an incorporated control program. As described below, theoptical head section535 can optically write information in the multi-layeredinformation recording medium50 from one side of the multi-layeredinformation recording medium50. Theoptical head section535 can optically read information from the multi-layeredinformation recording medium50. TheCPU514 controls execution of a defect management process using theoptical head section535 as described below.

In response to the laseremission permitting signal522 output from theCPU514, thelaser driving circuit505 emitslaser light536 onto the multi-layeredinformation recording medium50. The light reflected by the multi-layeredinformation recording medium50 is converted by thelight detector506 to thelight detection signal523. Thelight detection signal523 is subjected to addition/subtraction in thepreamplifier508 so as to generate theservo error signal524 and the analog data signal527. The analog data signal527 is A/D (analog/digital) converted by thebinarization circuit510 to the binarization data signal528. The binarization data signal528 is demodulated by the modulation/demodulation circuit511 to generate the demodulation data signal529. The demodulation data signal529 is converted by theECC circuit512 to the correction data signal530 which does not include any error. The correction data signal530 is stored in abuffer513. Theservo circuit509 outputs theactuator driving signal525 based on theservo error signal524, thereby feeding a servo error back to theactuator504 for focusing control or tracking control of thelens503. An error correction code is added by theECC circuit512 to the storage data signal531 which is an output of data from thebuffer513, so as to generate the encode data signal532. Then, the encode data signal532 is modulated by the modulation/demodulation circuit511 to generate the modulation data signal533. The modulation data signal533 is input to thelaser driving circuit505 so as to modulate the power of laser light.

The information recording/reproducingapparatus500 may be used as a peripheral device of a computer, such as a CD-ROM drive or the like. In such a case, a host interface circuit (not shown) is additionally provided, and data is transmitted between a host computer (not shown) and thebuffer513 through a host interface bus (not shown) such as a SCSI or the like. Alternatively, if the information recording/reproducingapparatus500 concomitantly works as a consumer device such as a CD player or the like, an AV decoder/encoder circuit (not shown) is additionally provided for compressing a moving image or sound or decompressing a compressed moving image or sound in order to transmit data between the host computer and thebuffer513.

In a reproduction operation of the information recording/reproducingapparatus500 according toembodiment 4 of the present invention, it is necessary to provide two processes, a process of obtaining defect management information and a process of reproducing sectors while considering replacement, in order to reproduce information recorded in the multi-layeredinformation recording medium50 including two recording layers to which defect management of the present invention is applied.

In a recording operation of the information recording/reproducingapparatus500 according toembodiment 4 of the present invention, it is necessary to provide, in addition to the above reproduction operation, two processes, a process of updating defect management information and a process of recording sectors while considering replacement, in order to record information in the multi-layeredinformation recording medium50 including two recording layers to which defect management of the present invention is applied.

FIG. 19 shows aflowchart600 for illustrating a procedure of obtaining defect management information inembodiment 4 of the present invention. In this embodiment, thedisc information zone10, in which disc information is stored, and adefect management region12, in which defect management information is stored, are provided in a reference layer.

At the first step of the process of obtaining defect management information, i.e., atstep601, theCPU514 instructs theservo circuit509 to control the focal point of laser light so as to follow a track of a reference layer.

Atstep602, theoptical head section535 reproduces a sector which stores disc information, and theCPU514 confirms parameters and formats which are necessary for recording/reproduction in the multi-layeredinformation recording medium50.

Atstep603, theoptical head section535 reproduces a sector which stores defect management information. The reproduced data is retained in a predetermined place of thebuffer513.

FIG. 20 is aflowchart700 for illustrating a reproduction procedure of sectors according toembodiment 4 of the present invention, wherein replacement is considered. In this reproduction process, assume that defect management information including theDDS20 andDL21 have already been retained in thebuffer513.

At the first step of this reproduction process, i.e., atstep701, theCPU514 converts the LSNs to PSNs (detailed descriptions of this step will be described later with reference toFIG. 21).

Atstep702, theCPU514 refers to the layer number of the PSN to determine whether or not a recording layer in which the focal point of thelaser light536 exists is identical to a recording layer to be reproduced. If identical, the process proceeds to step704: if not, the process proceeds to step703.

