Method and apparatus for producing an optical disk having a read-only area and a rewritable area

A method produces and an apparatus includes an optical disk, with a center, having a rewritable area and a read-only area located further out from the center than the rewritable area. The method includes the steps of and the apparatus includes units for registering first management information concerning a dummy file in a file address management area located further in toward the center than the rewritable area, the dummy file having a capacity corresponding to that of the rewritable area; registering second management information concerning files to be written into the read-only area in the file address management area so that the second management information is subsequent to the first management information and registering the files into the read-only area; and erasing the first management information from the file address management area.

BACKGROUND OF THE INVENTION 
1. Background of the Invention 
The present invention relates to a method for producing an optical disk, 
and more particularly to a method for producing an optical disk having a 
read-only area and a rewritable area. 
2. Description of the Prior Art 
An optical disk having a read-only area and a rewritable area is known. 
Such an optical disk is defined in, for example, the ISO standard. 
According to the ISO standard, a rewritable area is formed in an inner 
area of the optical disk, and a read-only area is formed in an outer area 
thereof. The rewritable area has a magneto-optic recording medium on which 
tracks are formed. The read-only area has pits formed on a recording 
medium. 
Japanese Laid-Open Patent Application No. 2-101925 discloses an optical 
disk which has a file address management area formed in an innermost area 
of the optical disk. The file address management area includes information 
indicating directory tracks. A read-only area is formed further out than 
the file address management area, and a rewritable area is formed further 
out than the read-only area. The above optical disk is called a 
partially-read-only optical disk. A similar optical disk is also disclosed 
in Japanese Laid-Open Patent Application No. 4-1979. 
Information is recorded on and read from the optical disk while the optical 
disk is being rotated at a constant angular velocity. In this case, the 
linear speed measured at an outer portion of the optical disk is greater 
than that measured at an inner portion thereof. Hence, a laser beam for 
recording information on the rewritable area needs a large amount of power 
because the rewritable area is rotated at a high velocity. Normally, the 
power of the laser beam used for recording is greater than that for 
reading. A tracking servo control of the rewritable area is carried out 
using grooves arranged in the circular direction of the optical disk. The 
linear velocity of the rewritable area formed in the outer area of the 
optical disk is great; hence, the response of the tracking servo control 
is low. This may cause tracking errors. 
An optical disk in which the read-only area is further out than the 
rewritable area does not have the above-mentioned problems. In this case, 
the file address management area is formed further in than the rewritable 
area. According to general disk management operating systems, files are 
sequentially recorded on the optical disk from the inner area to the outer 
area. In other words, files are recorded on the optical disk from an idle 
recording area located further in than other idle recording areas. When 
information is written into the read-only area during the production 
process, it is necessary for the rewritable area to be filled with files. 
In the rewritable area, the addresses of files written into the rewritable 
area are registered from the innermost inner portion of the file address 
management area, and the addresses of files written into the rewritable 
area are registered so as to be subsequent to the addresses of files in 
the read-only area. If the rewritable area has unused portions, the 
address information concerning the read-only area cannot be registered in 
the file address management area. 
SUMMARY OF THE INVENTION 
It is a general object of the present invention to provide a method and 
apparatus for producing an optical disk in which the above disadvantage is 
eliminated. 
A more specific object of the present invention is to provide a method and 
apparatus for producing an optical disk having an idle rewritable area and 
a read-only area in which files have been written. 
The above objects of the present invention are achieved by a method for 
producing an optical disk having a rewritable area and a read-only area 
located further out than the rewritable area, the method comprising the 
steps of: (a) registering first management information concerning a dummy 
file in a file address management area located further in than the 
rewritable area, the dummy file having a capacity corresponding to that of 
the rewritable area; (b) registering second management information 
concerning files to be written into the read-only area in the file address 
management area so that the second management information is subsequent to 
the first management information and registering the files into the 
read-only area; and (c) erasing the first management information from the 
file address management area. 
