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<» UK Patent Application (n9 ,GB ,,,,2 356735 n 3 ,A 



(43) Date of A Publication 30.05.2001 



(21) 
(22) 


Application No 0025335.1 
Date of Filing 03.08.1999 
Date Lodged 16.10.2O0O 


(51) 
(52) 


INT CL 7 

G11B 20/18 

UK CL (Edition S ) 
G5R RB265 RB33 




(30) 


Priority Data 

(31) 10222003 (32) 05.08.1998 (33) JP 


(56) 


Documents Cited 
US 5237553 A 




(62) 


Divided from Application No 9918310.5 under Section 
15(4) of the Patents Act 1977 


(58) 


Field of Search 
UK CL (Edition S ) GSR RB27 RB33 
INT CL 7 G11B 20/12 20/18 
EPODOC; JAPIO; WW 




(71) 


Applicant(s) 






(72) 


Mitsubishi Denki Kabushiki Kaisha 
(incorporated in Japan) 
2-3 Marunouchi 2-chome, Chiyoda-ku, 
Tokyo 100-8310, Japan 

Inventor(s) 


(74) 


Agent and/or Address for Service 
R.G.C.Jenkins 8e Co 

26 Caxton Street, LONDON, SW1H ORJ, 
United Kingdom 





Kazuhiko Nakane 
Hiroyuki Ohata 



(54) Abstract Title 

Managing defects in an optical disk 

(57) When optical disk defects are managed by using non-defective areas in place of defective areas, different 
criteria are used for detecting the defects, depending on the type of data recorded on the disk. For example, to 
avoid interruptions of real-time recording, less strict criteria are used when audio or video data is recorded 
than when computer data is recorded. The criteria themselves may also be recorded on the disk. 

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2356735 



METHOD OF MANAGING DEFECTS IN AN OPTICAL DISK, 
AN OPTICAL DISK DEVICE AND AN OPTICAL DlSK 

BACKGROUND OF THE INVENTION 

The present invention relates to a method of managing 
defects in a disk recording medium, an optical disk device 
recording data on the optical disk using such a defect 
management method, and an optical disk capable of storing 
information concerning a defect criteria used for replacing 
a defective area of disk with a non-defective area.^ 

A very high degree of reliability less than 10 at 
worst is required of a disk used for recording computer 
data. Defect-managing systems have been used hitherto to 
accommodate the reality that defects in recording sectors 
which lead to an error are unavoidable, even very rare, in 
the current disk-manufacturing technique. 

Disk mediums are subjected to the defect management for 
assuring data reliability even when dirt, scratches or 
degradation due to repetition of rewriting operation is 
caused. Primary defects occurring at the time of 
manufacture of the disks are found through a certifying 
process carried out at the time of initializing disks, and 
secondary defects occurring after being put to use are found 
through verification carried out at the time of writing, or 
the like. Sectors found to have a defect are replaced, 
using sectors located in a spare area formed on part of a 
disk other than a user area. In the defect management, a 
pair of a user area and a spare area is called a group. 

In an example of arrangement of user areas and spare 
areas on a disk, the data area consists of a single group. 
However, there are many optical disks in which a data area 
is divided into a plurality of groups. When a defective 
group is found in a group, it is first attempted to replace 
the defective sectors using sectors in a spare area of the 



1 



same group . In many cases, an optical disk is configured 
such that a recording capacity of a spare area is several % 
of that of a user area. The 90mm magneto-optic disk 
standard defined by ECMA-154 or ECMA-201, and the DVD-RAM 
standard defined by ECMA-272 are examples of such 
configuration . 

Incidentally ECMA is an abbreviation of European 
Computer Manufacturers Association , DVD is an abbreviation 
of digital video disk, and RAM is an abbreviation of random- 
access memory. 

The presence or absence of a defect in a sector can be 
determined by an error in an ID signal representing a 
physical address of the sector, an error in a recorded data 
signal, or a servo error signal. 

When a plurality of ID * s are recorded in the header 
area for each sector, if not less than a predetermined 
number of ID'S for each sector contain an error, the sector 
in question is found have a header defect. In DVD-RAM 
standard for example, each sector is provided with four 
ID f s, and an error can be detected for each ID. Each sector 
is not found to have a header defect it has not more than 
two ID errors: a sector having three or more ID errors is 
found to have a header defect, since its reliability is low. 

Further, the presence or absence of an error in a 
recorded data signal is detected by the use of an error 
correcting code added thereto. When more than a 
predetermined number of errors are included per unit of 
recording, the data signal is found to have a data defect. 
The "unit of recording" may be a sector or a block 
constituted of a plurality of sectors depending on the span 
of an error correcting code (ECC) . 

In the DVD-RAM standard, data is recorded in sectors on 
a disk, and is subjected to error-correcting coding in units 
of 16 sectors, called an ECC block. Data of 32 KB 



2 



constituting one ECC block is arranged in the form of matrix 
of 172 x 192 bytes (or 172 columns x 192 rows), and Reed- 
Solomon codes (inner code PI, outer code PO) of 10 bytes and 
16 bytes are added in column direction and row direction, 
respectively, to constitute a product code. 

The inner code PI is disposed so as to be complete 
within a sector. By means of the inner code PI, the number 
of error bytes in each row of the reproduced data can be 
determined. In accordance with the detected number of 
errors, reliability of each row is evaluated, and whether 
each sector or each block has a data defect can be 
determined based on the number. For instance, a sector 
including four or more rows having four or more error bytes 
is found to be have a data defect, or a block including six 
or more such rows are found to have a data defect. 

With regard to detection of defects based on a servo 
error signal, when the magnitude of the servo error signal 
such as a tracking error signal exceeds a predetermined 
value that makes it difficult to ensure the servo control 
stability required of data recording, a sector in question 
is found to have a servo defect. 

When a sector is found to have a header defect, a data 
defect or a servo defect, it is found to be defective. 

Generally, in the defect management, two different 
methods are used for performing replacement of a sector. 
One is a slip replacement, and the other is a linear 
replacement . 

The slip replacement is applied to primary defects. If 
a defective sector is found at the time of certifying a 
disk, the next sector is used in place of the defective 
sector. In a disk drive device, for accessing a sector 
containing data, a logical address is converted into a 
physical address representing the position of the sector, 
and a sector having ID's representing the physical address 



3 



is accessed. When the slip replacement has been performed, 
the physical address numbers corresponding- to the logical 
addresses are shifted, or "slip" by one. 

The slip replacement is carried out within each group. 
For instance, if there occur two slip replacements of m 
sectors and n sectors in a user area, the end of the user 
area of the group is shifted into the head of the spare area 
by (m+n) sectors. If such slip replacements are made, the 
linking- relation between the physical addresses and logical 
addresses is shifted by the number of replaced sectors for 
all the sectors succeeding the replaced sectors. Primary 
defects subjected to the slip replacement are registered in 
a PDL (Primary Defect List). The list contains the physical 
addresses of defective sectors in each entry. 

