Skip to main content

Full text of "USPTO Patents Application 10670332"

See other formats


WORLD INTELLECTUAL PROPERTY ORGANIZATION 
International Bureau 




PCT 

INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) 



(51) International Patent Classification 6 : 

G11B 7/00, 7/125, 7/007, 7/013, 20/12 



Al 



(11) International Publication Number: WO 96/30902 

(43) International Publication Date: 3 October 1996 (03.10.96) 



(21) International Application Number: PCT/GB95/02858 

(22) International Filing Date: 7 December 1995 (07.12.95) 



(30) Priority Data: 

08/414,825 



31 March 1995 (31.03.95) 



US 



(71) Applicant: INTERNATIONAL BUSINESS MACHINES 
CORPORATION [US/US]; Old Orchard Road, Armonk, 
NY 10504 (US). 

(71) Applicant (for MC only): IBM UNITED KINGDOM LIMITED 

[GB/GB]; North Harbour, P.O. Box 41, Portsmouth, Hamp- 
shire P06 3AU (GB). 

(72) Inventors: KULAKOWSKI, John, Edward; 7541 East Knoll- 

wood Place, Tucson, AZ 85715 (US). McDOWELL, Jud- 
son, Allen; 793 East Hardy, Tucson, AZ 85715 (US). RU- 
BIN, Kurt, Allan; 2377 Susan Drive, Santa Clara, CA 95050 
(US). 

(74) Agent: LING, Christopher, John; IBM United Kingdom Lim- 
ited, Intellectual Property Dept., Hursley Park, Winchester, 
Hampshire S021 2JN (GB). 



(81) Designated States: BR, CN, CZ, HU, KR, PL, RU, SG 
European patent (AT, BE, CH, DE, DK, ES, FR, GB, GR 
IE, IT, LU, MC, NL, PT, SE). 



Published 

With international search report. 



(54) Title: SPARE AND CALIBRATION SECTOR MANAGEMENT FOR OPTICAL WORM MEDIA 

(57) Abstract 

The present invention provides effi- 
cient management of calibration and spare 
sectors on a banded optical write-once, read- 
many (WORM) disk. A portion of each 
band on the disk includes a user data area 
and a reserved area. Sectors in the reserved 
area are usable either as spare sectors, re- 
placing defective sectors in the user area, 
or as calibration sectors, for use when the 
laser write -power level is calibrated. Sec- 
tors preferably are used for sparing from one 
end of the reserved area while sectors are 
used for calibration from the opposite end. 
A common overflow reserved area can also 
be provided for use if all of the sectors in 
one or more primary reserved areas associ- 
ated with any of the bands have been ex- 
hausted. 




FOR THE PURPOSES OF INFORMATION ONLY 



Codes used to identify States party to the PCT on the front pages of pamphlets publishing international 
applications under the PCT. 



AM 


Armenia 


GB 


United Kingdom 


MW 


Malawi 


AT 


Austria 


GE 


Georgia 


MX 


Mexico 


AU 


Australia 


GN 


Guinea 


NE 


Niger 


BB 


Barbados 


GR 


Greece 


NL 


Netherlands 


BE 


Belgium 


HU 


Hungary 


NO 


Norway 


BF 


Burkina Faso 


IE 


Ireland 


NZ 


New Zealand 


BG 


Bulgaria 


IT 


Italy 


PL 


Poland 


BJ 


Benin 


JP 


Japan 


PT 


Portugal 


BR 


Brazil 


KE 


Kenya 


RO 


Romania 


BY 


Belarus 


KG 


Kyrgystan 


RU 


Russian Federation 


CA 


Canada 


KP 


Democratic People's Republic 


SD 


Sudan 


CF 


Central African Republic 




of Korea 


SE 


Sweden 


CG 


Congo 


KR 


Republic of Korea 


SG 


Singapore 


CH 


Switzerland 


KZ 


Kazakhstan 


SI 


Slovenia 


a 


Cote d'l voire 


LI 


Liechtenstein 


SK 


Slovakia 


CM 


Cameroon 


LK 


Sri Lanka 


SN 


Senegal 


CN 


China 


LR 


Liberia 


sz 


Swaziland 


CS 


Czechoslovakia 


LT 


Lithuania 


TD 


Chad 


CZ 


Czech Republic 


LU 


Luxembourg 


TG 


Togo 


DE 


Germany 


LV 


Latvia 


TJ 


Tajikistan 


DK 




MC 


Monaco 


TT 


Trinidad and Tobago 


EE 


Estonia 


MD 


Republic of Moldova 


UA 


Ukraine 


ES 


Spain 


MG 


Madagascar 


VG 


Uganda 


FI 


Finland 


ML 


Mali 


US 


United States of America 


FR 


France 


MN 


Mongolia 


UZ 


Uzbekistan 


GA 


Gabon 


MR 


Mauritania 


VN 


Viet Nam 



WO 96/30902 



PCT/GB95/02858 



1 



SPARE AND CALIBRATION SECTOR MANAGEMENT FOR OPTICAL WORM 

MEDIA 

TECHNICAL FIELD OF THE INVENTION 

5 

The present invention relates to optical storage devices, and in 
particular, to management of spare and calibration sectors in a write -once 
optical storage system. 