Atstep703, theCPU514 instructs theservo circuit509 to let the focal point of thelaser light536 to follow a track of a recording layer to be reproduced.

Atstep704, theoptical head section535 reproduces information recorded in a sector indicated by the PSN obtained atconversion step701.

FIG. 21 is aflowchart800 for illustrating a procedure of converting LSNs to PSNs (i.e., step701 ofFIG. 20) according toembodiment 4 of the present invention. In this embodiment, assume that in the first recording layer, the PSN increases by 1 every time one sector is passed from the inner circumference side to the outer circumference side, while in the second recording layer, the PSN increases by 1 every time one sector is passed from the outer circumference side to the inner circumference side.

At the first step of this replacement process, i.e., atstep801, the LSNs are converted to PSNs without considering a result of replacement of defect sectors indicated in theDL21 with spare areas (i.e., in the same manner as that performed when no defect sector exists). Referring toFIG. 10, if an LSN to be converted is smaller than the total number of sectors included in the firstuser data area15, a corresponding PSN is obtained by calculation of (the minimum PSN of the first user data area15) plus (the LSN). If an LSN to be converted is greater than the total number of sectors included in the firstuser data area15, a corresponding PSN is obtained by calculation of (the minimum PSN of the second user data area16) plus (the LSN) minus (the total number of sectors included in the first user data area15).

Atstep802, theCPU514 refers to theDL entries303 of theDL21 to determine whether or not a sector indicated by the above-calculated PSN has been replaced with a spare sector. If so, the process proceeds to step803; if not, the replacement process ends.

Atstep803, a replacement sector position of theDL entry303, which indicates that the sector having the above PSN has been replaced, is employed as a PSN.

As described above, the information recording/reproducingapparatus500 according toembodiment 4 of the present invention can reproduce information recorded in the multi-layeredinformation recording medium50 having two recording layers to which defect management of the present invention is applied. The reproduction operation of user data which is performed after the focal point of thelaser light536 has been moved to a recording layer to be accessed, is basically the same as the reproduction operation of user data performed for a single-layered information recording medium. Thus, it is clearly appreciated that any user data reproduction procedure for an information recording/reproducing apparatus designed for a single-layered disc can be used.

FIG. 22 is a flow chart for illustrating a procedure of updating defect management information according toembodiment 4 of the present invention. In this embodiment, assume that a formatting process for the multi-layeredinformation recording medium50 includes an initialization process for defect management information and a process of increasing the size of a spare area.

At the first step of this updating process, i.e., atstep901, theCPU514 determines whether or not a necessary formatting process is a process of increasing the size of a spare area. If so, the process proceeds to step902; if not, the process proceeds to step903.

Atstep902, theCPU514 sets a value of the endspare area size205 of the DDS20 (FIG. 7).

Atstep903, theCPU514 sets the respective values of theDDS20 to predetermined values of the device, and sets theDL entry number302 of theDL21 to 0.

Atstep904, theCPU514 determines whether or not the focal point of thelaser light536 is following a track of a reference layer. If so, the process proceeds to step906; if not, the process proceeds to step905.

Atstep905, theCPU514 instructs theservo circuit509 to let the focal point of thelaser light536 to follow the track of the reference layer.

Atstep906, theoptical head section535 records defect management information, including theDDS20 andDL21, in a sector included in thedefect management region12.

FIG. 23 is aflowchart1000 for illustrating a recording procedure in sectors according toembodiment 4 of the present invention, wherein replacement is considered.

At the first step of this recording process, i.e., atstep1001, theCPU514 converts the LSNs to the PSNs according to the procedure shown inFIG. 21.

Atstep1002, theCPU514 refers to the layer number of the PSN to determine whether or not a recording layer in which the focal point of thelaser light536 exists is identical to a recording layer in which information is to be recorded. If identical, the process proceeds to step1004; if not, the process proceeds to step1003.

Atstep1003, theCPU514 instructs theservo circuit509 to let the focal point of thelaser light536 to follow a track of the recording layer in which information is to be recorded.

Atstep1004, information is recorded in a sector indicated by the PSN obtained atconversion step1001.