Linking the physical addresses with the logical 
addresses can be made only when a disk is initialized, and 
therefore, the slip replacement is applied to primary 
defects only. 

The linear replacement is applied to secondary defects. 
When a defective sector is found, replacement is effected 
using spare sectors in a spare area. When an ECC block 
(formed of 16 sectors) is found to contain a defective 
sector, the entire ECC block is replaced with 16 sectors in 
a spare area. There may be a case where a block in a spare 
area having- replaced another block is subsequently replaced 
with another block. A substitutive sectors are given the 
same logical addresses as the original sectors. 

The linear replacement is effected within the same 
group first. For instance, when two linear replacements of 
m blocks and n blocks respectively occur in a user area, m 
blocks and n blocks at the beginning of the unused part of 
the spare area are used. It may be so designed that when 
the spare area of the same group has been used up the spare 
area in another group is used. Secondary defects subjected 



4 



to linear replacement are registered in an SDL (Secondary 
Defect List). The list contains physical addresses of 
defective sectors and substitutive sectors in each entry. 

When such a linear replacement has been made, every 
time an access is made using a logical address which 
designated a substitutive sector, an access to the 
substitutive sector and subsequent return have to be made. 
Therefore, the average data transfer rate is substantially 
lowered when the secondary defects exist. 

A set of the defect lists PDL and SDL is stored in a 
defect management area within a control information area in 
each of outer and inner periphery parts. They are disposed 
at a plurality of locations, and they are recorded together 
with information on the structure of a disk. 

Generally, in recording devices, criteria for detecting 
primary and secondary defects are set in the following way. 

A disk is at its best condition when primary defects 
are detected and registered. The number of defects on the 
disk increases with time or usage due to scratches and dirt, 
and resultant degradation. Therefore, the primary defects 
are detected and replacement is effected by using a criteria 
which is more strict than that for detecting the secondary 
defects, so that some additional scratches or dirt will not 
results in the finding of a defect according to the criteria 
for detecting the secondary defects. 

Although the secondary defects are detected with a 
criteria which is less strict than that for the primary 
defects, a margin of safety is left between the criteria for 
detecting the secondary defects and the error-correcting 
capability, so as to ensure error correction during 
reproduction. In this way, different criteria are used for 
the primary defect detection and the secondary defect 
detection . 

Conventionally, optical disks are used mainly for 



5 



computer dat^ recording, and therefore, the primary concern 
was to improve the data reliability, and defect management 
mainly consisting of replacement using spare sectors has 
been developed to deal with the defects in the recording 
sectors causing the errors. 

In recent years, with increasing capacity of optical 
disks, their uses are expanding to the video recording 
field, such as in DVD. 

Data files for recording computer data (PC files) are 
expected to be completely error-free, and high reliability 
is required of recording. In contrast, data files for 
recording audio or vide^ data (AV files) require recording 
data inputted continuously in real time. In some cases, 
errors are permissible as long as the disturbance of 
reproduced images or sounds is not noticed, so that data 
reliability Is not required to be as high as in computer 
data recording. Instead, non- interrupt ion of recording is 
important . 

That is to say, with regard to storage devices for 
computer data recording, primary importance is the 
reliability rather than recording time, while, for storage 
devices for video recording, primary importance is 
continuous recording performance. Consequently, in case of 
using the same type of disk for recording both audio or 
video data and computer data, it is required to ensure 
reliability and recording speed which meet the requirements 
of the respective recordings. Likewise, defect management 
is required to be adaptable to both types of recording. 

Conventional defect management for optical disks has 
the following drawbacks. 

For carrying out replacement to deal with secondary 
defects of a disk at the time of recording, data is 
reproduced from the recorded part for verification, and if 
errors of more than a prescribed criteria, or a defective 



6 



part from which reproduction is impossible is found, the 
"\data recorded in that part is re-recorded in substitutive 
sectors in a spare area, and data is again reproduced from 
the substitutive sectors for verification. Thus, when a 
secondary defect is detected, and replacement is effected, 
the time needed is four times more of the time needed for 
recording- data once. In case of recording audio or video 
data in real time, it is likely that recording is 
interrupted if a defect is detected. 

One solution to this problem is not to detect secondary 
defects during the recording audio or video data. In this 
case, the reproduced image or the like may have disturbances 
at parts having the secondary defects, but they are 
considered less objectionable than interruption of 
recording. The underlying assumption is that once primary 
defects have been removed at the time of initialization of 
the disk, any secondary defects that might occur will be 
minor. If the scale of the secondary defects are beyond the 
prediction, the disturbance of the reproduced picture may be 
intolerable, and thus this solution fails. 

Where the optical disks are used for recording audio or 
video data, it is considered unnecessary to detect defects 
with criteria which is as strict as that used in recording 
computer data. This is because, if the excessively strict 
criteria is used, sectors which are permissible for audio or 
video data are also found defective, and video recording is 
interrupted when the time-consuming replacement is effected. 
Because the conventional defect management method does not 
take into consideration the intended use of the optical 
disk, and the criteria used is of the same level regardless 
of the intended use of the optical disk, and there was no 
conception of using the optimum defect detecting method. 

SUMMARY OF THE INVENTION 



7 



The present Invention has been made overcome the above- 
outlined problem, and its object is to adapt defect 
management to the type of data recorded on an optical disk, 
or the intended use of the disk. 

Another object is to improve the interchangeability of 
the optical disk. 

A further object is to improve the utility of optical 
disks for recording audio or video data. 

According- to a first aspect of the invention, there is 
provided a method of managing* defects on an optical disk 
used for recording data, comprising the steps of 

determining a criteria for detecting said defects 
according to the type of data for which defects are to be 
detected; and 

detecting said defects using said criteria when data is 
recorded on or reproduced from said disk. 

With the above arrangement, it is possible to use the 
criteria suitable for the particular type of data for which 
said defects are to be detected. 

Said step of detecting said defects may be performed 
with regard to data recorded on the disk. 

In this case the defects may be detected when the data 
is recorded on the disk, or when the data is reproduced for 
verification of the data having been recorded. When the 
defects are detected when the data is recorded, 
determination of presence or absence of servo defects and 
header defects can be made, but determination of presence or 
absence of data defects cannot be made. When the defects 
are detected during reproduction for verification, presence 
of absence of data defects as well as servo defects and 
header defects can be determined. 