10 BACKGROUND OF THE INVENTION 

When information is recorded onto optical media, the laser power 
should be established at such a level as to provide well formed recording 
marks, whether the marks are represented by changes in the reflective 

15 polarization of a spot on a rewritable magneto -optical (MO) disk, by pits 

burned into the surface of an ablative write-once disk or by changes in 
reflectivity between amorphous and crystalline areas of a phase change 
(PC) disk. However, even if the laser power is fixed when an optical disk 
drive is manufactured, many factors can cause such a fixing to be less 

20 than optimum. For example, two pieces of media from different 

manufacturers, or even from different batches from the same manufacturer, 
may have slightly different characteristics and, therefore, react slightly 
differently to the application of the same laser power lever. Other 
factors which can affect the optimum laser power level include the age of 

25 the drive and media, the operating temperature of the drive, the 

temperature of the media and any temperature differential between the 
media and the drive, the extent of media contamination, changes in the 
laser spot size and any focus or tracking sensor offsets. 

30 As a result, techniques have been developed for drive 

self -calibration during use. In one such technique, a calibration pattern 
(which cannot be confused with user data) is recorded onto one or more 
sectors at varying laser power levels. The sector is read back and, based 
upon such parameters as readback signal amplitude, mark edge jitter, mark 

35 peak pulse position, mark- space asymmetry and mark length, the optimum 

laser power level is selected for recording operations. Calibration can 
be performed each time the drive is powered on, at predetermined internals 
or each time a verification operation fails, among others, when a 
calibration is performed on an MO disk (or other re-writable media), a 

4 0 sector previously used for calibration can be erased and reused. 

Consequently, only a few such sectors need to be available. In contrast, 
however, when a calibration is performed on a write-once, read many (worm) 
disk, a sector previously used for calibration cannot be reused. Many 
calibration sectors should be available when the disk is new. The 

45 requirement for many calibration sectors may be particularly acute for the 



WO 96/30902 



PCT/GB95/02858 



2 



recently proposed 130 mm 1.3 GB per side WORM media which uses a pulse 
width modulation (PWM) recording technique as compared to the currently 
common 130 mm 325 MB per side WORM media using a peak pulse modulation 
(PPM) recording technique. The four times increase in recording capacity 
5 is primarily due to the increase in recording density, decrease in mark 

size, and adoption of the PWM recording technique. PWM requires greater 
precision in mark- space writing because the transitions are used to encode 
the information. In addition, the PWM uses marks of varying lengths 
placing an additional demand on quality mark formation. All of these 

10 factors increase the need for use of optimum write power to form quality 

marks with precisely placed edges. In fact, in some operating 
environments, a drive may have to be calibrated each time a disk is 
mounted to achieve required data reliability and performance. it can be 
appreciated that if all of the calibration sectors are used, no further 

15 information can be recorded onto the disk because there is no longer the 

ability to ensure a proper laser write power level. 

When a recorded data sector is determined during verification to be 
defective, the data must be written to another sector. In one disk format 
20 configuration for WORM media, one or more regions of the disk are set 
aside as spare sectors to replace defective "primary" sectors. Again, 
however, if the spare sectors are exhausted, no further data can be 
reliably recorded. 

25 DISCLOSURE OF THE INVENTION 

In view of the foregoing, it is an object of the present invention 
to provide one or more areas on WORM media allocated to both calibration 
and spare sectors. 

30 

It is another object to provide an initialization process for WORM 
media to allocate areas on the media for both spare and calibration 
sectors . 

35 It is still a further object to provide an optical storage device 

for recording data onto WORM media with improved calibration and spare 
sector usage. 

Apparatus and method are provided for the efficient management of 
4 0 calibration and spare sectors on a banded optical write -once disk. Each 

band on the disk includes a user data area and a reserved area. Sectors 
in the reserved area are usable either as spare sectors, replacing 
defective sectors in the user area, or as calibration sectors, for use 
when the laser write -power level is calibrated. In one embodiment, spare 
45 and calibration sectors are not pre-assigned to separate and specific 



WO 96/30902 



PCT/GB95/02858 



3 



portions of the reserved area. Rather, sectors are used for sparing froi 
one end of the reserved area while sectors are used for calibration from 
the opposite end. Moreover, to avoid potential tracking difficulties, 
spare sectors are preferably used beginning at the lowest address in 
reserved area and calibration sectors are used beginning at the highest 
address . 



The number of sectors allocated to each reserved area is established 
when the media is initialized. For example, the media manufacturer can 
10 initialize the media before distribution giving the user no ability to 

adjust the allocation. When a disk is sold in an uninitialized state, the 
user can be given the option of choosing the relative size of the reserved 
area, or can be given a choice of several sizes, to adapt the media for a 
particular environment and pattern of usage* 

15 

In a further embodiment, a common overflow reserved area is provided 
for use if all of the sectors in one or more primary reserved areas 
associated with any of the bands have been exhausted. 

