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flan** k Cwwwfceifre 



(19) 



Europaisches Patentamt 
European Patent Office 
Office europeen des brevets 



IIIIIIIHHMI 

(11) EP 1 274 081 A2 



(12) 



(43) Date of publication: 

08.01.2003 Bulletin 2003/02 



EUROPEAN PATENT APPLICATION 

(51) lntC!7: G11B 20/18 



(21) Application number: 02014805.2 

(22) Date of filing: 02.07.2002 



(84) Designated Contracting States: 

AT BE BG CH CY CZ DE DK EE ES Fl FR GB GR 
IE IT LI LU MC NL PT SESKTR 

Designated Extension States: 
AL LT LV MK RO SI 

(30) Priority: 02.07.2001 JP 2001201023 

(71) Applicant: NEC CORPORATION 
Tokyo (JP) 



(72) Inventor: Arlyama, Takeo 

Nakahara-ku, Kawasaki-shi, Kanagawa (JP) 

(74) Representative: Glawe, Delfs, Moll & Partner 
Patcntanwalte 
Postfach 26 01 62 
80058 Miirtchen (DE) 



(54) Optical disk device 

(57) The optical disk device according to the present 
invention has a means which reads data of an optical 
disk, the disk being provided in advance with an alter- 
nate area that serves as Its substitute when there exists 
a defect in a data area, and being recorded in advance 
with list information consisting of a plurality of sets each 
□f the set being formed of a position on the disk of the 
data area and an address of the alternate area, and buff- 
ers a data area being defective after correcting it, and a 
means which stores a new alternate list on which is re- 
corded the correspondence relationship between the al- 
ternate area and its buffer destination. The means for 
buffering after correction is equipped with a normal data 
buffer means which refers to the new alternate list and 
buffers data in a normal data area without buffering data 
in a data are a which is defective, an alternate data buff- 
er means which refers to the new alternate list and buff 
ers data in the alternate area in a buffer area shown in 
the new alternate list, and a final data-buffer means 
which buffers an alternate data in a data area which is 
a defect of buffered data obtained by means of the nor- 
mal data buffer means, by combining the buffered data 
obtained by means of the normal data buffer means and 
the buffered data obtained by means ol the alternate da- 
ta buffer means. 



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Printed by Jouve. 750D1 PARIS (PR) 



BNSDOCD: <EP 1274081A2_|_> 



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EP 1 274 081 A2 



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Description 

BACKGROUND OF THE INVENTION 
Field of the Invention 

[0001] The present invention relates to an optical disk 
device, and more particularly to a device for reading da- 
ta from a rewritable optical disk. 

Description of the Prior Art 

[0002] The conventional optical disk device and data 
management method will be described by reference to 
FIG. 4 and FIG. 5. FIG. 4 is a diagram showingthe con- 
ventional system configuration, and FIG. 5 is a diagram 
showing the configuration of conventional optical disk 
and optical disk device. As shown in FIG. 4 and FIG. 6, 
the conventional technology includes an optical disk de- 
vice 1 0 which acquires data of a rewritable optica! disk 
and stores it temporarily (this process will be ref erred to 
as buffering and also as buffer for short) and a host com- 
puter 1 which is the eventual transfer destination of the 
buffered data 

[0003] In the discussion that follows, a pointer within 
a cache of a cached alternate area will be represented 
as a cache pointer. Moreover, a list consisting of a plu- 
rality of sets each of which being formed of an address 
in a defective area and a cache pointer will be repre- 
sented as a cache table 45, and a pointer showing the 
position in a temporary storage memory area 41 of an 
alternate list for the cache table 45 will be represented 
as a table pointer. 

[0004] The optical disk device 1 0 is composed of a 
rewritable optical disk (represented as Rewritable opti- 
cal disk in the drawings) 2 having an alternate list 1 1 , a 
data area 12 and an alternate area 13, a decoders for 
acquiring data from the optical disk 2, a temporary stor- 
age memory area 5, and a control unit 4 for controlling 
data acquisition, construction of a cache table and trans- 
fer of data to the host computer 1 . 
[0005] The decoder3 possesses a function of acquir- 
ing an alternate list 44 from the optical disk 2 for the 
alternate list temporary storage memory area 41 , a func- 
tion of executing buffering for the data area 12, and a 
function of executing caching for a data in the alternate 
area 13. 