Said step of detecting said defects may alternatively 
be performed when the data is reproduced. In such a case, 
if defects are detected, the reproduction of the data is re- 



8 



tried. Decision on whether the reproduction is to be re- 
tried is made using different criteria depending on the type 
of data being reproduced. 

The method may further comprise the step of using non- 
defective areas of the optical disk in place of defective 
areas of the optical disk. 

With the above arrangement, the result of the defect 
detection can be used in making a decision as to whether the 
areas found to be defective should be replaced with non- 
defective areas. 

Said step of determining a criteria may include: 
providing a plurality of criteria; and 
selecting one of said plurality of criteria according 
to the type of data for which defects are to be detected. 

With the above arrangement, the defect criteria can be 
determined simply by providing a signal which selects one of 
the plurality of criteria provided in advance, rather than 
specifying the values forming the criteria. 

Said plurality of criteria may include at least a first 
criteria, and a second criteria, said second criteria being 
less strict than said first criteria, and said step of 
selecting may comprise selecting said first criteria when 
the data for which defects are to be detected is one for 
which time restriction with regard to data recording or 
reproduction is less strict, and selecting said second 
criteria when the data for which defects are to be detected 
is one for which time restriction with regard to data 
recording or reproduction is more strict. 

An example of the data for which time restriction with 
regard to data recording or reproduction is less strict is 
computer data. An example of the data for which time 
restriction with regard to data recording or reproduction is 
more strict is audio or video data. 

By using a less strict criteria for the audio or video 



9 



data, interruption of the audio or video data recording- is 
avoided unless the defect is of such a degree that the 
resultant disturbance in the sound or picture is 
intorerable . 

The method may further comprise the step of sending 
control information for specifying: said criteria, from means 
for processing data to be recorded, to means for recording 
said data. 

The above-mentioned means for processing data to be 
recorded is for example a host device. The above mentioned 
means for recording the data is for example a disk device. 

With the above configuration, the host device can set 
criteria which is finely optimized for the type of the data 
to be recorded on the disk. 

The data may be recorded in units of recording, and 
said step of sending control information may send the 
control information for each each unit of recording. 

With the above configuration, it is possible to 
dynamically set criteria which is finely optimized for each 
unit of recording (e.g., sector or ECC block), depending on 
the type of the data to be recorded in each unit of 
recording. That is, even when different types of data, 
e.g., audio or video data, and computer data, are both 
recorded on the same disk, since the host device sends the 
criteria control information in association with the data to 
be recorded, and the defect management can be effected using 
the optimum criteria for the respective data. 

Said control information specifying the criteria may 
select one of a plurality of criteria. 

With the above configuration, the amount of control 
information is small, since it only needs to specify one of 
the plurality of predetermined criteria, rather than 
specifying values forming the criteria itself. 

Data may be recorded in units of recording, and said 



10 



method may further comprise the step of recording control 
information representing the criteria for each unit of 
recording, on the optical disk, in association with said 
each unit of recording. 

With the above configuration, the criteria to be used 
for defect detection for each unit of recording (sector or 
ECC block) is known by reading the control information, and 
can be used for performing maintenance of the data recorded 
on the disk. 

According to a second aspect of the invention, there is 
provided a disk device for accessing data on an optical 
disk, comprising: 

means for determining a criteria for detecting said 
defects according to the type of data for which defects are 
to be recorded; and 

means for detecting said defects using said criteria 
when data is recorded on or reproduced from said disk. 

With the above arrangement, it is possible to use the 
criteria suitable for the particular type of data for which 
defects are to be recorded. 

Said detecting means may detect said defects with 
regard to data recorded on the disk. 

In this case the defects may be detected when the data 
is recorded on the disk, or when the data is reproduced for 
verification of the data having been recorded. When the 
defects are detected as the data is recorded, servo defects 
and header defects can be detected, but data defects cannot 
be detected. When the defects are detected during 
reproduction for verification, data defects as well as servo 
defects and header defects can be detected. 

The detecting means may alternatively detect defects 
when the data is reproduced. In such a case, if defects are 
detected, the reproduction of the data is re-tried. 
Decision on whether the reproduction is to be re-tried is 



11 



made using: different criteria depending on the type of data 
being reproduced. 

Said device may comprise means for managing- defects on 
the optical disk by using non-defective areas of the optical 
disk in place of defective areas. 

With the above arrangement, the result of the defect 
detection can be used in making a decision as to whether the 
areas found to be defective should be replaced with non- 
defective areas. 

Said determining means may comprise: 
means for storing a plurality of criteria; and 
means for selecting one of said plurality of criteria 
according to the type of data for which defects are to be 
detected . 

With the above arrangement, the defect criteria can be 
determined simply by applying a signal for selecting one of 
the plurality of criteria provided in advance, rather than 
specifying the values forming the criteria. 

Said plurality of criteria may include at least a first 
criteria, and a second criteria, said second criteria being 
less strict than said first criteria, and said selecting 
means may select said first criteria when the data for which 
defects are to be detected is one for which time restriction 
with regard to data recording or reproduction is less 
strict, and selects said second criteria when the data for 
which defects are to be recorded is one for which time 
restriction with regard to data recording or reproduction is 
more strict. 

An example of the data for which time restriction with 
regard to data recording or reproduction is less strict is 
computer data. An example of the data for which time 
restriction with regard to data recording or reproduction is 
more strict is audio or video data. 

By using a less strict criteria for the audio or video 



12 



data, interruption of the audio or video data recording is 
avoided unless the defect is of such a degree that the 
resultant sound or picture is intolerable. 

Said determining means may determine the criteria 
according a control signal supplied from outside of the 
device . 

The control signal may be supplied from a host device 
connected to the disk device. 

With the above configuration, the host device can set 
criteria which is finely optimized for the type or contents 
of the data for which defects are to be detected. 

The device may further comprise means for recording 
data, in units of recording, on the disk, 

wherein 

said determining means may determine the criteria for 
each of said units of recording, and 

said recording means may also record criteria control 
information controlling the criteria for each unit of 
recording, in association with said each unit of recording. 

With the above configuration, the criteria to be used 
for defect detection for the data of each unit of recording 
(e.g., sector or ECC block) is known by reading the control 
information, and can be used for performing maintenance of 
the data recorded on the disk. 

According to a third aspect of the invention, there is 
provided an optical disk for recording data, comprising an 
area storing criteria control information specifying 
criteria to be used for detecting defects for data recorded 
on or reproduced from the disk. 

With the above configuration, the criteria to be used 
for detecting defects when the disk is accessed is known by 
reading the criteria control information recorded on the 
disk. Accordingly, the maintenance of the data on the disk 
is facilitated, and the interchangeability of the disk is 



13 



improved since the criteria control information can be read 
by any disk device. 