Atstep1005, theCPU514 controls theoptical head section535 to reproduce the information recorded in the sector, thereby determining whether or not recording of the information in the sector was successful (i.e., whether or not a defect sector exists in the user data area5). If successful, the recording process ends; if not, the process proceeds to step1006.

Atstep1006, theCPU514 assigns a spare sector to a defect sector, thereby replacing the defect sector with the spare sector (details of the process of assigning a spare sector will be described later with reference toFIGS. 24A and 24B).

Atstep1007, it is determined whether or not the process of replacing the defect sector with the spare sector was impossible. If impossible, the recording process ends; if possible, the process returns to step1001.

FIG. 24A is a flowchart for illustrating an assignment procedure of spare sectors according toembodiment 4 of the present invention.

The process of assigning spare sectors includes a process of finding at least one available spare area among a plurality of spare areas included in the multi-layeredinformation recording medium50, and a process of selecting, from the found at least one available spare area, a spare area which is closest to a defect sector. The details of the process of assigning spare sectors are described below with reference toFIG. 24A.

At the first step of the spare sector assignment process, i.e., atstep1101, theCPU514 refers to the spare full flag group208 (FIG. 8) to determine whether or not the multi-layeredinformation recording medium50 has an available spare area. If there is no available spare area, theCPU514 determines that the assignment process is impossible and accordingly terminates the assignment process. If there is an available spare area, the process proceeds to step1102.

Atstep1102, theCPU514 determines whether the radial position of a defect sector is closer to a spare area at the inner circumference side or closer to a spare area at the outer circumference side. If the radial position of the defect sector is closer to a spare area at the inner circumference side, the process proceeds to step1103. If the radial position of the defect sector is closer to a spare area at the outer circumference side, the process proceeds to step1104.

Atstep1103, theCPU514 refers to the sparefull flag group208 to determine whether or not the spare area at the inner circumference side is available. If available, the process proceeds to step1105; if not, the process proceeds to step1106.

Atstep1104, theCPU514 refers to the sparefull flag group208 to determine whether or not the spare area at the outer circumference side is available. If available, the process proceeds to step1106; if not, the process proceeds to step1105.

Atstep1105, theCPU514 refers to the sparefull flag group208 to determine whether or not a spare area which is in a recording layer where the defect sector exists, and which is at the inner circumference side, is available. If available, the process proceeds to step1107; if not, the process proceeds to step1108.

Atstep1106, theCPU514 refers to the sparefull flag group208 to determine whether or not a spare area which is in a recording layer where the defect sector exists, and which is at the outer circumference side, is available. If available, the process proceeds to step1109; if not, the process proceeds to step1110.

Atstep1107, theCPU514 assigns a spare sector included in the spare area which is in a recording layer where the defect sector exists, and which is at the inner circumference side, to the defect sector.

Atstep1108, theCPU514 assigns a spare sector included in a spare area which is in a recording layer different from the recording layer where the defect sector exists, and which is at the inner circumference side, to the defect sector.

Atstep1109, theCPU514 assigns a spare sector included in a spare area which is in a recording layer where the defect sector exists, and which is at the outer circumference side, to the defect sector.

Atstep1110, theCPU514 assigns a spare sector included in a spare area which is in a recording layer different from the recording layer where the defect sector exists, and which is at the outer circumference side, to the defect sector.

In the spare sector assignment procedure shown inFIG. 24A, a spare sector included in a spare area, whose radial distance from the defect sector is shortest, is used as a spare sector. If the radial distance is shorter, the time required for a seek operation, which is accompanied by a movement of the transport table507, becomes shorter. According to the present invention, a different assignment procedure may be used so long as an objective of the present invention, i.e., using a spare sector whose radial distance from a defect sector is shortest as a spare sector, is attained.

FIG. 24B shows aflowchart1120 which illustrates an alternative spare sector assignment process according toembodiment 4 of the present invention.

This alternative assignment process includes the following processes: a process of finding at least one available spare area among a plurality of spare areas included in the multi-layeredinformation recording medium50; a process of determining whether or not at least one of the found available spare areas exists in a recording layer where a portion of theuser data area5 including a defect sector exists; and a process of selecting a spare area which is closest to the defect sector from the at least one found available spare area if it is determined that none of the at least one found spare area exists in the recording layer where the defect sector exists. The details of the process of assigning spare sectors are described below with reference toFIG. 24B.