[0006] The temporary storage memory area 5 is sub- 
divided into an alternate list temporary storage memory 
area 41 for buffering the alternate list 11 , a data tempo- 
rary storage memory area 43 for buffering data, and a 
cache 42 for caching a data in the alternate area. 
[0007] The operation of the prior art will be described 
by reference to FIG. 5 and FIG. 6. FIG. 5 is a flowchart 
showing data buffering flow according to the conven- 
tional technology. 



1 . Acquisition of the alternate list (S1 and S2) 

[000S] Thecontrolunit4 designates an address of the 
alternate list 1 1 , an acquisition destination pointer of the 

s alternate list, and the acquisition size of the alternate list 
to the decoder 3 (S1), and the decoder 3 acquires, for 
the alternate list acquisition destination pointer of the al- 
ternate list temporary storage memory area 41 , an al- 
ternate list 11 Irom the address of the designated atter- 

10 rate list 11 of the optical disk 2 for the portion corre- 
sponding to the alternate list acquisition size (S2). 

2. Buffering of the data area 1 2 (S23 and S24). 

is [0009] The contra! unit 4 designates the address of 
the data area 1 2, the buffer pointer and the buffer size 
to the decoder 3 (S23), and the decoder 3 executes buff- 
ering to the buffer pointer for the portion corresponding 
to the buffer size, from the address of the designated 

20 data area 12 of the optical disk (S24). 

3. Caching of data in the alternate area 1 3 (S25 to S30) 

[0010] The control unit 4 retrieves within the alternate 

25 list 1 1 to check whether or not there exists a defective 
data in the buffering data (S25). If no defective data ex- 
ists, caching of data in the alternative area 13 will not 
take pi ace (S26) . If there exists o n e, it is checked wheth- 
er or not the alternate area 13 required for caching has 

so already been cached (S27), and only when it is not 
cached yet , th e control u nit 4 desig n ate the address , the 
caching size and the cache pointer of the alternate area 
13 to the decoder 3 (28), and the decoder 3 caches, to 
the cache pointer, data of the alternate area 1 3 for the 

35 portion corresponding to the cache size from the ad- 
dresses of the alternate area 1 3 (S29). 
[001 1] Moreover, with an address of a defective area 
and a buffer pointerwhere Ihe data of the defective area 
is buffered are formed into one set, a cache table 45 is 

40 consiructed from a collection of such sets equal In 
number to the number of buffer pointers present in the 
area of the temporary storage memory area 5 (S3G). 

4. Transfer of buffered data and cached data to the host 
4 5 computer 

(S31 to S34) 

[0012] The control unit 4 checks whether or not the 
so buffered data indicated by the buffer pointer is a defec- 
tive data by referring to the caching table constructed in 
the process 3, in the above (S31). If it is not defective, 
data is transferred from the temporary storage memory 
area 5 to Ihe host computer 1 (S33), and if it is a defec- 
ts five data, an alternate data for the defective data is 
transferred to the host computer 1 from the cache (S32). 
The above processing is repeated for number of times 
corresponding to the buffer size (S34). 



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[0013] As seen from the above processing, when a 
defective data is found in the data buffered from a re- 
writable optical disk, it is necessary to cache alternate 
area data to serve as the substitute. P ho r art for each i n g 
an alternate area can be found in Japanese Patent Ap- 
plications Laid Open, No. 2CQ0-21090, Japanese Pat- 
ent Applications Laid Open, No. 2000-298949, Japa- 
nese Patent Applications Laid Open No. Hei 6-325494, 
Japanese Patent Applcations Laid Open, No. Hei 
8-180598, Japanese Patent Applications Laid Open, 
No. Hei 1-245463, and the [ike. However, a cache is 
needed for implementing caching, which has been a 
problem in the method. 

[0014] That is, a rewritable optical disk has an alter- 
nate list and an alternate area in the unit of tracks, and 
access is made in the unit of tracks, so that according 
to the conventional method, caching algorithm fails to 
act effectively, and an additional caching time and a 
cache are needed for implementing caching. 

BRIEF SUMMARY OF THE INVENTION 

Objects of the Invention 

[0015] It is the object of the present invention to pro- 
vide an optical disk device which obviates the necessity 
for caching an alternate area to be substituted for a de- 
fective area, and realizes a temporary storage memory 
area needed for buffer information before the transfer of 
data to the host computer. 