The above objects of the present invention are also achieved by an 
apparatus for producing an optical disk having a rewritable area and a 
read-only area located further out than the rewritable area, the apparatus 
comprising: first means for registering first management information 
concerning a dummy file in a file address management area located further 
in than the rewritable area, the dummy file having a capacity 
corresponding to that of the rewritable area; second means for registering 
second management information concerning files to be written into the 
read-only area in the file address management area so that the second 
management information is subsequent to the first management information 
and for registering the files into the read-only area; and third means for 
erasing the first management information from the file address management 
area.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1A is a plan view of a partially-read-only optical disk having a 
read-only area located further out than a rewritable area, and FIG. 1B is 
a perspective view of a part of the partially-read-only optical disk shown 
in FIG. 1A. The partially-read-only optical disk 12 shown in FIGS. 1A and 
1B has a rewritable area 10 formed in an inner portion of the disk and a 
read-only area 11 formed in an outer portion thereof. As shown in FIG. 1B, 
the optical disk 12 has a base 13 on which a magnetizable film 14 is 
coated. Grooves 15 are formed in the circular direction on a surface 
portion of the magnetized film 14 within the rewritable area 10. Pits 16 
are formed in the circular direction on a surface portion of the 
magnetized film 14 within the read-only area 11. 
A disk format of the optical disk 12 is shown in FIG. 2A. A file address 
management area 18 is formed in an innermost area of the optical disk 12. 
The rewritable area 10 is formed further out than the file address 
management area 18, and the read-only area 11 is further out than the 
rewritable area 10. The management area 18 and the rewritable area 10 are 
rewritable areas. 
When the above-mentioned partially-read-only optical disk is used, 
information is read therefrom in such a manner that the rewritable area 10 
and the read-only area 11, physically separated from each other, are 
located in a logically identical section. In this manner, information can 
be read from the optical disk without recognizing whether the information 
is from the rewritable area 10 or the read-only area 11. It will be noted 
that information can be written into only the rewritable area 10. The file 
address management area 18 integrally manages the addresses of files 
written into the rewritable area 10 and the read-only area 11. 
FIG. 2B shows a disk format of a general disk management operating system, 
which includes a disk starting sector area 20, a file allocation table 
(FAT) area 21, a root directory entry area 22, and a user's area 23, in 
this order, from the innermost side of the optical disk 12. The disk 
starting sector area 20 stores information necessary to start the 
operation system recorded on the optical disk 12. The FAT area 21 stores 
information concerning a cluster chain. The cluster chain means a chain of 
clusters. The cluster is a minimum recordable unit on the optical disk 12. 
Normally, one cluster consists of a few sectors formed on the optical disk 
12. The cluster chain information indicates a cluster number and a 
subsequent cluster number. By tracing the cluster chain information, it is 
possible to identify the positions of files recorded on the optical disk 
12. The root directory entry area 22 stores information indicating the 
file names of user's files and the starting cluster numbers of these 
files. The above areas 20, 21 and 22 correspond to the file address 
management area 18, and the user's area 23 corresponds to the rewritable 
area 10 and the read-only area 11. 
When a file is read from the optical disk 12, the file name of that file 
and the starting cluster number thereof are read from the root directory 
entry area 22, and subsequently the cluster chain information recorded in 
the FAT area 21 is traced. In this manner, the position of the file to be 
read is identified, and the user's area 23 is accessed. 
When a file is recorded on the optical disk 12, an unused cluster number, 
which is the minimum cluster, number among the unused clusters is read 
from the FAT area 21, and data of the file is sequentially stored in the 
clusters in the increasing order of the cluster number from the minimum 
cluster number in order to efficiently use unused portions in the user's 
area. In this manner, data is sequentially recorded on the optical disk 12 
from the inner side of the optical disk 12 without any unused area located 
further in than the current recording position. 
Hence, it is necessary for the rewritable area 10 to be full of data when 
data is written into the read-only area during the production process. 
Conventionally, there is no efficient way to write data into the read-only 
area, and optical disks as shown in FIGS. 1A and 1B cannot be produced. 
The present invention is intended to provide an efficient method and 
apparatus for producing an optical disk having a read-only area having 
recorded files and a rewritable area which is virgin and located further 
in than the read-only area. 
