BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a recoding format of information recording medium according to the present invention.
FIG. 2 shows an example of the recording format and allocation of memory blocks according to the present invention.
FIG. 3 shows a recoding format of information recording medium according to the present invention.
FIG. 4 shows an example of the recording format and allocation of memory blocks according to the present invention.
FIG. 5 shows a recoding format of information recording medium according to the present invention.
FIG. 6 shows an example the recording format and of allocation of memory blocks according to the present invention.
FIG. 7A shows a part in a file allocation table of the FAT file system according to a conventional technology.
FIG. 7B shows a part in a file allocation table of the FAT file system according to the present invention.
FIG. 8 is a conceptual view of a recording method for a memory card according to the conventional technology.
FIG. 9 is a conceptual view of group division in the memory card according to the conventional technology.
FIG. 10 shows a recoding format of information recording medium according to the conventional technology.
FIG. 11 shows an example of the recording format and allocation of memory blocks according to the conventional technology.
DESCRIPTION OF REFERENCE SYMBOLS
100 partition management information region
110 switch region
120 partition boot information region
130 file management information region
140 user data region
400-447 memory block
PREFERRED EMBODIMENTS OF THE PRESENT INVENTION
Preferred Embodiment 1
FIG. 1 shows a recording medium of non-volatile semiconductor, a recording format of the medium, and a recording method for the medium according to a preferred embodiment 1 of the present invention. Referring to reference numerals shown in FIG. 1, 100 denotes a partition management information region, 110 denotes a switch region, 120 denotes a partition boot information region, 130 denotes a file management information region, and 140 denotes a user data region. The partition management information region 100, which is also called master boot record, includes information such as a start position, size and type of a partition present in the recording medium, a code for reading an activation code from the partition, and the like. The partition boot information region 120, which is also called partition boot record, includes various information in the partition and the activation code. The file management information region 130 includes a file management information dependent on a file system. For example, if the file system is the FAT file system, a file allocation table is stored in the region. In the user data region 140, file entity and directory information are recorded.
A region from a starting end of the partition boot information region 120 through a terminal end of the user data region 140 corresponds to a first partition of the recording medium. A plurality of partitions can be provided in one recording medium, in that case subsequent partitions follow the first partition. The description is given below based on an example where one partition is provided in order to simplify the explanation.
For comparison, a conventional recording format is described. FIG. 10 shows a recording format of a recording medium of non-volatile semiconductor according to the conventional technology. Referring to reference numerals shown in FIG. 10, 500 denotes a partition management information region, 520 denotes a partition boot information region, 530 denotes a file management information region, and 540 denotes a user data region. These regions correspond to the regions described referring to FIG. 1, and a region from a starting end of the partition boot information region 520 through a terminal end of the user data region 540 corresponds to a first partition. However, the switch region is not secured between a terminal end of the partition management information region 500 and a starting end of the first partition in the conventional recording format shown in FIG. 10, which is a difference between the conventional technology and the preferred embodiment 1 of the present invention.
An influence generated from the absence of the secured switch region is described referring to FIG. 11. FIG. .11 shows an example of the conventional recording format and allocation of the memory blocks. Referring to reference numerals shown in FIG. 11, 500 denotes a partition management information region, 520 denotes a partition boot information region, 530 denotes a file management information region, and 540 denotes a user data region, and these regions is the same as the regions described referring to FIG. 10. Reference numerals 600, 620, 630, 640-643 and 644-64A shown in FIG. 11 each denotes a memory block, and these memory blocks are called erasing blocks or erasable blocks, in which the data is physically erased per block. In the description below, the various information regions are allocated to one memory block, however, are actually allocated to a plurality of memory blocks depending on sizes of the information regions.
The memory blocks are divided into groups. The memory blocks 600, 620, 630 and 640-643 belong to a group 1, and the memory blocks 644-64A belong to a group 2. Though not shown, a predetermined number of preliminary memory blocks (preliminary blocks) are present in each group.
When the data in the memory block is updated, the switch treatment is performed between the preliminary block or the memory block not retaining the data in the same group as described in the DESCRIPTION OF THE RELATED ART.
The partition management information region 500 is allocated to the memory block 600, the partition boot information region 520 is allocated to the memory block 620, the file management information region 530 is allocated to the memory block 630, and the user data region 540 is allocated to the memory blocks 640-64A.