Summary of the invention 

[0016] The optical diskdevicQ according to this inven- 
tion has a means which reads data of an optical disk, in 
which an alternate area which serves as a substitute 
when a defect occurs in the data area is provided in ad- 
vance, and list information consisting of a plurality of 
sets each of the set being formed of a position on the 
disk of the data area and an address of Its alternate area 
is recorded on the disk in advance, and corrects a de- 
fective data area and buffers it, and a means which 
stores a new alternate list on which is recorded the cor- 
respondence relationship between the alternate area 
and its buffer destination. The buffer means after cor- 
rection comprises a normal data buffer means which re- 
fers to the new alternate list and executes buffer of data 
in a normal data area without executing buffer of data 
in a defective data area, an alternate data buffer means 
which refers to the new alternate list and buffers a data 
In an alternate area in a buffer area shown in the new 
alternate list, and a final data-buffer means which buff- 
ers an alternate data in a data area which is a detect of 
a buffer data obtained by the normal data buffer means 
by combining the buffered data obtained by the normal 
data buffer means and the buffered data obtained by the 
alternate data buffer means. 



BRIEF DESCRIPTION OF THE DRAWINGS 

[0017] The above-mentioned and other objects, fea 
lures and advantages of this invention will become more 
5 apparent by reference to the following detailed descrip- 
tion of the invention taken in conjunction with the accom- 
panying drawings, wherein: 

FIG. 1 Is a block configurations! diagram of an op- 
>o tical disk and an optical disk device accordingto the 
embodiments of this invention; 
FIG. 2 is a flow chart showing the data buffer flow 
of a first embodiment of the invention; 
FIG. 3 is a flow chart showing the data buffer flow 
,B of a second embodiment of the invention; 

FIG. 4 is a diagram showing the system configura- 
tion of the embodiments of this invention and of the 
prior art; 

FIG. 5 is a block configurational diagram of the con- 
20 ventional optical disk and optical disk device; and 
FIG. 6 is a flow chart showing the conventional data 
buffer flew. 

DETAILED DESCRIPTION OF THE INVENTION 

25 

[0018] Referrlngto FIG. 1 and FIG. 4, theoptical disk 
device, program and data management method of the 
optical disk device according to the embodiments of this 
invention will be described. FIG. 1 is a block diagram of 
30 the optical disk device according to the embodiments of 
this invention. It should be mentioned that the system 
configuration of the present embodiments is the same 
as that of FIG. 4. 

[00191 The optica! disk device 10 according to the 

3s present invention is provided in advance with an alter- 
nate area 1 3 which serves as a substitute when the data 
area 12 has a defect, as shown in FIG. 1 and FIG. 4. 
The position of the dala area 12 on the disk and the ad- 
dress in its alternate area 13 are combined into a set, 

to and an alternate list 1 1 In the form of an information list 
consisting of a plurality of such sets is recorded on the 
optical disk2 in advance. The device 10 is provided with 
a data temporary storage memory area 22 in which a 
data area 12 that was found defective at the data read 

is ofthecpticaldisk2isbufferedaftercorrection. Besides, 
it is provided with a new alternate list £4 on which is 
recorded the correspondence relationship between the 
alternate area and its buffer destination. The data tem- 
porary storage memory area 22 is provided with a nor- 

50 mal data buffer section 25 which refers to the new alter- 
nate list 24 and buffers normal data in the data area 12, 
rather than buffer defective data in the data area 12, an 
alternate data buffer section 26 which refers to the new 
alternate list 24 and buffers data in the aiternate area 

55 13 in the buffer area Indicated by the new alternate list 
24, and a final data buffer section 27 which buffers an 
aiternate data in a data area which is a defect of the 
buffered data by the normal data buffer section 25, by 



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combining the buffered data obtained by the normal da- 
ta buffer section 25 and the buffered data obtained by 
the alternate buffer section 26. 
[0020] In the following, the embodiments of this inven- 
tion will be described in more detail. 
[0021] As shown in FIG. 1 and FIG. 4, this invention 
comprises an optical disk device 10 which acquires data 
of a rewritable optical disk 2 and buffers it, and a host 
computer 1 which Is the final transfer destination of the 
buffered data. 

[0D22] The optical disk device 1 0 is constituted by the 
optica! disk 2 which is equipped with the alternate list 
1 1 , the data area 12 and the alternate area 1 3, the de- 
coder 3 for. acquiring data from the optical disk 2, the 
temporary storage memory area 5 for buffering the ac- 
quired data orthe like, and the control unit 4 which con- 
trols data acquisition and its transfer to the host compu- 
ter 1. 