Said data may be recorded in units of recording, and 
said criteria control information indicating the criteria to 
be used for detecting detect with regard to said each unit 
of recording may be recorded in association with said each 
unit of recording. 

With the above configuration, the criteria to be used 
for each unit of recording, e.g., sector or ECC block, is 
known by reading the criteria control information, and can 
be used for performing maintenance of the data recorded on 
the disk. 

Said information may select said criteria from a 
plurality of predetermined criteria. 

With this configuration, the amount of control 
information is small, since it only needs to specify one of 
the plurality of predetermined criteria, rather than 
specifying values forming the criteria itself. 

BRIEF DESCRIPTION OF THE DRAWINGS 

In the accompanying drawings : - 

Fig. 1 is a block diagram of an optical disk device of 
an embodiment of the present invention; 

Fig. 2 is a block diagram of a defect determining means 
used in the optical disk device of Fig. 1; 

Fig. 3A is a schematic diagram showing examples of 
deformation of a groove forming a track; 

Fig. 3B is a time chart showing a tracking signal 
obtained when the light spot follows the track shown in Fig. 
3A; 

Fig. 4A is a diagram showing the configuration of a 
sector on a DVD-RAM; 

Fig. 4B is a schematic diagram showing the signal 
obtained when the light spot follows the sector shown in 



14 



Fig:. 4A; 

Fig. 5 is a diagram showing an example of errors in an 
error correcting block; 

Fig. 6 is a table summarizing two sets of defect 

criteria; 

Fig. 7 is a table summarizing three sets of defect 
criteria; 

Fig. 8 is a block diagram of a defect determining means 
of another embodiment; 

Fig. 9 is a diagram showing an example of procedure 
followed for setting defect criteria; 

Fig. 10 is a diagram showing another example of 
procedure followed for setting defect criteria; 

Fig. 11 is a diagram showing the configuration of an 
example of defect criteria control information; and 

Fig. 12 is a view showing arrangement of information 
for controlling defect criteria on an optical disk. 

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 

Embodiments of the invention will now be described with 
reference to the attached drawings, in which like parts are 
indicated by like reference characters. 

Fig. 1 is a block diagram of an optical disk device 
used to implement the defect management method according to 
the invention. A disk rotating means 4 controls rotation of 
an optical disk 2 for recording and reproducing data. An 
optical head servo means 22 performs position control over 
an optical head 6 such that a light spot formed by a light 
beam focused by the optical head 6 follows the track on the 
disk 2. 

The light reflected from the optical disk 2 
representing the data recorded on the disk 2 is converted in 
the optical head 6 into an electrical signal, which is 
supplied to an address reproducing means 8 and a signal 



15 



reproducing* means 10. Based on an ID signal in the header, 
the address reproducing- means 8 reproduces the address of a 
sector currently accessed. The detected address is sent to 
a drive control means 14. The signal reproducing" means 10 
reproduces signals from the signals supplied from the 
optical head 6 in accordance with the recording- format, A 
data reproducing means 16 corrects errors in the reproduced 
signals to produce information, and outputs information to a 
host device (not shown) as reproduced data of the desired 
logical block. 

At that moment, the data reproducing means 16 can 
recognize a sector in which the required data is recorded on 
the basis of control signals received from the drive control 
means 14. Concurrently, the drive control means 14 sends a 
command to control the rotational speed of the disk 2, to 
the disk rotating means 4. Further, the drive control means 
14 determines the position on the disk, of the sector 
containing the information to be reproduced, and sends 
commands to the optical head access means 20 for moving the 
optical head 6 to the position of the sector. The drive 
control means 14 also sends commands to control the 
operation of the servo system. The optical head access 
means 20 and the optical head servo means 22 control the 
position of the optical head 6 in accordance with the 
received commands . 

A defect management control information detecting means 
18 reads control information necessary for performing defect 
management, from the reproduced data, and obtains 
information concerning defect management such as defect 
management method applied to the disk, arrangement of spare 
areas and user areas, status of use of substitutive sectors, 
and defect criteria. The information thus obtained is sent 
to the drive control means 14 and used for controlling 
devices engaged in defect management at the time of 



16 



recording or reproducing data. 

Incidentally, all the sectors on the disk are numbered 
with consecutive addresses from the inner or outer periphery 
of the disk. However, the addresses of user data recording 
sectors are not consecutive. This is because the physical 
addresses are assigned not only to the user data recording 
sectors, but also to sectors in spare areas provided for 
defect replacement and sectors in guard areas at zone 
boundaries in the case of a zone format disk. 

At the time of performing access from the host device 
through an interface, logical block numbers of a file system 
are used. Therefore, the disk device needs to perform 
conversion between a logical block number and a sector 
address. The conversion is carried out by the drive 
control means 14 in accordance with received information on 
defect management . 

In writing operation, data sent from the host device is 
first inputted to a data recording means 24. The data 
recording means 24 performs error correction coding on the 
data in accordance with a format, and outputs the data as 
signals to be recorded, with timings controlled in 
accordance with the sector addresses on the disk, having 
been detected by the control signals supplied from the drive 
control means 14. 

A signal recording means 26 modulates the received 
signals in accordance with a recording format and sends them 
to the optical head 6. 

The optical head 6 writes the signals into the optical 
disk 2 by driving a laser. 

At this moment, the optical head 6 is controlled such 
that a light spot traces the sector the data is to be 
recorded, by means of the optical head access means 20 and 
the optical head servo means 22. 

The drive control means 14 stores defect management 



17 



control information detected by the defect management 
control information detecting* means 18 at the time of disk 
loading. The logical block number of the block to be 
accessed is given by an interface control signal supplied 
from the host device, not shown. To be more specific, the 
host device sends a recording command specifying the logical 
block number of the block where the data is to be written, 
and the like, to the disk device, together with the data to 
be recorded, or sends a reproducing command specifying the 
logical block number of the block from which the data is to 
be read and the like, to the disk device. 

The drive control means 14 converts the logical block 
number of the block to be accessed, to physical addresses, 
using defect management information, and sends a command 
specifying the physical addresses of the sectors to be 
accessed, to the optical head access means 20 and data 
recording means 24 or data reproducing means 16. The 
physical addresses of the sectors currently accessed are 
reproduced by the address reproducing means 8, and inputted 
to the drive control means 14. Drive control operations 
such as control over the optical head access means 20 and 
data recording means 24 or data reproducing means 16 are 
performed on the basis of the detected current address and 
the target address. 