20 Each sector on the WORM disk contains a DMP (defect management 

pointer) area which is recorded when the sector is used. When a sector in 
the user data area of a band is recorded, the address of the sector is 
written in a first word of the DMP and the starting address of the 
reserved area serving the band is written in a second word; the laser 

25 power level used to write the sector is written in a third word, when a 

sector in the reserved area of a band is used as a replacement for a 
defective sector, the address of the spare sector is written in the first 
word of the DMP and the address of the defective sector is written in the 
second word; the laser power level used to write the spare sector is 

3 0 written in the third word. When a sector in the reserved area is used as 

a calibration sector, a write-power calibration pattern is written in the 
first two words and the power level which the calibration process 
determines to be optimum is written in the third word. 

35 A method is also provided for calibrating the drive during a multi- 

sector write operation. The first sector is recorded in the user data 
area of a particular band and then verified. If the verification is 
successful, the remaining sectors are recorded in the user data area. 
However, if the verification indicates that the laser write power is 

40 incorrectly set, a calibration is performed. Then, at the newly 

calibrated power levels the first sector is re- recorded as a spare sector 
in the reserved area and the remaining sectors are recorded in the user 
data area. 



WO 96/30902 



PCT/GB95/02858 



4 



The foregoing and other features and advantages of the inversion 
will be apparent from the following more particular description of 
preferred embodiments of the invention, as illustrated in the accompanying 
drawings . 

BRIEF DESCRIPTION OF THE DRAWINGS 

Figure 1 is a block diagram of an optical storage device of the 
present invent ion ; 

Figures 2 and 3 are simplified diagrammatic views of portions of a 
write -once optical disk of the present inventions- 
Figure 4A is a simplified diagrammatic view of a radial portion of 
15 the write-once optical disk; and 

Figure 4B is an enlarged view of a portion of one band of the write- 
once optical disk. 



10 



20 DETAILED DESCRIPTION OF THE INVENTION 



Figure 1 is a block diagram of an optical storage device of drive 2 
in which the present invention can be employed. The drive 2 can be a 
write-once device or can be a multi - function device having the capability 
25 of recording either WORM or re- writable media. For purposes of clarity, 

various components of the drive 2, including those which pertain only to 
re-writable operations, have been omitted from Figure 1 and will not be 
discussed. 



30 A write-once optical disk 10 is mountable on a spindle 14 for 

rotation by a spindle motor 16 under the control of a spindle controller 
18. Not shown is a loader mechanism by which the disk 10 is loaded into 
the drive 2 and lowered onto the spindle 14; when disk operations are 
completed, the loader mechanism reverses the process and ejects the disk 

35 from the drive 2. A headarm carriage 20 is movable radially relative to 

the disk 10 carrying an objective lens 22 for accessing data on any one of 
a large plurality of addressable tracks on the disk 10. The radial motion 
of the carriage 20 is controlled by a coarse actuator 24. 



40 A light beam (represented by the dashed line 26) from a laser 28 is 

directed to an optical signal processing portion 30, comprising various 
optical and opto- electrical elements 32, which directs the light 26 
through the lens 22 onto the surface of the disk 10. The laser 28 is 
controlled by a laser controller 34; focusing and tracking are performed 



WO 96/30902 



PCT/GB95/02858 



5 

by a fine actuator 36 controlled by focus and tracking circuits 3 8 with 
input from a relative position focus sensor 40. 

The drive 2 is interconnected through an input/output interface 42 
5 to a host device 44. Data to be recorded onto the disk 10 is transmitted 

by the host device 44 through the input/output interface 42 to data 
channels 46. Data read from the disk 10, after being converted from 
optical signals into electrical signals, is passed through the data 
channels 46 and transmitted through the input/output interface 42 to the 
10 host device 44. A microprocessor 48, which includes (or is interconnected 

with) a memory store 50, is interconnected to components of the drive 2 
and directs the operation thereof. 

Figure 2 is a simplified diagrammatic view of the WORM disk 10 

15 formatted in accordance with the present invention. Beginning at the inner 

diameter (ID) 102 and extending radially toward the outer diameter (OD) 
104 is a control area comprising a phase-encoded part (PEP) 106, a 
standard format part (SFP) 108 and a manufacturer area (MFG) 110. 
Duplicates (not shown) of the SFP and MFG are located at the OD 104. The 

20 disk 10 has a single spiral track extending between the ID 102 and the OD 
104 (although the spiral can instead extend in the reverse direction) 
which is divided into several radial bands 112-117 (or, alternatively, 
comprises a single band) , each band having a plurality of addressable 
tracks and each track having a plurality of sectors. Ellipsis 114 

25 represent a plurality of bands between bands 113 and 115. in one proposed 

4X WORM format, the disk 10 has thirty- four bands numbered from the 
outside (band 0) toward the inside (band 33); tracks and sectors are 
similarly given addresses from outside to inside. However, this 
configuration is given by way of example only and not as any limitation of 

30 the present invention. 