With respect to the constitution of FIG. 11 thus set above, its operation is described below. Assuming that an image file is recorded in the user data region 540, the file management information region 530 is periodically updated into a latest state during the recording operation to be ready for occurrence of power shutdown. Accordingly, the data in the file management information region 530 is often updated.
In FIG. 11, the file management information region 530 is allocated to the memory block 630 at this stage. When the data is updated, the switch treatment is performed between the memory block 630 and the preliminary block or the memory block not retaining the data in the group 1 to which the memory block 630 belongs. However, in the group 1, the memory block 600 retains the data of the partition management information region 500 and the memory block 620 retains the data of the partition boot information region 520. Further, the memory blocks 640-643 retain the directory information and data of the image file. Therefore, all of the memory blocks except for the preliminary block retain the data in the group 1, and therefore, cannot be used for the switch treatment. Here, If it is presumed that each group has one preliminary block, the switch treatment is performed between the relevant memory block and the one preliminary block. As a result, the data is alternately rewritten in the two memory blocks alone, which are the memory block 630 and the preliminary block, when the data of the file management information region 530 is often updated. Thereby, the number of the rewriting operations increases in these two memory blocks and consequently the rewriting lives of these memory blocks is attained sooner than the other memory blocks.
In contrast, in the constitution according to the preferred embodiment 1, the switch region 110 is provided between the terminal end of the partition management information region 100 and the starting end of the first partition. The switch region 100, which is outside the range of the first partition, cannot be accessed by the file system that manages inside the partition. Therefore, the data in the switch region 110 is physically erased when the recording medium is initialized or the like, so that the data is not recorded in the switch region 110. As a result, the memory block in the switch region 110 can maintain the state where no data is retained therein.
An operation of the recording format in which the switch region 110 is provided according to the present invention is described referring to FIG. 2. FIG. 2 shows an example of the recording format and allocation of the memory blocks according to the present invention. Referring to reference numerals shown in FIG. 2, 100 denotes a partition management information region, 110 denotes a switch region, 120 denotes a partition boot information region, 130 denotes a file management information region, and 140 denotes a user data region. These regions are identical with those described referring to FIG. 1. In FIG. 2, each of reference numerals 400, 410-412, 420, 430, 440 and 441-447 denotes a memory block. The memory blocks are divided into groups. The memory blocks 400, 410-412, 420, 430 and 440 belong to a group 1, and the memory blocks 441-447 belong to a group 2. Though not shown, a predetermined number of preliminary memory blocks (preliminary blocks) are present in each group. The partition management information region 100 is allocated to the memory block 400, the switch region 110 is allocated to the memory blocks 410-412, the partition boot information region 120 is allocated to the memory block 420, the file management information region 130 is allocated to the memory block 430, and the user data region 140 is allocated to the memory blocks 440-447.
With respect to the constitution of FIG. 2 thus set as above, its operation is described below. Assuming that an image file is recorded in the user data region 140, the file management information region 130 is periodically updated into a latest state during the recording operation to be ready for power shutdown. Accordingly, the data in the file management information region 130 is often updated.
In FIG. 2, the file management information region 130 is allocated to the memory block 430 at this stage. When the data is updated, the switch treatment is performed between the memory block 430 and the preliminary block or the memory block not retaining the data in the group 1 to which the memory block 430 belongs. In the group 1, the memory block 400 retains the data of the partition management information region, and the memory block 420 retains the data of the partition boot information region. Further, the memory block 440 retains the directory information and data of the image file. However the memory blocks 410-412 serve as the switch region retaining no data, and can be used for the switch treatment. Presumed that each group has one preliminary block, the preliminary block can also be used for the switch treatment. As a result, the switch treatment of the data is performed between the five memory blocks in total, which are the memory blocks 430 and 410-412 and the preliminary block, when the data of the file management information region 130 is often updated.
In the conventional example in FIG. 11 described earlier, the data of the file management information region is updated using only the two memory blocks of the memory block 630 and the preliminary block. In contrast to that, in FIG. 2 according to the present invention, the five memory blocks can be used alternately for the data-update. Provided that the data of the file management information region is updated 3,600 times in the image recording for an hour, in the conventional technology where the two memory blocks are used, the rewriting number of times per one memory block becomes 3,600 times/two memory blocks=1,800 times, while it becomes 3,600/five memory blocks =720 times in the present invention. In the present invention, the rewriting number of times per one memory block can be reduced in comparison to the conventional example.