FIG. 3 is a diagram of the principle of the present invention. In FIG. 3, 
parts that are the same as those shown in the previously described figures 
are given the same reference numbers previously used. An optical disk 
producing apparatus shown in FIG. 3 includes a dummy file management 
information registration unit M1, a read-only-area registration unit M2, 
and an erasing unit M3. The dummy file management information registration 
unit M1 registers, in the file address management area 18 located further 
in than the user's area 23, management information concerning a dummy file 
written into the rewritable area 10. The read-only area registration unit 
M2 registers management information concerning files written into the 
read-only area 11 so as to be subsequent to the management information 
concerning the dummy file. Further, the read-only area registration unit 
M2 registers files in the read-only area 11. The erasing unit M3 erases 
the management information concerning the dummy file written into the 
rewritable area 10 from the file address management area 18. 
According to the present invention, management information concerning a 
dummy file written into the rewritable area 10 is registered in the file 
address management area 18. Then, management information concerning the 
read-only area is written into the file address management area 18 so as 
to be subsequent to the management information concerning a dummy file, 
and files are written into the read-only area 11. Thereafter, the 
management information concerning the dumpy file written into the 
rewritable area 11 is erased from the file address management area 18. 
Hence, it becomes possible to produce an optical disk having a virgin 
rewritable area, and a read-only area in which files have been written. 
FIG. 4 is a block diagram of a part of an optical disk producing apparatus 
according to an embodiment of the present invention. The structure shown 
in FIG. 4 functions as a file address information generating device. An 
information input unit 30, such as a keyboard, is used to input a capacity 
of the read-only area 11 of optical disks to be produced and/or a capacity 
of the rewritable area 10 thereof. The input information is sent to a CPU 
33 via an information input controller 31 and a bus 32, to which a memory 
34, a display controller 35 and an external storage unit controller 39 are 
connected. The memory 34 is used to store programs executed by the CPU 33, 
and functions as a working memory of the CPU 33. The display controller 35 
controls a display on a CRT 36. The controller 39 performs input/output 
control of external storage units 37 and 38, such as optical disk units. 
Files to be registered in the read-only area 11 are previously stored in 
the external storage unit 37 located on the file input side. Hereinafter, 
such files are referred to as ROM files. Original data is written onto a 
reference optical disk accommodated in the external storage unit 38 on the 
file output side. 
FIG. 5 is a flowchart of a process for generating the original data by 
means of the structure shown in FIG. 4. The original data is written onto 
the reference optical disk in the external storage unit 37. In step S2, 
information indicating the capacity of the read-only area 11 and/or the 
capacity of the rewritable area 10 is input by means of the information 
input unit 30. In step S4, the CPU 33 calculates the ending address of the 
rewritable area 10 and the starting address of the read-only area 11. 
Further, in step S4, the CPU 33 calculates the number of clusters related 
to the dummy file (dummy clusters), the above number of clusters 
corresponding to the capacity of the rewritable area 10. A layout of the 
optical disk obtained by the above calculation is displayed on the CRT 36. 
In step S6, the CPU 33 writes the number of dummy clusters calculated by 
step S4 onto the reference optical disk in the external storage device 38, 
starting from the starting (innermost side) position of the FAT area 21. 
Now, the following will be assumed: 1) the cluster number ranges from 
OO.sub.H to FF.sub.H (H denotes the hexadecimal notation), 2) cluster 
number 00.sub.H denotes that the cluster is vacant, 3) cluster numbers 
02.sub.H -FF.sub.H form a cluster chain, and 4) cluster number 01.sub.H 
denotes a dummy cluster. As shown in FIG. 6A, cluster number 01.sub.H is 
written into a dummy cluster area 21a in the FAT area 21 that has been 
initialized by means of cluster number 00.sub.H, and it is considered that 
a dummy file has been written into the rewritable area 10 of the user's 
area 23. 
In step S8, the CPU 33 sequentially reads ROM files to be written into the 
read-only area 11 from the external storage unit 37, and copies the read 
ROM files onto the reference optical disk in the external storage unit 38. 
Hence, entry information concerning the ROM files written into the 
read-only area 11 is written into the root directory entry area 22. 
Further, as shown in FIG. 6B, a cluster chain area 21b of the ROM files 
written into the read-only area 11 is formed in the FAT area 21 so as to 
be subsequent to the dummy cluster area 21a, and the ROM files are written 
into the read-only area 11 so as to be subsequent to the dummy file 
written into the rewritable area 10 of the user's area 23. 