Figure 3 is a simplified diagrammatic view of a portion of one 
exemplary band 113 having a plurality of sectors, only a small number of 
which (represented by sectors 130-136, 140 and ellipsis 138) are 

35 illustrated. A typical sector, such as sector 140, includes a header area 

144 and a user data 142 having a defect management pointer (DMP) 146. The 
sectors in the band 113 are grouped into a user data area 160 and a 
reserved area 170. The number of sectors in each band is established when 
the disk 10 is manufactured and increases from the inner band to the outer 

40 band. However, as will be discussed below, in one embodiment the ratio of 

reserved sectors to user sectors in a band can be determined for each disk 
by the user when the disk is initialized, thereby establishing starting 
addresses for each reserved area 170. Alternatively, the ratio can be 
fixed at the time of disk manufacture and not be user configurable. 



WO 96/30902 



PCT/GB95/02858 



6 

The DMP 146 of a sector, such as sector 140, in the user area 160 
contains three four -byte words which are recorded during a write - 
operation. The first word contains the address of the sector 140. The 
second word contains the starting address of the reserved area 170 and 
5 serves as a general pointer to the reserved area 170, although not to a 

particular sector in the reserved area 170. The third word contains the 
value of the laser power which was used to write the sector 140. 

Sectors in the reserved area 170, such as sector 130, also have a 
10 DMP area, although the contents of the DMP will vary depending upon the 

use of the sector as a spare sector or a calibration sector, as will be 
explained . 

When data is recorded to the sector 14 0 during a write operation, 
15 the three words are recorded to the DMP 146. If the readability of the 

sector 140 cannot be verified, the data is recorded in an unused sector, 
such as the sector 132, (hereinafter, the spare sector) in the reserved 
area 170. The spare sector is located by the laser beam 26 scanning the 
reserved area 17 0 for the next available blank sector. Contemporaneously 
20 with recording the data, the address of the spare sector 132 is recorded 
in the first word of the DMP of the spare sector 132 and the address of 
the defective sector 140 which is being replaced is recorded in the second 
word. The laser power level is recorded in the third word. 

25 When the laser write -power is to be calibrated as determined by the 

microprocessor 48 based upon predetermined criteria, such as the number of 
sectors which cannot be verified, the microprocessor 4 8 in the drive 2 
directs the laser beam 26 to an unused sector, such as the sector 13 0, 
(hereinafter, the calibration sector) of the reserved area 170. The 

30 calibration sector is located by the laser beam 26 scanning the reserved 
area 170 for the next available blank sector. A pattern of marks is 
recorded in the first and second words of the DMP , each mark being 
recorded with a different laser power setting. In one embodiment, the 
entire range of write-power levels is used to record the calibration 

35 marks. The drive 2 is then placed in a mark quality verification mode, 

the calibration marks are "read" back and the microprocessor 48 determines 
which power level produces the best mark quality. The laser power setting 
used to write the calibration mark is recorded in the third word of the 
DMP at the same time the calibration marks are recorded. Alternatively, 

40 the calibration marks recorded at a selected 

power level can be verified as to mark quality immediately after they are 
written and, if the marks satisfy the mark quality criteria, the power 
level used to record the mark is recorded in the third word of the DMP 
area of the calibration sector and no additional calibration marks are 

45 written. If, however, the mark does not satisfy the mark quality 



WO 96/30902 



PCT/GB95/02858 



7 



criteria, additional calibration marks are recorded at a different power 
level and the mark quality verified. As an alternative to using the 
entire calibration sector for a single power calibration test, the sector 
can be divided into "micro- sectors" . A single micro-sector can be used 
5 for each calibration test and the power level recorded in the DMP area of 

the micro-sector. It will be appreciated that this alternative method of 
determining an appropriate or optimum laser power level will generally use 
less space in the reserved area 170 than the former method and it may be 
possible to use a single calibration sector for more than one calibration 
10 operation. 

As previously noted, it is preferable that the laser power be 
calibrated as infrequently as possible in order to prevent premature 
exhaustion of calibration sectors. Consequently, a default power level 

15 can be programmed into the microprocessor 48. If during a recording 

operation, a predetermined number of sectors cannot be verified, 
indicating that the laser power level may be incorrect, the microprocessor 
can initiate the calibration procedure. In another embodiment for use 
during a multi- sector write operation, the first sector is recorded and an 

20 attempt is made to verify its readability. if the verification is 

successful, indicating a correct power level, the remaining sectors are 
recorded at the same level. However, if the verification is unsuccessful, 
the microprocessor 4 8 determines that a calibration is to be performed. 
Then, the first sector is re -written to a spare sector in the reserved 

25 area 170 and the remaining sectors are recorded in the user area 160 at 

the newly calibrated power level. Moreover, when the remaining sectors 
are verified, the write power level can be readjusted if necessary in 
preparation for the next write command, thereby further reducing the need 
to use another calibration sector. 