A defect determining means 12 makes judgment as to 
whether a sector is defective and is to be replaced. The 
defect determining means 12 receives information necessary 
for defect determination on each sector from the optical 
head servo means 22, address reproducing means 8, and data 
reproducing means 16, and determines presence or absence of 
a defect in accordance with a defect criteria set by the 
drive control means 14, and reports the results of the 
determination to the drive control means 14. When the 
sector having been accessed is determined as a defective 



18 



sector, the drive control means 14 performs the necessary 
processes. During recording, the drive control means 14 
interrupts the recording operation and causes the data of 
the block to be re-recorded in substitutive sectors. 
During verifying reproduction, the drive control means 14 
causes the data of the block having been recorded, to be re- 
recorded in substitutive sectors. During reproduction, the 
drive control means 14- causes the reproduction to be re- 
tried. These operations are pre-programmed into the drive 

control means 14. 

Fig. 2 shows the configuration of the defect 
determining means 12. It receives servo error signals such 
as a tracking error signal and a focus error signal from the 
optical head servo means 22. It also receives a header 
error signal representing the number of errors in ID's 
reproduced for each sector, from the address reproducing 
means 8. It also receives a data error signal representing 
the number of errors in the reproduced data from the data 

reproducing means 16. 

In this embodiment, the defect determining means 12 
includes two defect criteria storing means 34 and 36 for 
storing different defect criteria A and B , respectively. 
The two defect criteria A and B are inputted to a defect 
criteria selecting means 38, which selects and outputs 
either one of the two criteria A and B in accordance with a 
defect criteria setting signal CS . There are three outputs, 
Rs, Rd, and Rh. A reference signal Rs for detecting a servo 
defect is inputted to a servo defect detecting means 28, a 
reference signal Rh for detecting a header defect is 
inputted to a header defect detecting means 32, and a 
reference signal Rd for detecting a data defect is inputted 
to a data defect detecting means 30. They are compared with 
a servo error signal Es , a header error signal Eh, and a 
data error signal Ed in the respective defect detecting 



19 



means 28, 32 and 30, to detect presence or absence of a 
servo defect, a header defect, and a data defect. A defect 
detecting means 40 receives the outputs of the defect 
detecting means 28 , 32 and 30, and outputs a defect 
detection signal DF when at least one of the defects has 
been detected. 

Referring to Fig. 3A and Fig. 3B, detection of a servo 
defect will be described. For recording data, a track which 
has a substantially uniform width Wt (the track is actually- 
circular or spiral, but the short part of the track 
illustrated can be treated as straight) is used. The track 
is formed of a continuous guide groove or the like. 
Consideration will be given to the case where the track is 
deformed at points X and Y. Such deformation may be caused 
due to dirt introduced during fabrication of a master disk 
or a substrate, irregular operation of a manufacturing 
machine, unevenness of a formed substrate, and other minor 
irregularities. Tracking control is performed such that a 
light spot follows the centerline 42c of the track shown by 
a chain line in Fig. 3A, and a tracking error signal Et 
shown in Fig. 3B is obtained. The tracking error signal Et 
is zero when the light spot is following the centerline 42c 
of the track. When the light spot deviates from the 
centerline 42c, the tracking error signal Et deflects either 
positively or negatively depending on the direction and the 
amount of deviation. Where there is a deformation of the 
track and the centerline 42c of the track is bent abruptly, 
since the light spot cannot follow the abrupt bending, the 
light spot deviates from the centerline 42c. 

At point X, there is a deflection in the tracking error 
signal Et due to the deformation of the track. At point Y, 
there is also a deflection in the tracking error signal Et 
due to meander of the track. If the tracking error 
tolerance limit Rtb shown by the broken line in Fig. 3B is 



20 



given as a reference for determining a servo defect, a servo 
defect is recognized at point Y. If a more strict tracking 
error tolerance limit Rta shown by the chain line in the 
figure is given, servo defects are recognized both at points 
X and Y. 

The tracking error tolerance limit Rta corresponds to 
the value of the tracking signal Et when the deviation of 
the light spot is one-fourth the tracking width Wt , and the 
tracking error tolerance limit Rtb corresponds to the value 
of the tracking signal Et when the deviation of the light 
spot is one-eighth the tracking width Wt . 

For instance, if the level Rta at the chain line is 
used as the defect criteria A, and the level Rtb at the 
broken line the figure is given as the defect criteria B, it 
is possible to perform servo defect determining process at 
two different levels. Incidentally, the recording track may 
not be a continuous groove. In a disk, such as a DVD-RAM, 
where user data recording areas are formed of lands and 
grooves, and no groove is formed at the header parts, which 
are formed of pre-pits only, it is sufficient to perform a 
servo defect detection only for areas where a groove 
continues. 

Servo defect detection can be performed with regard to 
a focus error signal, in the same way as the tracking error 
signal . 

Fig. 4A shows the configuration of a sector in a groove 
track in a DVD-RAM, and Fig. 4B shows the waveform of the 
signal reproduced from the sector shown in Fig. 4A. These 
drawings will be used for describing the detection of header 
defect. A recording sector of a DVD-RAM includes a header 
area having a sector address and the like at the beginning, 
followed by a data area for recording user data. The header 
area includes four ID's, indicated as ID1 to ID4 each 
containing address information representing a sector 



21 



address. In the sector shown in Fig". 4A, ID1 and ID2 are 
displaced one-half the track width Wt toward the outer 
periphery of the disk, and are shared with a sector in the 
outer adjacent land track, while ID3 and ID4 are displaced 
one-half the track width Wt toward the inner periphery of 
the disk, and are shared with a sector in the inner adjacent 
land track. 

In a land track not shown, ID1 and ID2 are displaced by 
one-half the track width Wt toward the inner periphery of 
the disk, and are shared with a sector in the inner adjacent 
groove track, and ID3 and ID4 are displaced by one-half the 
track width Wt toward the outer periphery of the disk, and 
are shared with a sector in the outer adjacent groove track. 
The waveform of the signal reproduced from the header area 
and the data area in a sector in a land track is also shown 
in Fig. 4B. 

The data area following the header is in a groove or a 
land, and contains a synchronous signal (SYNC), control 
information (CI), user data, and an error-correcting codes, 
and a buffer, which are recorded successively in this order. 
The control information CI consists of a small amount of 
information (such as the data number of the sector), other 
than user data. 

The size of user data, together with the control 
information, in one sector is 2 KB (kilobytes), and error- 
correcting coding is performed taking the user data and the 
control information of 32 KB in 16 successive sectors, as a 
unit, wherein error-correcting codes are added to the to 
form an ECC block. 

The error-correcting codes are distributed over the 16 
sectors . 

The sector address can be obtained if even one of the 
four ID's in a header is read correctly. In criteria B, if 
none of the four ID's is read correctly, the sector is found 



22 



i ■ ' 



have a header defect, and if two or more sectors within an 
ECC block are found to have a header defect, the ECC block 
is found to have a header defect. In criteria A, if not 
more than one of the four ID's is read correctly, the sector 
is found have a header defect, and if one or more sectors 
within an ECC block are found to have a header defect, the 
ECC block is found to have a header defect. 