In step S10, the CPU 33 instructs the external storage unit 38 to erase the 
dummy cluster area 21a from the FAT area 21. Hence, as shown in FIG. 6C, 
the dummy clusters assigned cluster number 01.sub.H are changed to 
clusters assigned cluster number 00.sub.H, whereby the virgin rewritable 
area 10 can be formed in the user area 23. In step S12, information 
concerning the disk starting sector area 20, information concerning the 
ROM file cluster area 21b, and information concerning the root directory 
entry area 22 are added to the tail end of the read-only area 11. 
FIG. 7 is a block diagram of an original stamper producing apparatus. An 
information input unit 40 such as a keyboard is connected to a bus 42 via 
an information input controller 41. A CPU 43, a memory 44, a display 
controller 45, an external storage unit controller 49, error correction 
information controller 51, and an exposure apparatus controller 52 are 
connected to the bus 42. The memory 44 stores programs to be executed by 
the CPU 43 and functions as a working memory of the CPU 43. The display 
controller 45 performs a display control of a CRT 46. The external storage 
unit controller 49 controls an input/output control of an external storage 
unit 47, such as an optical disk unit. 
The reference optical disk onto which the original data has been written by 
means of the structure shown in FIG. 4 is inserted into the external 
storage unit 47. 
An ECC (Error Correction Code) generator 53 is coupled to the error 
correction information controller 51 via a controller 52 with an ECC 
function added thereto. A parity generator 55 is coupled to the error 
correction information controller 51 via a controller 54 with a parity 
function added thereto. The ECC generator 53 generates an ECC code of 80 
bytes with respect to one block (equal to 512 bytes) of ROM file data 
stored in the read-only area 11 with the management information added 
thereto and read from the external storage unit 47, and adds such an ECC 
code to the one block. The parity generator 54 generates a parity code of 
one block with respect to 25 blocks equal to one track, and adds such a 
parity code to the 25-block data. 
A servo mechanism 61 is connected to the exposure apparatus controller 68 
via a servo controller 60. A spindle motor 63 is connected to the exposure 
apparatus controller 68 via a spindle motor controller 62. An optical head 
65 is connected to the exposure apparatus controller 68 via an optical 
head controller 64. The spindle motor 63 rotates an original stamper 66 at 
a constant velocity under the control of the controller 62. The servo 
mechanism 61 positions the optical head 65 at a desired position under the 
control of the controller 60. In this state, the optical head 65 writes 
the management information added ROM files with the ECC code and the 
parity code added thereto onto predetermined tracks (on the outer side of 
the disk) in the form of pits. A plurality of partially-read-only optical 
disks can be produced using the original stamper 66. 
The formatting process is carried out at the commencement of use of the 
optical disk. The management information is read from the read-only area 
11, and is written into the disk starting sector area 20, the ROM file 
cluster area 21b and the root directory entry area 22, these areas being 
formed in the rewritable area 10. Hence, the optical disk becomes usable. 
As has been described above, according to the present invention, management 
information concerning the dummy file (dummy clusters) is registered in 
the rewritable area 10. Thereafter, management information concerning ROM 
files (ROM file clusters) written into the read-only area is registered 
and ROM files are written into the read-only area 11. Hence, it is 
possible to register the ROM files in the read-only area 11 so as to be 
subsequent to the dummy file in the rewritable area 10 and to provide the 
virgin rewritable area 10 because the management information (dummy 
clusters) concerning the dummy file written into the rewritable area 10 is 
erased. 
In the above-mentioned embodiment, only the dummy clusters are written onto 
the reference optical disk and the dummy file is not actually written into 
the rewritable area 10 of the user's area 23. However, it is also possible 
to employ a process as shown in FIGS. 8A through 8C. The dummy file is 
actually written into the rewritable area 10 as shown in FIG. 8A, and ROM 
files are written into the read-only area 11 so as to be subsequent to the 
dummy file as shown in FIG. 8B. Then, the management information 
concerning the dummy file is erased from the FAT area 21, as shown in FIG. 
8C. However, it may take a long time to actually write the dummy file in 
the rewritable area 10. 
The present invention is not limited to the specifically disclosed 
embodiments, and variations and modifications may be made without 
departing from the scope of the present invention.