[0023] The decoder 3 has a function of acquiring an 
alternate list 23 from the optical disk 2 to an alternate 
list temporary storage memory area 21 of the temporary 
storage memory area 5, a function of referring to the new 
alternate list 24 which is a list of the alternate area 13 
and the buffer destination, buffering only a normal area 
to the normal buffer section 25 and does not perform 
buffering of fault area, and afunction which refers to the 
new alternate list 24, and buffers the alternate area 13 
to a buffer area indicated in the new alternate list 24 for 
the alternate data buffer section 26. 
[0024] The temporary storage memory area 5 is sub- 
divided into the alternate list temporary storage memory 
area 21 for temporarily storing the alternate list 23, and 
a data temporary storage memory area 22 for buffering 

[0025] Referring to FIG. 1 and FIG. 4, the operation 
of a first embodiment of the invention will be described. 
FIG. 2 is a diagram showing the data buffer flow in the 
first embodiment. The algorithm of the invention will be 
described according to FIG. 1 and FIG. 2. 
[0026] The respective pointers showing the positions 
of the alternate list acquisition destination and the ac- 
quired alternate list, in the alternate list temporary store 
memory area, will be represented as the alternate list 
acquisition destination pointer and the alternate list 
pointer, respectively Besides, assuming that the decod- 
er 3 makes access to the optical disk 2 in the unit of 
sectors, and that the one-sector data of the optical disk 
2 is acquired for one pointer of the temporary store 
memory area 5, the number of sectors of acquired al- 
ternate list 11 will be referred to in the following as the 
alternate list acquisition size. 

1 . 1 Acquisition of the alternate list (S1 and S2) 

[0027] The control unit 4 designates to the decoder 3 
the address of the alternate list 1 1 of the optical disk 2, 
the alternate list acquisition size, and the alternate list 
acquisition destination pointer (S1). The decoder 3 ac- 



'4 081 A2 6 

quires the alternate list 11 forth© alternate list temporary 
storage memory area 21 from the addresses of the des- 
ignated alternate list 11 of the optical disk 2 for the por- 
tion corresponding to the alternate list acquisition size, 
s starting with the alternate list acquisition pointer (S2). 

1 . 2 Construction of table for address of the defective 
area and pointer of buffer destination of the alternate 
area 13 (S3) 

w 

[0028] The position in the data temporary storage 
memory area 22 of the buffer destination of the data ar- 
ea of the optical disk 2 will be represented as the buffer 
pointer, and the number of sectors to be buffered will be 
'5 represented as the buffer size. From the alternate list 

23, the buffer pointer and the buffer size, the control unit 
4 constructs a new alternate list 24 consisting of a plu- 
rality of sets each set formed of the address of the al- 
ternate area and the pointer of ths buffer that buffers its 

20 alternate area at the position represented as the new 
alternate list pointer of the alternate list temporary stor- 
age memoiy area 21. 

1 . 3 Buffering only of normal area in the data area 1 2 
25 (S4toS8) 

[0029] The control unit 4 designates to the decoder 3 
the address of the data area 1 2 to be buffered, the buffer 
pointer and the b uffer size (S4), and the decoder 3 com- 

30 pares the pointer of the buffer destination of the alter- 
nate list 13 and the buffer pointer while referring to the 
new alternate list 24 (S5). When they match with each 
other, buffering is not applied to the buffer pointer, and 
the buffer destination is updated to the next buffer point- 

& er(S6). 

[O030] When they do not match, the decoder 3 buffers 
the data acquired from the optical disk 2 in the buffer 
pointer and updates the buffer destination to the next 
buffer pointer (S7). The decoder 3 repeats the above 
40 processing for number of times corresponding to the 
buffer size (SB). 

1 .4 Buffering of the alternate area 13 in the pointer for 
the buffer destination of the alternate area 1 3 (S9 and 

45 S10) 

[0031] The decoder 3 refers to the new alternate list 

24, buffers the data of the address in the alternate area 
13 indicated in the new alternate list 24 to the pointer of 

so the buffer destination of the alternate area 13 indicated 
in the new alternate list 24 (S9). The above processing 
is repeated until the last member of the new alternate 
fist 24. (S10). 

55 1 .5 Transfer of buffered data to the host computer 1 
(811 J 

[0032] The control unit 4 transfers the buffered data 



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obtained by the processings 1. 1 to 1.4 to the host com- 
puter 1 . 

[0033] The above procedure provides data access 
which can eliminate unwanted caching. 
[0034] Next, the operalion of the optical disk device 
1 0 of the first embodiment according to the invention will 
be described using specific numerical values. 