30 

The calibration pattern may consist of a 2T mark, a 6T space, a 4T 
mark and a 6T space repeated many times. Many patterns may be used as 
long as the written pattern allows for the separation of thermal effects 
of the written marks. The calibration pattern, if written at excessive 

35 write laser power, could produce excessively large marks that could affect 

the focus and tracking process, thus track following of laser beam 26 
would be faulty. In addition, a calibration sector may not contain error 
correction codes or resync characters and thus can not be differentiated 
reliability from a sector with a large defect if written with incorrect 

40 laser power levels, again arguing for separation. Finally, the use of 

micro-sectors will result in areas of a calibration sector being 
unrecorded and appearing as a large media defect, again arguing for 
separation. Consequently, calibration sectors should not be intermixed 
with spare sectors in the reserved area 170. An alternative 

45 implementation that would permit intermixing of spares and calibration 



WO 96/30902 



PCT/GB95/02858 



a 



sectors would make use of tables to identify the sectors in the reserved 
area used for spares and those used for calibration. Thus the need to 
read or track reliably over the data area of a calibration sector could be 
avoided. The disadvantage of this implementation is the consumption of 
5 valuable disk space by maintaining such tables on write-once media. Each 

time a sector is spared or a calibration section is written, the tables 
must be updated consuming additional space. Although it would be possible 
for one set of addresses in the reserved area 170 to be specifically 
allocated to spare sectors and a separate set of addresses specifically 

10 allocated to calibration sectors, such a predetermined and invariable 

allocation of space would not necessarily be suitable in all operating 
environments. For example, in an environment in which data is written to 
a disk relatively frequently, or in which disks are mounted/unmounted 
often, or in which only small amounts of data are recorded in a single 

15 operation, operating parameters can change often. in such a situation, 

re -calibration may be required frequently, exhausting the calibration 
sectors before consuming all of the data or spare sectors. On the other 
hand, when the operating environment generally consists of frequent 
recording of large blocks of data, the parameters may be more stable and 

20 fewer calibrations will be needed but possibly more spare sectors. 

Therefore, the allocation of sectors between spare and calibration sectors 
should preferably be performed dynamically. In the present invention, 
rather than allocating a particular portion of the reserved area 170 for 
sparing and the balance to calibration, it is preferred that spare sectors 

25 and calibration sectors be expended from opposite ends of the reserved 

area 170, as illustrated by the arrows in Fig. 4B. Moreover, because of 
the tracking problems associated with calibration sectors, it is preferred 
that the calibration sectors be used from the inner end (higher addresses) 
172 of the reserved area 17 0 towards the outer end (lower addresses) while 

3 0 the spare sectors be used from the outer end 174 toward the inner. Thus, 

the available space in the reserved area 170 is exhausted only when there 
are no free sectors remaining in the reserved area 17 0, regardless of the 
relative number of sectors used for sparing and calibration. 

35 The present invention provides a further area on the disk 2 for 

spare and calibration sectors to be used when the reserved area 170 of any 
band has been filled. A common overflow reserved area 118 is contained in 
the last band 117 along with the reserved area for the band 117 (Fig. 4A) . 
The last band 117 is a preferred location for the common overflow area 118 

40 because drive performance is typically the lowest in this band and it is 

desired not to employ a high performance area on the disk 10 for such a 
use. The common overflow area 118 is used in the same manner as the 
reserved area 170 but can contain spare and calibration sectors associated 
with more than one band. while there may not be a pointer in the primary 

45 reserved area 17 0 to the address of the common overflow area 118, the 



WO 96/30902 



PCT/GB95/02858 



9 



drive 2 can be programmed to seek to the common overflow area 118 in the 
event that it finds the primary reserved area 170 full or in the event 
that it fails to find in the reserved area 170 the spare sector as a 
replacement for a previously recorded for defective user sector. 
5 Alternatively, the drive 2 can be programmed to seek to the next available 

reserved area (that is, to the reserved area of the next band toward the 
ID 102) for calibration purposes if the reserved area of a particular band 
is full and seek to the common overflow area 118 for sparing (because the 
optimum laser power level may vary from band to band, it is preferable to 
10 perform a calibration as close as possible to the desired band) . 

As previously discussed, the size of each reserved area 170 can be 
established by the media manufacturer if the manufacturer initializes the 
media or can be established by the user. If the latter, the user 

15 determines approximately how many spare sectors and how many calibration 

sectors will be needed for the entire disk based upon the particular 
operating environment and conditions. The sum of the two is then 
allocated proportionally among the bands based upon the total number of 
sectors in each band (which can, in some disk formats, vary from band to 

20 band) . Alternatively, a default number can be provided and the user given 
the option of doubling or tripling the value when the disk 10 is 
initialized. The microprocessor 48 then calculates the beginning and 
ending addresses for each user data area 160 and each reserved area 170 
for each band, as well as the beginning and ending addresses for the 

2 5 common overflow area 118, and records this information in the disk 

structure table (DST) sector on the disk 10. The information in the DST 
enables the microprocessor to translate logical block addresses received 
from the host 44 into physical track and sector addresses on the disk 10. 



30 



WO 96/30902 



PCT/GB95/02858 



10 



CLAIMS 

1. A method of calibrating laser write power in an optical drive, 
comprising the steps of: 

5 

mounting a write-once optical disk in a drive unit, the disk having 
a plurality of recording bands, each band having a reserved area 
comprising calibration sectors and spare sectors, each band further having 
a user area comprising user data sectors ; 

10 

moving an optical head to a selected band; 

determining if the laser write power should be calibrated; 

15 if the laser write power should be calibrated, seeking to an unused 

first calibration sector in the reserved area of the selected band; 

establishing an information field in the first calibration sector; 

20 writing a write power calibration pattern in the first calibration 

sector; 

reading the write power calibration pattern from the first 
calibration sector; and 

25 

determining the write power value to be used for recording data onto 
user data sectors in the selected band of the optical disk. 