At the first step of the spare sector assignment process, i.e., atstep1121, theCPU514 refers to the sparefull flag group208 to determine whether or not the multi-layeredinformation recording medium50 has an available spare area. If there is no available spare area, theCPU514 determines that the assignment process is impossible and accordingly terminates the assignment process. If there is an available spare area, the process proceeds to step1122.

Atstep1122, theCPU514 refers to the sparefull flag group208 to determine whether or not a spare area included in a recording layer in which a defect sector exists is available. If available, the process proceeds to step1123; if not, the process proceeds to step1124.

Atstep1123, theCPU514 determines whether the radial position of a defect sector is closer to a spare area at the inner circumference side or closer to a spare area at the outer circumference side. If the radial position of the defect sector is closer to a spare area at the inner circumference side, the process proceeds to step1125. If the radial position of the defect sector is closer to a spare area at the outer circumference side, the process proceeds to step1127.

Atstep1125, theCPU514 refers to the sparefull flag group208 to determine whether or not a spare area residing at the inner circumference side of that recording layer is available. If available, the process proceeds to step1129: if not, the process proceeds to step1131.

Atstep1127, theCPU514 refers to the sparefull flag group208 to determine whether or not a spare area residing at the outer circumference side of that recording layer is available. If available, the process proceeds to step1131: if not, the process proceeds to step1129.

The processes of

steps

1124,1126, and1128 are the same as those of

steps

1123,1125, and1127, respectively, except that a recording layer including a spare area which is to be used is different from a recording layer including the defect sector.

Atstep1129, theCPU514 assigns a spare sector included in the spare area which is in a recording layer where the defect sector exists, and which is at the inner circumference side, to the defect sector.

Atstep1130, theCPU514 assigns a spare sector included in a spare area which is in a recording layer different from the recording layer where the defect sector exists, and which is at the inner circumference side, to the defect sector.

At step1131, theCPU514 assigns a spare sector included in a spare area which is in a recording layer where the defect sector exists, and which is at the outer circumference side, to the defect sector.

Atstep1132, theCPU514 assigns a spare sector included in a spare area which is in a recording layer different from the recording layer where the defect sector exists, and which is at the outer circumference side, to the defect sector.

The spare sector assignment procedure shown inFIG. 24B uses a spare sector in a spare area included in a recording layer in which a defect sector exists so long as such a spare sector is available. By using such a spare sector included in a recording layer in which a defect sector exists, it is not necessary to change different recording parameters for respective recording layers. For example, if in an information recording operation in a recording layer, the recording power is not optimally calibrated for the other recording layers, the assignment procedure shown inFIG. 24B can be performed faster than the assignment procedure shown inFIG. 24A. According to the present invention, a different assignment procedure may be used so long as an objective of the present invention, i.e., using a spare sector in a spare area included in a recording layer in which a defect sector exists so long as such a spare sector is available, is attained.

As described above, the information recording/reproducingapparatus500 according toembodiment 4 of the present invention can record information in the multi-layeredinformation recording medium50 having two recording layers to which defect management of the present invention is applied. The information recording/reproducingapparatus500 can assign a spare sector selected from a spare area included in a recording layer which is different from a recording layer in which a defect sector exists. The information recording/reproducingapparatus500 can perform a process of assigning a spare sector while giving a greater weight to reduction of the seek time as described above with reference toFIG. 24A. Further, the information recording/reproducingapparatus500 can perform a process of assigning a spare sector while giving a greater weight to reduction of the time required for setting the recording power as described above with reference toFIG. 24B. Herein, an operation performed after an optical head section reaches a recording layer to be accessed is basically the same as that performed on a single-layered information recording medium. Thus, it is clearly appreciated that any recording procedure arranged for an information recording/reproducing apparatus designed for a single-layered information recording medium can be used.

The recording operation in the user data area which is performed after the focal point of thelaser light536 has been moved to a recording layer to be accessed, is basically the same as the recording operation of user data performed for a single-layered information recording medium. Thus, it is clearly appreciated that any user data recording procedure for recording in a user data area, which is adapted for an information recording/reproducing apparatus designed for a single-layered disc, can be used.