A sector found to be non-defective according- to 
criteria A has at least two correctly readable ID's. This 
make it more likely that at least one ID will remain 
correctly readable even if the disk is later soiled or 
degraded, or transferred to another disk device. 

In this way, it is possible to perform header defect 
determination with two different levels. 

Fig. 5 shows the structure of an ECC block in a DVD- 
RAM. This drawing is used to describe the data defect 
detection. In the data recording means 24, the 23 KB data 
for 16 sectors are arranged in the form of matrix of 172 
bytes in the row direction by 192 bytes in the column 
direction. A 16-byte parity outer code PO in the column 
direction is added to each column, and then 10-byte parity 
inner code PI in the row direction is added to each row. 

Thus, a product code, which is a Reed-Solomon code, of 
182 bytes x 208 bytes is formed. 

When the data is recorded on the optical disk 2, the PO 
rows are interleaved with the other rows so that the error- 
correcting code bytes are evenly distributed over all 16 
sectors of the ECC block. 

At the time of reproduction, the data reproducing means 
16 rearranges the reproduced signal into a matrix of 182 
bytes x 208 bytes, and first detect and correct any errors 
of each row by means of the 10-byte inner code PI. The 
inner code PI is capable of correcting errors in up to five 
bytes per row, and detecting errors in up to ten bytes per 



23 



row. 

Next the 16-byte outer code PO is used to detect and 
correct any remaining errors. The outer code PO is capable 
of correcting- errors in up to 8 bytes per column, and 
detecting errors in up to 16 bytes per column. These error 
detecting and correcting capabilities can be improved by 
repeating the PI-PO error correction process, although the 
additional repetitions require additional circuitry and 
additional time. 

When a large number of errors are detected and 
corrected, it becomes likely that some of the corrections 
are wrong, the corrected data differing from the original 
data. Criteria A and B are therefore set, for example, as 
follows. In criteria A, a row is considered to have a data 
defect if errors are detected in at least four bytes, which 
is close to the error-correcting limit of the PI code, and 
an ECC block Is considered to have a data defect if it has 
at least eight rows having a data defect. In less strict 
criteria B, a row is considered to have a data defect If 
errors are detected in at least eight bytes, which is close 
to the repeated error-correcting limit of the PI code, and 
an ECC block is considered defective if it has at least 
eight rows having a data defect. When an ECC block is 
considered to have a data defect, all sixteen of its 
constituent sectors are replaced. 

In this way, it is possible to perform data defect 
determination with two different levels. 

In FIG. 5, row three has errors in four bytes, 
indicated by x's. This row is deemed to have a data defect 
under criteria A, but not under criteria B. 

In this way, the presence or absence of defect in each 
sector can be determined with respect to each of the servo 
defect, the header defect, and the data defect, according to 
the defect criteria supplied to each defect detecting means. 



24 



Fig. 6 summarizes the defect criteria A and B described 
above described as examples for the respective defects. The 
set of criteria A are stored in the criteria storing means 
34 while the set of criteria B are stored in the criteria 
storing means 36. It is then possible to switch between the 
two levels of criteria A and B by means of the criteria 
selecting means 38, according to the criteria setting signal 
CS . 

In the case of recording computer data, a high 
reliability is required so that the data once recorded are 
not lost or changed. For this reason, verifying 
reproduction is often effected at the time of recording. 
Accordingly , 

during recording and during verification production, the 
strict criteria A is applied to ensure that the correct data 

is recorded. 

In contrast, in the case of audio or video data, 
continuous recording at a high transfer rate is required. 
Accordingly, verifying reproduction is often omitted, 
ignoring data defects. Even if some defects occur during 
recording, as long as occurrence of the defects is of such a 
degree that the defects can be corrected or concealed later 
at the time of reproduction, it is preferable to continue 
recording operation ignoring the defects, since it will 
improve the performance and the operability as a recorder. 
For this reason, the criteria set for servo defects and 
header defects are set at a less strict level at which the 
recorded data can be corrected or concealed. 

When the two different defect criteria A and B 
available, the strict criteria A is used for recording 
computer data, while the less strict criteria B is used for 
recording audio or video data. 

There are situations where more than two different 
levels of reliability are required depending on types of 



25 



data to be recorded. For instance, there is a situation 
where three different levels are required, one for recording- 
computer data, another for recording important audio or 
video data, and the last one for recording normal audio or 
video data. In such a situation, as shown in Fig. 7, 
provision Is made to enable switching among three different 
defect criteria A, B, and C. Criteria A and B are the same 
as those described with reference to Fig. 6, and are used 
for recording computer data and for recording normal audio 
or video data, respectively. 

The criteria C is used for recording important audio or 
video data, and therefore, it has strictness intermediate 
between the criteria A and B. In the criteria C, the 
allowable deviation in tracking error is one-sixth the track 
width Wt, and an ECC block is found to have a header defect 
if all four ID'S are unreadable in any one sector. 
Regarding data defects, criteria C and A are the same. 

To use the three different sets of defect criteria, the 
defect determining means 12 should have an additional 
criteria storing means, in addition to the members shown in 
Fig. 2, and the criteria selecting means 38 should be able 
to select among the criteria A, B and C supplied from the 
above-mentioned additional criteria storing means, as well 
as the criteria storing means 34 and 36 in Fig. 2, in 
accordance with the criteria setting signal CS . 

Fig. 8 shows another embodiment of the defect 
determining means 12. The configuration of Fig. 8 Is 
different from the configuration of Fig. 2 in that the 
criteria storing means 34 and 36, and the criteria selecting 
means 38 which makes selection according to the criteria 
selecting signal CS shown in Fig. 2 are replaced with a 
defect setting and storing means 46 which makes setting 
according to the criteria selecting signal CS . 

The defect criteria to be applied is supplied from a 



26 



host device (not shown) through an interface to the drive 
control means 14. In response, the drive control means 14 
generates a criteria setting signal CS specifying the 
criteria . 

In the defect determining means 12 of Fig. 2, the 
defect criteria stored in the respective criteria storing 
means are fixed. However, in practical use, it may be 
desirable that the host device which controls the disk 
device (recording device) can flexibly vary the criteria so 
as to optimize the reliability and the transfer rate, 
depending on the nature, type, characteristics, and the 
degree of importance of the data to be recorded. For 
instance, a countermeasure for errors may be provided in the 
application software or file system. That is, error 
correcting coding may be applied before transmitting the 
data to the disk device at a predetermined rate. In this 
case, the defect management at the disk device is not so 
important, and the capability of continuous real-time 
recording at a high data transfer rate may be important. 

The embodiment described above can meet with these 
requirements . 