2. A method as claimed in Claim 1, further comprising the steps of, if 
30 there are no unused first calibration sectors in the reserved area of the 

selected band: 

seeking to an unused second calibration sector in a common overflow 
area of the disk; 

35 

establishing an information field in the second calibration sector; 

writing a write power calibration pattern in the second calibration 
sector ; 

40 

reading the write power calibration pattern from the second 
calibration sector; and 

determining the write power value to be used for recording data onto 
45 user data sectors in the selected band of the optical disk. 



WO 96/30902 



PCT/GB95/02858 



11 



10 



3. A method as claimed in Claim 1, further comprising the steps of: 

recording data onto a selected user data sector in the selected band 
at the determined write power value; 

verifying the data recorded onto the selected user sector; 

if said verification step fails, seeking to an unused first spare 
data sector in the reserved area of the selected band; 



establishing an information field in the first spare data sector; 
recording the data onto the first spare data sector; and 
15 verifying the data recorded onto the first spare data sector. 

4. A method as claimed in Claim 3, wherein: 

said step of seeking to an unused first calibration sector in the 
20 reserved area of the selected band comprises the step of seeking to an 

unused sector closest to a first end of the reserved area; and 

said step of seeking to an unused first spare data sector in the 
reserved area of the selected band comprises the step of seeking to an 
25 unused sector closest to a second end of the reserved area. 

5. A method as claimed in Claim 3, further comprising the steps of , if 
there are no unused first spare data sectors in the reserved area of the 
selected band: 

30 

seeking to an unused second data spare sector in a common overflow 
area of the disk; 

establishing an information field in the second spare data sector; 
35 recording the data onto the second spare data sector; and 

verifying the data recorded onto the second spare data sector. 

6. A method as claimed in Claim 5, wherein: 



said step of seeking to an unused first calibration sector in the 
reserved area of the selected band comprises the step of seeking to an 
unused sector closest to a first end of the reserved area; 



WO 96/30902 



PCT/GB95/02858 



12 

said step of seeking to an unused first spare data sector in the 
reserved area of the selected band comprises the step of seeking to an 
unused sector closest to a second end of the reserved area; 

said step of seeking to an unused second calibration sector in the 
common overflow area comprises the step of seeking to an unused sector 
closest to a first end of the common overflow area; and 

said step of seeking to an unused second spare data sector in the 
common overflow area comprises the step of seeking to an unused sector 
closest to a second end of the common overflow area. 

7. A method as claimed in Claim 1, further comprising the steps of: 

recording first data onto a first selected user data sector in the 
selected band at a first write power value; 

verifying the first data recorded onto the first selected user 
sector; 

if said verification step fails, seeking to an unused first 
calibration sector in the reserved area of the selected band; 

performing said establishing, writing, reading and determining 

steps; 

seeking to an unused first spare data sector in the reserved area of 
the selected band; 

establishing an information field in the first spare data sector; 
recording the first data onto the first spare data sectors- 
verifying the first data recorded onto the first spare data sector; 
moving the optical head in a radial direction to the selected band; 

and 

recording the balance of the data to second sectors in the selected 
band at the determined write power value. 

8. A write-once optical disk, comprising: 

a spiral track extending between inner and outer radial positions, 
said spiral track having a plurality of logical tracks grouped into a 
plurality of data bands; 



WO 96/30902 



PCT/GB95/02858 



13 



a predetermined plurality of primary data sectors in each of said 
data bands; and 

a reserved area in each of said data bands, said reserved area 
having a predetermined plurality of sectors, each of which is usable as 
either a spare sector or a calibration sector. 

9. The write -once optical disk of Claim 8, further comprising a common 
overflow area having a predetermined plurality of sectors, each of which 
is usable for either sparing or calibration. 

10. The write-once optical disk of Claim 9, wherein: 

said common overflow area has a first end and a second end; and 

during a recording operation, usage of sectors in said common 
overflow area for sparing is in a direction from an unused sector closest 
to said first end toward said second end and usage of sectors in said 
common overflow area for calibration is in an opposite direction from an 
unused sector closest to said second end toward said first end. 

11. The write-once optical disk of Claim 8, wherein: 

each said reserved area has a first end and a second end; and 

during a recording operation, usage of sectors in said reserved area 
for sparing is in a direction from an unused sector closest to said first 
end toward said second end and usage of sectors in said reserved area for 
calibration is in an opposite direction from an unused sector closest to 
said second end toward said first end. 

12. The write -once optical disk of Claim 8, wherein sectors in a band 
include a header area and a user data area. 

13. The write-once optical disk of Claim 12, wherein said data area of a 
primary data sector comprises: 

a first portion in which an address of said primary data sector is 
recordable; 

a second portion in which an address of said reserved area of said 
band is recordable; and 

a third portion in which a laser calibration value is recorded. 