Although the multi-layeredinformation recording medium50 described inembodiment 1 was used to explainembodiment 4 of the present invention, it is clearly appreciated that the multi-layeredinformation recording medium60 described inembodiment 3 can also be used. Further, it is also clearly appreciated that the multi-layeredinformation recording medium56 described inembodiment 2 can also be used when the conversion processing atstep801 shown inFIG. 21 is applied to three or more recording layers.

Although in the above descriptions of the present invention, reproduction/recording of information and defect management are performed on the units of a sector, it is clearly appreciated that the present invention is applicable even when reproduction/recording of information and defect management is performed on the units of a block which includes a plurality of sectors, or on the units of an ECC block which is, for example, a unit based on which an error correction code of a DVD disc is calculated. For example, in the case where the above operations are performed on the units of an ECC block, a plurality of sectors included in the ECC block in which a defect sector exists are replaced with a plurality of spare sectors, whereby the defect sector is replaced with a spare sector. Such a modified embodiment is made within the spirit and applicable range of the present invention, and any modified embodiment which is readily appreciated by those skilled in the art, falls within the scope of the claims of the present invention.

According to a multi-layered information recording medium of the present invention, one recording layer includes defect management information for all the recording layers. With such an arrangement, the defect management information for all the recording layers can be obtained by simply accessing the one recording layer. Thus, continuous accessibility can be improved.

According to a multi-layered information recording medium of the present invention, a first spare area which is positioned so as to be contiguous to a first user data area and a second spare area which is positioned so as to be contiguous to a second user data area are placed approximately at the same radial position on the multi-layered information recording medium. With this arrangement, when the focal position of laser light transits from the first user data area to the second user data area, the moving distance of an optical head section along the radial direction is ideally zero (0). Thus, continuous accessibility can be improved.

According to a multi-layered information recording medium of the present invention, a detected defect sector can be replaced with a spare area of any recording layer. Thus, spare areas can be efficiently used, and reliability of data can be improved.

According to a multi-layered information recording medium of the present invention, when the number of defect sectors is greater than what is expected, the defect sectors can be replaced with spare sectors by increasing the size of a spare area. Thus, reliability of data can be improved.

According to a multi-layered information recording medium of the present invention, consecutive numbers are assigned as LSNs to the user data areas throughout all the recording layers. With such an arrangement, a common defect management method can be applied to both a multi-layered information recording medium wherein the recording/reproduction direction is the same in all of the recording layers and a multi-layered information recording medium wherein the recording/reproduction direction is alternately inverted for the respective recording layers. Thus, the cost of production and development of the multi-layered information recording medium can be reduced.

According to a multi-layered information recording medium of the present invention, control information regions such as a region for storing recording/reproduction parameters, a region for storing defect management information, or the like, are provided in one recording layer. With such an arrangement, the control information for all the recording layers can be obtained by simply accessing the one recording layer. Thus, continuous accessibility can be improved.

According to a multi-layered information recording medium of the present invention, control information regions are provided in a reference layer. Thus, recording/reproduction operations can be performed in strict conformity with the information in the control information regions.

According to a multi-layered information recording medium of the present invention, every recording layer has its OPC region for calibrating the recording power. With such an arrangement, the recording power can be optimally calibrated for each recording layer.

According to an information reproduction method and information reproduction apparatus of the present invention, information can be reproduced from a multi-layered information recording medium which includes defect management information about a plurality of recording layers.

According to an information recording method and information recording apparatus of the present invention, information can be recorded in a multi-layered information recording medium which includes defect management information about a plurality of recording layers.

According to an information recording method and information recording apparatus of the present invention, a defect sector is replaced with a spare sector included in a spare area which is closer to the defect sector. With such an arrangement, assignment of a spare sector can be performed while giving a greater weight to reduction of the time required for seeking along the radial direction.

According to an information recording method and information recording apparatus of the present invention, a defect sector is replaced with a spare sector included in a spare area residing in a recording layer in which the defect sector exists. With such an arrangement, assignment of a spare sector can be performed while giving a greater weight to reduction of the time required for setting the recording power.

Various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be broadly construed.