An embodiment of procedure followed in setting a defect 
criteria will be described with reference to Fig. 9. First, 
the host device sets the defect criteria to be used, 
according to type or contents of the data to be recorded. 
Then, a command for setting the criteria is sent from the 
host device to the disk device (drive). The disk device 
selects or sets the criteria upon reception of the command 
accordingly. In the system shown in Fig. 2, the command 
sent from the host device to the disk device is one for 
merely specifying selection between the criteria A and B. 
In the system shown in Fig. 8 in which the defect criteria 
can be set, the system is so configured that the defect 
criteria can be set arbitrarily at the host device, and the 



27 



command indicates the defect criteria set at the host 
device. Details of the command for setting- the defect 
criteria may be one which will be described later with 
reference to Fig:. 11, in which the defect criteria control 
information can select one among a plurality of criteria 
independently, for each of the servo defect, header defect, 
and data defect. 

The host device then sends a recording- command tog-ether 
with the data to be recorded. Upon reception of the 
command, the disk device records data in the specified 
sectors, and performs the defect management using: the defect 
criteria set in the manner described above, and reports the 
results of the defect management to the host device. The 
host device terminates a series of recording when it 
confirms that recording has been completed correctly. If 
the recording has been done incorrectly, a predetermined 
process (re-writing or informing the user) for dealing with 
the incorrectness is carried out. 

According to the procedure of Fig. 9, the host device, 
which knows the contents of the data to be recorded, sets 
the defect criteria finely optimized according to the type 
or contents of the data. It is therefore possible to 
provide flexibility for obtaining an optimum combination of 
reliability and transfer rate according to the intended use 
of the data. 

Fig. 10 shows another embodiment of a procedure 
followed for setting a defect criteria. In this embodiment, 
a command which sets a defect criteria and also instructs 
data recording is sent. First, the host device determines a 
defect criteria to be used in accordance with the type or 
contents of the data to be recorded, and then prepares the 
data to be recorded. This order may be reversed. 

Then, the host device sends the recording command which 
also sets the defect criteria, to the disk device. In 



28 



accordance with the designated defect criteria, the disk 
device selects or sets the criteria. The designation of the 
setting sent from the host device to the disk device may be 
one for specifying selection among a plurality of preset 
criteria (such as between the criteria A and B) . or one for 
setting an arbitrary criteria. 

The disk device records the data received together with 
the command, on the disk, while performing defect management 
in accordance with the defect criteria which has been set as 
described above, and informs the host device of the result. 
According to this embodiment, it is possible to obtain an 
optimum combination of reliability and transfer rate 
depending on the intended use of the disk, as in other 
embodiments described earlier. Moreover, because the number 
of commands transferred is reduced, the overhead is reduced, 
and the possibility of the transfer rate becoming lowered is 
reduced . 

A manner of recording control information representing 
the defect criteria designated at the time of data 
recording, in every sector on a disk will now be described. 
Fig. 11 shows the configuration of a defect criteria control 
information. With this configuration, one of four different 
criteria can be specified for each of the servo defect, the 
header defect and the data defect independently, by using 
one byte. 

The most-significant bit b7 indicates the mode of 
designation of the defect criteria. If the value of bit b7 
is "1", the mode designated by other bits of the control 
information byte is used, while if the value is "0" the 
default criteria which the disk device has is used ignoring 
the other bits of the control information byte. 

The next bit b6 indicates the range within which the 
defect criteria should be applied. If the value of bit b6 
is "1", the mode set by other bits in the control 



29 



information byte of are applied for each unit of recording:, 
e.g., each sector or block. If the value of bit b6 is "0" 
the same criteria is to be applied over the entire surface 
of the disk. 

The next two bits (b5 and b4) indicate the criteria 
applied for the servo defect, among the four criteria. If 
the combined value of bits b5 and b4 are "11" the tracking 
error tolerance above which the servo defect is recognized 
is one-forth the track width Wt. If the combined value is 
"10" the tolerance is one-sixth the track width Wt . If the 
combined value is "01" the tolerance is one-eighth the track 
width Wt. If the combined value is "00" the tolerance is 
one-tenth the track width Wt . 

The next two bits b3 and b2 indicate the defect 
criteria to be applied for the header defect, among the four 
criteria. If the combined value of the bits b3 and b2 is 
"11" the ECC block is found to have a header defect if all 
four ID'S are unreadable at two or more of its sectors. If 
the combined value is "10" the ECC block is found to have a 
header defect if three or more ID's are unreadable at two or 
more of its sectors. If the combined value is "01" the ECC 
block is found to have a header defect if all four ID's are 
unreadable at one or more of its sectors. If the combined 
value is "00" the ECC block is found to have a header defect 
if three or more ID's are unreadable at one or more of its 
sectors . 

The last two bits bl and bO indicate the defect 
criteria to be applied for the data defect, among the four 
criteria. If the combined value of the bits bl and bO is 
"11", the ECC block is found to have a data defect if at 
least 16 of its rows have errors in at least 8 bytes each. 
If the combined value is "10". the ECC block is found to 
have a data defect if at least 8 of its rows have errors in 
at least 8 bytes each. If the combined value is "01", the 



30 



ECC block is found to have a data defect if at least 8 of 
its rows have errors in at least 4 bytes each. If the 
combined value "00", the ECC block is found to have a data 
defect if at least 6 of its rows have errors in at least 4 
bytes each. 

The above described defect criteria control information 
can be located in each sector which constitutes a minimum 
unit of recording. In a DVD -RAM , a one-byte area may be 
reserved in the control information area located at the 
beginning of the data area shown in Fig. 4. The criteria 
may be set for each sector separately. The same defect 
criteria control information may be set in all the sectors 
within the same ECC block, or in predetermined sectors, so 
that the defect criteria control information is repeatedly 
recorded, and the range within which the same defect 
criteria should be applied may be made to coincide with the 
unit of error correction (ECC block) . 

The provision for enabling setting the finely optimized 
criteria improves the utility for the user in multimedia 
applications in which the audio or video data and computer 
data are intermixed with each other. It should be noted 
that the defect criteria to be applied to the respective 
data can be switched at the system (host device) depending 
on the contents of the data, and it is possible to realize a 
flexibility for obtaining the optimum combination of the 
reliability and transfer rate. 

It is possible to pre-select a defect criteria to be 
used in recording on a disk, and record the criteria as 
defect criteria control information on the disk, before the 
disk is used. Fig. 12 shows an example of arrangement of 
control information areas, and a data recording region 
including user areas and spare areas , and arrangement of 
defect criteria control information in the control areas. 
The data recording region is divided into groups, each of 



31 



which includes a user area and a spare area. The control 
information areas are disposed near the inner and outer 
peripheries of the disk, and the same control information is 
recorded on the respective control information areas. 