WO 96/30902 



PCT/GB95/02858 



14 

14. The write-once optical disk of Claim 12, wherein said data area of a 
spare sector comprises: 

a first portion in which an address of said spare sector is 
recordable; 

a second portion in which an address of a defective primary data 
sector in said band is recordable; and 

a third portion in which a laser calibration value is recorded. 

15. The write-once optical disk of Claim 12, wherein said data area of a 
calibration sector comprises: 

a first portion in which at least a portion of a calibration pattern 
is recordable; and 

a second portion in which a laser calibration value is recorded. 

16. A system for recording data onto an optical WORM disk, the disk 
having a plurality of data bands, each band having a first plurality of 
sectors in a user area and a second plurality of sectors in a reserved 
area, the system having a loader mechanism, a spindle motor on which the 
optical disk is mountable, an interface for transmitting/receiving data 
and instructions to/from a host device, a laser light source, an optical 
head for recording/reading data to/from the optical disk, an actuator for 
moving said optical head, and a controller for directing operations of 
said loader mechanism, said spindle motor, said interface, said optical 
head and said actuator, characterised in that the system further 
comprises : 

a processor for determining when a laser write-power calibration is 
to be initiated; 

means for directing the light beam from said laser onto a first 
predetermined sector in said reserved area if calibration is to be 
initiated; 

means for writing a calibration pattern in said predetermined 
sector; 

means for reading the calibration pattern and determining an 
adjusted write-power level; 



WO 96/30902 



PCT/GB95/02858 



15 

means for setting the write-power level to the adjusted write-power 

level; 

means for recording first data on a predetermined data sector in 
said user area; 

means for verifying the first data; 

means for directing the light beam from said laser onto a second 
predetermined sector in said reserved area if the verification fails; and 

means for re-recording the first data onto said second predetermined 
sector. 

17. A data recording system as claimed in Claim 16, wherein: 

said means for directing the light beam onto the first predetermined 
sector in said reserved area comprises means for directing the light beam 
onto the first predetermined sector in a first end of said reserved area; 
and 

said means for directing the light beam onto the second 
predetermined sector in said reserved area comprises means for directing 
the light beam onto the second predetermined sector in a second end of 
said reserved area, opposite the first end. 

18. A data recording system as claimed in Claim 16, wherein said means 
for recording the first data in the predetermined data sector comprises 
means for recording an address of the predetermined data sector in a first 
word of the predetermined sector, recording an beginning address of said 
reserved area in a second word of the predetermined data sector and 
recording a laser write-power level in a third word of the predetermined 
data sector. 

19. A data recording system as claimed in Claim 16, further comprising: 

means for receiving an input from a user indicating the second 
plurality of sectors to be allocated to said reserved area of each band; 
and 

means for determining a beginning address and an ending address of 
each reserved area of each band. 



WO 96/30902 



PCT/GB95/02858 




FIG. 1 



10 




SUBSTITUTE SHEET (RULE 26} 



WO 96/30902 



PCT/GB95/028S8 




FIG. 2 




FIG. 4B 



118 

FIG. 4A 

SUBSTITUTE SHEE1 (RULE 26) 



116 



>1W 



INTERNATIONAL SEARCH REPORT 



Ir Clonal Application No 

PCT/GB 95/02858 



A. CLASSIFICATION OF SUBJECT MATTER. , „ „ 

IPC 6 G11B7/0O G11B7/125 G11B7/O07 G11B7/013 G11B20/12 



According to International Patent Classification (IPC) or to both national class ft cation and IPC 



B. FIELDS SEARCHED 



Minimum documentation searched (classification system followed by classification symbols} 

IPC 6 G11B 



Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched 



Electronic date base consulted during the international search (name of data base and, where practical, search terms used) 



C. DOCUMENTS CONSIDERED TO BE RELEVANT 



Category " 



Qua on of document, with indication, where appropriate, of the relevant passages 



Relevant to claim No. 



EP-A-0 442 566 (PHILIPS NV) 21 August 1991 

see column 1, line 1 - line 22 

see column 4, line 10 - line 16 

see column 6, line 38 - line 48 

see column 8, line 39 - line 49 

see column 13, line 49 - column 14, line 

12 

see column 14, line 42 - column 15, line 
32 

EP-A-0 577 214 (PHILIPS ELECTRONICS NV 
;IBM (US)) 5 January 1994 
see page 3, line 45 - line 55; figure 1 
see page 4, line 37 - line 40; figure 2 
see page 5, line 52 - line 54 



1-19 



1,8,16 



EP-A-0 555 065 (IBM) 11 August 
see page 18, line 45 - line 47 



1993 



1,8,16 



LU 



Further documents are listed in the continuation of box C. 



HI 



Patent family members arc listed in annex. 



* Special categories of a ted documents : 

*A* document defining the general state of the ait which is not 

considered to be of particular relevance 
*E* earlier document but published on or after the international 

filing date 

X* document which may throw doubts on pnonty daim(s) or 
which is a ted to establish the publication date of another 
citation or other special reason (as specified) 

*0* document referring to an oral disclosure, use, exhibition or 
other means 

*P* document published prior to the international filing date but 
Later than the pnonty date claimed 



"V later document published after the international filing date 
or pnonty date and not in conflict with the application but 
cited to understand the pnnapic or theory underlying the 
invention 

'X* document of particular relevance, the claimed invention 
cannot be considered novel or cannot be considered to 
involve an inventive step when the document is taken alone 

# Y* document of particular relevance; the d aimed invention 
cannot be considered to involve an inventive step when the 
document is combined with one or more other such docu- 
ments, such combination bang obvious to a person stalled 
in the art. 