2. 1 Acquisition of the alternate list (S1 and S2) 

[0035] The control unit 4 designates to the decoder 3 
a value N for the alternate list 1 1 of the optical disk 2, a 
value2forthe alternate list acquisition size, and a value 
X for the alternate list acquisition pointer (SI), The de- 
coder 3 stores the alternate list 11 in the area of the al- 
ternate iist temporary storage memory area 21 with the 
designated pointer at the head from the address desig- 
nated by the optical disk 2 (S2). 2. 2 Construction of a 
table formed of the addresses of the detective area and 
pointers of buffer destinations of the alternate area 13 
(S3) 

[0036] The control unit 4 constructs, from the aiter- 
natelis124, avalueWforthe buffer pointer, anda value 
6 for the buffer size, the new alternate list 24 having the 
address of the alternate area 13 and the pointer of the 
buffer which buffers its alternate area 13 as a set, at the 
position represented by the new alternate list pointer of 
the alternate list temporary storage memory area 21 . 

2. 3 Buffering only of normal area of the data area 12 
(S4 to SB) 

[0037] The controi unit 4 designates to the decoder 3 
a value M for the address of the data area 1 2 of the op- 
tical disk2to be buffered, a value W for the buffer point- 
er, and a value 6 lorthebuffer size (S4), and the decoder 
3 compares the pointer of the buffer destination of the 
alternate area 13 indicated In the new alternate list 24 
and the buffer pointer(S5). Since there can be found no 
matching, the decoder 3 buffers the data DA0 acquired 
from the optical disk 2 in the buffer pointer W and up- 
dates the buffer destination to the next buffer pointer 
W+1 (S7). Since the buffer size 6 is not reached yet, the 
processing is continued (S8). 

[0038] Since no matching is found forthebufferpoint- 
er W+1 either, the data DA1 shown for the address M+1 
of the data area 12 of the optical disk 2 is buffered at the 
buffer pointer W+1, and updates the buffer destination 
to the next buffer pointer W+2 (S7). Since the buffer size 
of 6 is not achieved yet, the processing is continued 
(S8). 

[0039] Since the buffer pointer of W+2 matches the 
pointer of the buffer destination of the alternate area 13 
shown by a new alternate list pointer Y of the new alter- 
nate list 24, the buffer pointer of W+2 is skipped (S6). 
Since thebuffer size of 6 is not reached yet, teleprocess- 
ing is continued (S8). 

[0040] Sinceno matchi ng is fou nd fo r the buffer point- 



er W+3 among the pointers of the buffer destination of 
the alternate area 13 shown in the new alternate list 24, 
a data DA3 shown at the address M+3 of the data area 
of the optical disk 2 is buffered in the buffer pointer W+3, 

5 and the buffer destination is updated to the next buffer 
pointer W+4 (S7). Since the buffer size 6 is not reached 
yet, the processing is continued (S8). 
[0041] Since the buffer pointer of W+4 matches the 
pointer of the buffer destination of the alternate area 13 

fo shown by a new alternate list pointer Y+1 of the new 
alternate list 24, the buffer pointer of W+4 is skipped 
(S6). Since the buffer size of 6 is not reached yet, the 
processing is continued (S8). 
[0042] Since no pointer is found among the pointers 

'5 of the buffer destination of the alternate area 1 3 shown 
in the new alternate list 24 that matches the bufferpoint- 
er W+5, data DA5 shown by address of M+5 of the data 
area 12 of the optical disk 2 is buffered at the buffer 
pointer W+6, and the buffer destination is updated to the 

™ next buffer pointer W+6 (S7). Since the buffer size con- 
dition of 8 is satisfied, the buffer processing for only the 
normal areas of the data area 1 2 is completed (S8). 
[0043] As a result of the above operation, the buffer 
pointers (W, W+1, W+3 and W+5) for which matching is 

25 found between the buffer pointers shown by the new al- 
ternate list 24 and the buffer pointers of the data tempo- 
rary storage memory area 21 which are buffered by the 
decoder 3, the normal data of the data area 1 2 are buff- 
ered, and the buffer pointers (W+2 and W+4) for which 

30 matching is not found are skipped. Accordingly, the pol- 
icy of "making reference to the new alternate list 24 of 
the alternate area 13 and its buffer destination to per- 
form buffering only for the normal area and not perform 
buffering for the fault area" has been observed. 

