Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
2000-03-17
2003-09-02
Iqbal, Nadeem (Department: 2184)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C711S134000
Reexamination Certificate
active
06615363
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to optical disks, and particularly to an optical disk having a novel format and a method of recording information on the same. That is, the present invention relates to a technology suitable for the format specifications of the next-generation rewritable optical disks such as MO, ASMO, MD-DATA, DVD-RAM and PD.
Magnetooptical disks, such as ASMO (Advanced Storage Magnetooptical Disk) each have a storage capacity of 6 GB or more, and the user can freely write information on these disks. A typical one of these disks has record management areas provided along the innermost and outermost peripheries of the disk with respect to its radius direction (across the tracks), and a plurality of bands provided between those peripheries. The record management areas are sometimes called a lead-in area and a lead-out area. The outermost and innermost peripheries are assigned to the lead-in and lead-out areas or to the lead-out and lead-in areas, respectively. This assignment is selective and depends on the specifications to be used.
The record management areas are prepared for the recording and reproducing system for the whole disk, the positional information of data area (for example, replacement area information which will be described later) and the other management information (for example, security data), and they are used only by the manufacturers, or cannot be changed by the user. The management information has so far been redundantly recorded in the two innermost and outermost record management areas in order to increase the reliability, and further recorded typically doubly even in one record management area. As a result, one management information has been quadruply recorded in the innermost and outermost record management areas. The reason was that when a disk was corroded by rust, the innermost or outermost record management area was empirically often all disabled.
The user can make access to each band which is composed typically of a data area and a replacement area. The data area is a area in which the user records certain data. The replacement area has replacement blocks stored for defective blocks (sectors) present in the data area. Therefore, if the data area includes no defective block, no data is written in the replacement area. The addresses in the replacement area are written in the above-mentioned record management areas.
The ASMO has sectors of the same length in order to record each track at a substantially constant density. Since the length of the circumference (in the sector direction) increases as we go from the inner to outer periphery of the disk, the number of sectors per circumference increases as we go from the inner to outer periphery of the disk. Each band is conceptually composed of one data area and one replacement area corresponding thereto. As the methods of arranging the sectors (physical format), there are known three kinds of systems: CLV (Constant Linear Velocity), CAV (Constant Angular Velocity) and ZCAV (Zone Constant Angular Velocity). For example, in the CAV or ZCAV system, the revolution velocity (angular velocity) is substantially constant in the inner and outer peripheries, and the synchronizing clock frequency for recording and reproduction is changed. For the ASMO, a CLV system is employed in which the rotation velocity is changed, and the clock frequency is constant.
SUMMARY OF THE INVENTION
In the conventional ASMO, if a defective block is found present in the data area and replaced by the replacement area during recording, the optical head is required to move to the innermost or outermost record management area and write this information therein. However, since three different rotation rates are assigned to the innermost and outermost peripheries and the corresponding band, large power is necessary to control a driving motor to drive for the writing. In addition, since the optical head is forced to move from the corresponding band to the innermost or outermost record management area, it takes a time to access. Thus if, for example, music or images (for example, motion pictures) to be continuously recorded were recorded on the ASMO, the information was sometimes partially not recorded due to the necessary access time at the replacement time, and the recording operation was stopped at that time. This trouble was not peculiar to the CLV system. Even if the CATV or ZCAV system were employed, the optical head had to move to the innermost or outermost recording area at the replacement time, and thus similarly it took a long time to access.
Accordingly, it is a general object of the present invention to provide a novel and useful optical disk and method of recording information on the same with the above problems solved.
Specifically, it is an object of the invention to provide an optical disk and method of recording information on the same in which the necessary time for the replacement is made shorter than in the prior art so that music and images (for example, motion pictures) can be recorded without dropout of information.
It is another object of the invention to provide an optical disk and method of recording information on the same in which the power necessary for the replacement time can be decreased as compared with that in the prior art when the CLV system is employed for a physical format.
It is still another object of the invention to provide an optical disk and method of recording information on the same in which the reliability of the replacement information can be maintained high and/or improved.
According to a first aspect of the invention, there is provided an optical disk formatted to have a record management area in which management information can be stored and of which the contents cannot be rewritten by the user, a data area to which the user can make access, and a replacement area capable of providing replacement blocks for defective blocks that exist in the data area, the record management area being provided at three or more locations on the optical disk so that different contents of the management information can be respectively stored in the management areas located at the different places.
The conventional optical disk has two record management areas respectively provided along the innermost and outermost peripheries, the two management areas having stored therein the same information. The optical disk according to the first aspect of the invention provides a novel format in place of the conventional one. That is, the optical disk according to this aspect has three or more record management areas on the disk, and these management areas are capable of storing different management information depending on the locations at which the management areas are provided. Therefore, the contents of the management information can be divided into a plurality of different information and disposed in different places in order that the management information cannot be lost and that predetermined processes can be well conducted. The management information includes one to promote that, for example, the moving time of the head can be reduced in the record processing or replacement processing and that the number of times the revolution rate of the disk or the clock frequency is changed can be decreased. In an example of the optical disk according to this aspect of the invention, although the management information of at least two areas of the three or more record management areas are different, the management information of all the three management areas may be the same. For example, in another example of this aspect, during the recording processing only the central management area is accessed and updated in its contents, and after the recording operation ends and before the power is turned off the management information in the central management area is copied into the other management areas.
According to a second aspect of the invention, there is provided an optical disk according to the first aspect of the invention, wherein the management information stored in the recor
Hitachi Maxell Ltd.
Iqbal Nadeem
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