'&' document member of the same patent family 



Date of the actual completion of the international search 



12 February 1996 



Date of mailing of the international search report 



- 2. W. 96 



Name and mailing address of the ISA 

European Patent Office, P.B. SKIS Patentlaan 2 
NL - 22*0 HV Rj)swi)k 
Td. ( * 3170) 34O.2040, Tx. 31 651 epo nl, 
Fax ( * 31-70) 340-3016 



Authonzcd officer 



Poth, H 



i PCT1SA.21CM 



) <J«Jy IW) 



page 1 of 2 



INTERNATIONAL SEARCH REPORT 



I: moral Application No 

PCT/GB 95/02858 



C.(Conanuauon) DOCUMENTS CONSIDERED TO BE RELEVANT 



Category ' 



Citation of document, with indication, where appropriate, of the relevant passages 



Relevant to claim No. 



x,p 



EP-A-0 404 251 (PHILIPS NV) 27 December 
1990 

see the whole document 

EP-A-0 404 249 (PHILIPS NV) 27 December 
1990 

see the whole document 

W0-A-95 22142 (PHILIPS ELECTRONICS NV 
; PHI LIPS NORDEN AB (SE)) 17 August 1995 
see claims 



1-19 



1-19 



1,8,16 



Form PCTTSX 210 (coAunuation of tftcond H>««l) (July IW) 



page 2 of 2 



INTERNATIONAL SEARCH REPORT 

Information on patent family members 



t iQonal Application No 

PCT/GB 95/02858 



Patent document 
cited in search report 



Publication 
date 



Patent family 
member(s) 



Publication 
date 



EP-A-0442566 



EP-A-0577214 



21-08-91 



05-01-94 



NL-A- 
DE-D- 
JP-A- 
US-A- 



9000327 
69115304 
4214208 
5072435 



CN-A- 
JP-A- 
US-A- 



1083252 
6223503 
5418773 



02-09-91 
25-01-96 
05-08-92 
10-12-91 



02-03-94 
12-08-94 
23-05-95 



EP-A-0555065 



11-08-93 



US-A- 
AU-B- 
AU-B- 
CA-A- 
CN-A- 
JP-A- 
NZ-A- 



5293565 
664061 
3100493 
2081179 
1075230 
6084287 
245391 



08-03-94 
02-11-95 
05-08-93 
05-08-93 
11-08-93 
25-03-94 
21-12-95 



EP-A-0404251 



27-12-90 



AT-T- 

AT-T- 

CN-A.B 

CN-A.B 

DE-D- 

DE-T- 

DE-D- 

DE-T- 

EP-A- 

HU-B- 

HU-B- 

JP-A- 

JP-A- 

NL-A- 

PL-B- 

SU-A- 

US-A- 

US-A- 



114855 
114856 
1048279 
1048945 
69014435 
69014435 
69014436 
69014436 
0404249 
208877 
210013 
3102679 
3034127 
9000328 
165214 
1796076 
5226027 
5303217 



15-12-94 

15- 12-94 
02-01-91 
30-01-91 
12-01-95 
01-06-95 
12-01-95 
14-06-95 

27- 12-90 

28- 01-94 
30-01-95 
30-04-91 

14- 02-91 

16- 01-91 
30-11-94 

15- 02-93 
06-07-93 
12-04-94 



EP-A-0404249 



27-12-90 



NL-A- 
AT-T- 
AT-T- 
CN-A.B 



9000328 
114855 
114856 

1048279 



16-01-91 
15-12-94 
15-12-94 
02-01-91 



Form PCT ISA. 31 • (jmmi faouly 



i) <July IMS) 



page 1 of 2 



INTERNATIONAL SEARCH REPORT , — 




itional Application No 



PCT/GB 95/02858 



Patent document 
cited in search report 



Publication 
date 



Patent family 
member(s) 



Publication 
date 



EP-A-0404249 



CN-A,B 



1048945 



30 



01 



91 



DE-D- 


69014435 


12' 


-01 


-95 


DF-T- 


69014435 


01 


-06 


-95 


DF-D- 


69014436 


12 


-01 


-95 




69014436 


14 


-06 


-95 


EP-A- 


0404251 


27 


-12 


-90 


HU-B- 


208877 


28 


-01 


-94 


HU-B- 


210013 


30 


-01 


-95 


JP-A- 


3102679 


30 


-04 


-91 


JP-A- 


3034127 


14 


-02 


-91 


PL-B- 


165214 


30 


-11 


-94 


SU-A- 


1796076 


15 


-02 


-93 


US-A- 


5226027 


06 


-07 


-93 


US-A- 


5303217 


12 


-04 


-94 



W0-A-9522142 



17-08-95 



NONE 



Form PCT ISA. 210 (pMam fwn»ly annex) (July IW) 



page 2 of 2