35 

2.4 Buffering of the alternate area 13 to designated 
buffer area (S9 and S 10) 

[0044] The decoder 3 refers to the new alternate list 
« 24, and buffers the data SAO of the address K of the 
alternate area 1 3 shown by the new alternate list pointer 

Y in the pointer W+2 of the buffer destination of the al- 
ternate area 1 3 shown by the new alternate list pointer 

Y (S9). Since the last member of the new alternate list 
« 24 is not reached yet, the new alternate list pointer is 

updated, and the processing by setting the new alter- 
nate list pointer to Y+1 is continued (S10). The data SA1 
of address K+1 of the aiternate area 13 shown for the 
new alternate list pointer Y+1 is buffered in the pointer 

so w+4 of the buffer destination of the alternate area 1 3 
shown by the new alternate list pointer Y+1 (S9). Since 
the last member of the new alternate list 24 is reached, 
the processing of buffering the alternate area 13 in the 
designated area is completed (S1 0). 

ss [0045] From what has been described in the above, 
the data (K and K+1) of the alternate area 13 shown by 
the new alternate list 24 are buffered in the pointers 
(W+2 and W+4) of the buffer destination of the alternate 



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area 13 shown by the new alternate list 24. Accordingly, 
the buffering policy of "making reference to the new al- 
ternate list 24 to buffer the alternate area 1 3 in+ the buff- 
er area shown by the new alternate list 24" has been 
executed. 

2.5 Transfer of buffering data to the host computer 1 
(811) 

[0046] The control unit 4 transfers the data (DAO, 
DA1 , SAO, DA3, SA1 and DA5) of the buffer pointers W 
to W+5 buffered in 2.1 to 2. 4 to the host computer 1 . 
[0047] From 2. 1 to 2 . 5, it can be seen that it is pos- 
sible to realize buffering from the optical disk 2 without 
the use of caching by the combination of the two buffer- 
ing policies of "making reference to the alternate area 
13 and the new alternate list 24 of its buffer destination 
to buffer only the normal area, and not to buffer the de- 
fective area" and of "making reference to the new alter- 
nate list 24 to buffer the alternate area 13 in the buffer 
area shown by the new alternate list 24." 
[0048] Referring to FIG. 1 and FIG. 3, a second em- 
bodiment of this invention will be described. FIG. 3 is a 
flow chart sh owin g the data buff er flow chart of th e sec- 
ond embodiment of the invention. 

3. 1 Acquisition of the alternate list (S1 and S2) 

[0049] The operation is the same as in 1 . 1 of the first 
embodiment, so it will be omitted. 

3. 2 Construction of a table of addresses of defective 
area and pointers of buffer destination of the alternate 
area 13 (S3) 

[0050] The operation is the same as in 1 . 2 of the first 
embodiment, so it will be omitted. 

3. 3 Buffering of the alternate area 13 in the pointers of 
buffering destination of the alternate area 13 (S9 and 
S10) 

[0051] The decoder 3 refers to the new alternate list 
24, and buffers address data of the alternate area 13 
shown in the new alternate list 24 to the pointers of buffer 
destination of the alternate area 13 shown in the new 
alternate list 24 (S9). The above processing is repeated 
to the last member of the new alternate list 24 (S1 0). 

3. 4 Buffering of only the normal area of the data area 
12(S4toS8) 

[0052] The control unit 4 designates to the decoder3 
the address of the data area 1 2to be buffered, the buffer 
pointer, and the buff ersiz© (S4), and the decoder 3 com- 
pares the pointer of the buffer destination of the alter- 
nate area 13 and the buffer pointer (S5). When they 
match, buffering is not performed to the buffer pointer 



and the buffer destination is updated to the next buffer 
pointer (S6). 

[0053] When they do not match, the decoder buffers 
the data acquired from the optical disk 2 in the buffer 
s pointer, and updates the buffer destination to the next 
buffer pointer (S7). The decoder repeats the above 
processing for number of times corresponding to the 
buffer size. (S8). 

10 3. 5 Transfer of the buffered data to the host computer 
1 (S11) 

[0054] The operation is the same as in 1 . 5 of the first 
embodiment, so it will be omitted. 
'5 [0055] From the processings 3.1 to 3.5, it is possible 
to realize buffering of data from the optical disk 2 without 
the use of caching similar to the first embodiment. 
[0056] As described in the above, according to the 
present invention, there is no need for caching an alter- 
20 nate area which is substituted for the fault area, and it 
is possible to realize a temporary storage memory area 
with smaller capacity for buffering information needed 
until the transfer of data to the host computer. Moreover, 
it is possible to reduce the processing time for buffering. 
25 [0057] Although the Invention has been described 
with reference to specific embodiments, 1he description 
is not meant to be co nstrued i n a II miting sense . Various 
modifications of the disclosed embodiments will be- 
come apparent to persons skilled in the art upon refer- 
so ence to the description of the invention. It is therefore 
contemplated that the appended claims will cover any 
modifications or embodiments as fall within the true 
scope of the invention. 