In a known example, a defect management method is 
recorded in a control information area. In contrast, 
according to this embodiment, defect criteria control 
information is stored in a control information area. At the 
time of starting a disk, the disk device reads the defect 
criteria control information to know the defect criteria. 
If the defect criteria suitable for the intended use, such 
as computer data, audio or video data, or the like is 
recorded, the defect determination according to the defect 
criteria can be made. 

If one bit is provided in the control information area 
for recording the defect criteria control information, it is 
possible to record two sets of defect criteria, and 
selectively use them. For recording three or four sets of 
defect criteria, and using them selectively, two bits should 
be provided in the control information area. If one byte is 
provided in the control information area, it is possible to 
select one of the criteria for each of the servo defect, 
data defect and header defect, and to specify a combination 
of specific defect criteria for the respective types, as 
described with reference to Fig. 11. 

With such a provision, if the information is recorded 
once at the time of initialization of the disk, the defect 
criteria can be applied to all the data thereafter recorded 
on the disk. It is therefore possible to eliminate to need 
to set the defect criteria each time the data is recorded. 
Accordingly, the recording can be effected at a high speed, 
and in a simple manner. 



32 



CLAIMS: 



1 . A recording device controller comprising: 

means for determining defect detection criteria applied according to 
the type of data to be recorded; and 

means for issuing a command for setting the determined defect 
detection criteria in a recording device. 

2. A recording device controller comprising: 

means for deterrnining defect detection criteria applied according to 
the type of data to be recorded; and 

means for issuing a single command for instructing that the 
determined defect detection criteria be set in a recording device and that 
recording of data be carried out. 

3. The controller according to claim 1 or claim 2, wherein said command 
is of a structure by which the defect detection criteria can be designated 
independently for a plurality of kinds of criteria items. 

4. A recording device controller comprising: 

means for determining information relating to the type of data 
recorded in accordance with the type of data recorded; and 

means for issuing a command for transferring the information relating 
to the type of data recorded that has been determined to a recording device. 

5. A recording device controller comprising: 

means for determining information relating to the type of data 
recorded in accordance with the type of data recorded; and 

means for issuing a single command instructing that the information 
relating to the type of data recorded that has been determined be transferred to 
a recording device, and that the recording of the data be carried out. 



33 



6. The controller according to claim 4 or claim 5, wherein the 
information relating to the type of data recorded is a flag designating a 
method of defect processing for the data recorded. 

5 

7. A method of managing defects on an optical disk used for recording 
data, comprising the steps of 

determining a criteria for detecting said defects according to the type 
of data for_ which defects are to be detected; and 
10 detecting said defects using said criteria when data is recorded on or 

reproduced from said disk. 

8. A disk device for accessing data on an optical disk, comprising: 
means for determining a criteria for detecting said defects according to 

1 5 the type of data for which defects are to be recorded; and 

means for detecting said defects using said criteria when data is 
recorded on or reproduced from said disk. 

9. An optical disk for recording data, comprising an area storing criteria 
20 control information specifying criteria to be used for detecting defects for data 

recorded on or reproduced from the disk. 

10. A disk recording and/or reproducing device comprising means for 
applying one of a plurality of predetermined criteria for recording and/or 

25 reproducing data according to the type of data to be recorded and/or 
reproduced. 



34 



Amendments to the claims have been Wed 3 s follows 



35 

CLAIMS: 

1 . A disk recording device controller comprising: 

means for determining defect detection criteria applied according to 
the type of data to be recorded; and 

means for issuing a command for setting the determined defect 
detection criteria in a recording device. 

2. A disk recording device controller comprising: 

means for determining defect detection criteria applied according to 
the type of data to be recorded; and 

means for issuing a single command for instructing that the 
determined defect detection criteria be set in a recording device and that 
recording of data be carried out. 

3. The controller according to claim 1 or claim 2, wherein said command 
is of a structure by which the defect detection criteria can be designated 
independently for a plurality of kinds of criteria items. 

4. A disk recording device controller comprising: 

means for determining information relating to the type of data 
recorded in accordance with the type of data recorded; and 

means for issuing a command for transferring the information relating 
to the type of data recorded that has been determined to a recording device to 
determine defect detection criteria. 

5. A disk recording device controller comprising: 

means for determining information relating to the type of data 
recorded in accordance with the type of data recorded; and 

means for issuing a single command instructing that the information 
relating to the type of data recorded that has been determined be transferred to 



2>C 



a recording device to determine defect detection criteria, and that the 
recording of the data be carried out. 

6. The controller according to claim 4 or claim 5, wherein the 
information relating to the type of data recorded is a flag designating a 
method of defect processing for the data recorded. 

7. A method of managing defects on an optical disk used for recording 
data, comprising the steps of 

determining a criteria for detecting said defects according to the type 
of data for which defects are to be detected; and 

detecting said defects using said criteria when data is recorded on or 
reproduced from said disk. 

8. A disk device for accessing data on an optical disk, comprising: 
means for determining a criteria for detecting said defects according to 

the type of data for which defects are to be recorded; and 

means for detecting said defects using said criteria when data is 
recorded on or reproduced from said disk. 

9. An optical disk for recording data, comprising an area storing criteria 
control information specifying criteria to be used for detecting defects for data 
recorded on or reproduced from the disk. 

10. A disk recording and/or reproducing device comprising means for 
applying one of a plurality of predetermined criteria for recording and/or 
reproducing data according to the type of data to be recorded and/or 
reproduced. 




& ^ The % 

• Patent ■ 
Office 



3- 



INVESTOR IN PEOPLE 



Application No: 
Claims searched: 



GB 0025335.1 
All 



3>T Examiner: 

Date of search: 



Donal Grace 
22 March 2001 



Patents Act 1977 

Search Report under Section 17 



Databases searched: 



UK Patent Office collections, including GB, BP, WO & US patent specifications, in: 
UKCKEd.S): G5R(RB27, RB33) 
Int CI (Ed.7): G11B 20/12, 20/18 
Other: Online: EPQDOC; JAPIO; WPI . . 



Docum 

Category 


tents consiuei cu w ^ »v,*w ^ . j 

Identity of document and relevant passage 


Relevant 
to claims 


X 


US 5237553 (FUKUSHIMA et al) see column 4 lines 19 to 49 


9 



X Document indicating lack of novelty or inventive step 
Y Document indicating lack of inventive step if combined 
with one or more other documents of same category. 

&, Member of the same patent family 



A Document indicating technological background and/or s*te of the art. 
P Document published on or after the declared priority date but before the 

filing date of this invention. _ 
E Patent document published on or after, but with priority date earlier 

than, the filing date of this application. 



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