Claims 

1. An optical disk device comprising: 

to means for reading data of an optical disk, the 

disk being provided in advance with an alter- 
nate area that serves as its substitute when a 
defect exists in a data area and being recorded 
in advance with list information consisting of a 

& plurality of sets each of the set being formed of 

a position on the disk of the data area and an 
address of the alternate area, and buffering a 
data area that is defective after correcting it, 
and 

50 means for storing a new alternate list on which 

is recorded the correspondence relationship 
between said alternate area and its buffer des- 
tination, 

wherein said means for buffering after correc- 
ts tion is equipped with 

a normal databuffermeans which refers to said 
new alternate list and buffers data in a normal 
area without buffering data in a defective data 



s 



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EP 1 274 081 A2 



area, 

an alternate data buffer means which refers to 
said new alternate list and buffers data in said 
alternate area in a buffer area shown in the new 
alternate list, and s 
a final data-buffer means which buffers an al- 
ternate data in a data area which is defective in 
the buffered data obtained by means of said 
normal data buffer means, by combining the 
b uffered data obtai ned by means of said normal f o 
data buffer means and the buffered data ob- 
tained by means of said alternate data buffer 
means. 

The optical disk device as claimed in claim 1, « 
wherein said optical disk is a rewritable optical disk 
equipped respectively with an alternate list and an 
alternate area in the unit of tracks. 



25 



45 



EP 1 274 081 A2 



Rewritable OPTICAL DISK 



ALTERNATE LIST 



ADDRESS OF ALTERNATE LIST ON DISK 


— ¥ — 


N+1 


DATA{ALTERNATE SOURCE/ALTERNATE 
DESTINATION ADDRESS) 


M+2 | K 


M+4 


K+1 



ADDRESS OF DATA AREA 



DATA 



DAP 



M+1 
DAI 



y DATAAR£A_ 1 £ 



M+3 M+4 M+5 

da3 Vmm DA5 



ADDRESS OF DATA AREA 


K 


K+1 


I ALTERNATE DATA 


SAO 


SA1 



,13 



DECODER 



TEMPORARY STORAGE MEMORY AREA 



CONTROL _4 

unit r 



ALTERNATE 
LIST POINTER 


ADDRESS OF 
DEFECTIVE AREA 
ADDRESS OF 
ALTERNATE AREA 


X 


M+2 


K 


X+1 


M+4 


K+1 


23* ALTERNATE UST 


NEW 

ALTERNATE 
LIST POINTER 


ADDRESS OF 
ALTERNATE AREA 


ALTERNATE AREA 
ACQUISITION 
DESTINATION POINTER 


Y 


K | 


W+2 


Y+1 


K+1 


W+4 



NEW ALTERNATE LIST 



ALTERNATE LIST TEMPORARY STORAGE 
MEMORY AREA 



BUFFER 
POINTER 


NORMAL 
DATA,, 




BUFFER 
POINTER 


ALTERNATE 

DATA 


W 


□AO 




W 




W+1 


DA1 




W+1 




W+2 


mm. 




W+2 


■mm* 


W+3 


DA3 




W+3 




W+4 


W////A 




W+4 




W+5 


DA5 




W+5 




\ NORM 


M-DATA ALTERN 


ATE DATA ) 



BUFFER 
POINTER 


DATA 


W 


DAO 


W+1 


DA1 


W+2 


SAO 


W+3 


DA3 


W+4 


SA1 


W+5 


DAB 



BUFFERING 
DATA 



DATA TEMPORARY 
STORAGE 
MEMORY AREA 



22 



hqstcomputerT - 1 



FIG.1 



6 



BNSDOCID: <EP 127-)0S1A2_I_> 



EP 1 274 081 A2 



DATA BUFFERING IN THIS INVENTIOI [ . ) 



DESIGNATION OF ADDRESS OF ALTERNATE LIST, 
ALTERNATE LI ST ACQUISITION SIZE, AND POINTER 
OF ALTERNATE LIST ACQUISITION DESTINATION 



-S1 



7 iNATE LIST ACQUISITION \ < 



CONSTRUCTION OF TABLE OF ALTERNATE AREA 
ADDRESS AND POINTER OF BUFFER DESTINATION 
(CONSTRUCTION OF NEW ALTERNATE LIST) 



-S3 



DESIGNATION OF DATA AREA ADDRESS, h-S4 
BUFFER POINTER, AND BUFFER SIZE 




S7 



ACQUISITION OF DATA 
AREA IN BUFFER 



COMPLETION^ 
* YES 



ACQUISITION OF ALTERNATE AREA IN BUFFER~T -S9 
,S10 

Completions 
Tyes 



no 




TRANSFER OF BUFFER DATA~T ~S1 1 

™ 



( END ) 

FIG.2 



9 



BNSDOCID: <EP 1274081 A2_L> 



EP 1 274 081 A2 



( DATA BUFFERING IN THIS INVENTION _ 



DESIGNATION OF ADDRESS OF ALTERNATE LIST, 
ALTERNATE LIST ACQUISITION SIZE, AND POINTER 
OF ALTERNATE LIST ACQUISITION DESTINATION 



-S1 



I ALTERNATE LIST ACQUISITION \ ^S2 



CONSTRUCTION OF TABLE OF ALTERNATE AREA 
ADDRESS AND POINTER OF BUFFER DESTINATION 
(CONSTRUCTION OF NEW ALTERNATE LIST) 



-S3 



ACQUISITION OF ALTERNATE AREA IN BUFFER K S9 
S10 

^COMPLETIONS 

_]Y_i_T_ J 



NO 




DESIGNATION OF DATA AREA ADDRESS, h-S4 
BUFFER POINTER, AND BUFFER SIZE I 




,S7 



ivcc ACQUISITION OF DATA 
SKIPTHEBUFFER I . j/™"*™ 




completions 
Tyes 



TRANSFER OF BUFFER DATA "K S1 1 



C END ) 

FIG.3 



10 



EP 1 274 081 A2 



OPTICAL DISK DEVICE 



10 



Rewritable OPTICAL DISK 




CONTROL 
UNIT 



TEMPORARY STORAGE 
MEMORY AREA 



/ / 

HOST COMPUTER 
V 

FIG.4 



11 



EP 1 274 081 A2 



Rewritable OPTICAL DISK 



ADDRESS OF ALTERNATE LIST ON DISK 


N 


N+1 1 


DATA(ALTERNATE SOURCE/ALTERNATE 
DESTINATION ADDRESS) 


M+2 | K 


M+4 | K+1 



ADDRESS OF DATA AREA M M+1 M+2 M+3 M+4 M+5 
DATA DAQ I DAI foDhZ'd DA3 Wtfm DAT 



ALTERNATE AREA 



ADDRESS OF DATA AREA 


K 


K+1 


ALTERNATE DATA 


SAO 


SA1 



TEMPORARY STORAGE MEMORY AREA 



M CONTROL _4 
UNIT 



ALTERNATE 
LIST POINTER 


ADDRESS OF 
DEFECTIVE AREA 
ADDRESS OF 
ALTERNATE AREA 


X 


M+2 


K 


X+1 


M+4 


K+1 



44 



ALTERNATE LIST 



TABLE 
POINTER 


ADDRESS OF 
DEFECTIVE AREA 


CACHE POINTER 


Y 


M+2 


Z 


Y+1 


M+4 


Z+1 



45 i^Aunt lAHLt 

ALTERNATE LIST TEMPORARY 
.-STORAGE MEJTOR^Aj^EA | 

41 



CACHE 


ALTERNATE 


Z 


DAD 


Z+1 


DA1 



BUFFER 
POINTER 


DATA 


W 


DAO 


W+1 


DA1 


W+2 


SAO 


W+3 


DA3 


W+4 


SA1 


W+5 


DA5 



> BUFFERING 



47 



DATA 



DATA TEMPORARY 
STORAGE 
MEMORY AREA 

-r- 



42 



[ HOST COMPUTER | 



FIG.5 



12 



BfJSDOCID: iEP 1374081 A2 1 > 



EP 1 274 081 A2 



C D/-.P . . "FERING IN PRIORAOTJ 



DESIGNATION OF ADDRESS OF ALTERNATE LIST, 
ALTERNATE LIST ACQUISITION SIZE, AND POINTER 
OF ALTERNATE LIST ACQUISITION DESTINATION 



S1 



t , ( DATA ACCES S PROCESSING ) 

ALTERNATE LIST ACQUISITION h -S2 T 



DESIGNATION OF DATA AREA ADDRESS, - S23 
BUFFER POINTER. AND BUFFER SIZE 



BUFFERING OF DATA AREA j-S24 



CHECK ALTERNATE LIST, AND DECIDE WHETHER 
DEFECTIVE AREA IS INCLUDED IN TARGET AREA | 




^DEFECTIVE DATA? 

TVES J332 | TRANSFER OF BUFFERED DATA! 



FIG.6 



13