FIG. 2 shows the example in which the number of the memory blocks in one group is seven, the number of the preliminary block in one group is one, and the three memory blocks are secured as the switch region in order to simplify the description. However, the actual number of the memory blocks in one group in the semiconductor memory card is a few hundreds through a few thousands. Therefore, a larger number of memory blocks can be secured as the switch region, which largely reduces the rewriting number of times per one memory block. Thus, the switch region is secured in the same group to which the memory block including the data to be often updated belongs so that the rewriting number of times per one memory block can be reduced in comparison to the conventional example. As a result, the rewriting life of the recording medium can be increased.
The switch region is provided outside the partition in the preferred embodiment 1. More specifically, the start position of the first partition is lowered in comparison to the conventional technology so that a blank region is provided between the partition management information region (master boot record) and the start position of the first partition. Then, the data in the blank region is physically erased so that the blank region can be allocated as the switch region. The information such as where the first partition starts can be recorded in the partition management information region. In the preferred embodiment 1, the switch region can be secured irrespective of the type of the file system that manages the partition because the switch region is outside the range of the partition. Therefore, the switch region can be secured irrespective of the type of the file system even in the case where recording medium is managed under the FAT file system, UDF (Universal Disc Format) file system or any other file system.
In the case of providing at least two partitions in the recording medium in addition to the method described in the preferred embodiment 1, a start position of the second partition is lowered in place of starting the second partition immediately after an ending position of the first partition so that the switch region can be secured between the ending position of the first partition an the start position of the second partition in a similar manner. As a result, the rewriting life of the recording medium can be increased with respect to the second partition in a similar manner.
Preferred Embodiment 2
Next, a recording medium of non-volatile semiconductor in which the switch region is secured in the partition, a recording format of the medium and a recording method for the medium are described. The format inside the partition depends on the type of the file system. A preferred embodiment 2 of the present invention is described below referring to the FAT file system.
FIG. 3 shows a recording medium of non-volatile semiconductor, a recording format of the medium and a recording method for the medium according to the preferred embodiment 2. Referring to reference numerals shown in FIG. 3, 700 denotes a partition management information region, 720 denotes a partition boot information region, 710 denotes a switch region, 730 denotes a file management information region, and 740 denotes a user data region. These regions are identical with those described referring to FIG. 1.
Next, how the respective regions are allocated to the memory blocks is described referring to an allocation example shown in FIG. 4. FIG. 4 shows the example of the recording format and the allocation of the memory blocks according to the present invention. Referring to reference numerals shown in FIG. 4, 700 denotes a partition management information region, 720 denotes a partition boot information region, 710 denotes a switch region, 730 denotes a file management information region, and 740 denotes a user data region. These regions equal to those shown in FIG. 3. Each of the reference numerals 800, 820, 810-812, 830, 840 and 841-847 shown in FIG. 4 denotes a memory block. The memory blocks are divided into groups. The memory blocks 800, 820, 810-812, 830 and 840 belong to a group 1, and the memory blocks 841-847 belong to a group 2. Though not shown, a predetermined number of preliminary memory blocks (preliminary blocks) are present in each group. The partition management information region 700 is allocated to the memory block 800, the partition boot information region 720 is allocated to the memory block 820, the switch region 710 is allocated to the memory blocks 810-812, the file management information region 730 is allocated to the memory block 830, and the user data region 740 is allocated to the memory blocks 840-847.
Details of the constitution of FIG. 4 thus set above are further described. In the FAT file system, number of reserved sectors can be set in the partition boot information region 720. The number of the reserved sectors is a numeral value showing how many sectors are secured in a region prior to the start position of the file allocation table (file management information region 730 shown in FIG. 4). “1” was conventionally often set as the numeral value because only the partition boot information region 720 is present in a position prior to the file allocation table and the number of the sectors is generally “1”. In the present invention, a predetermined numeral value is set as the number of the reserved sectors so that the start position of the file allocation table is lowered, and a region generated by lowering the start position of the file allocation table is allocated to the switch region 710.
In the FAT file system, 16 bits are allocated to the set value of the number of the reserved sectors. Therefore, the 16th power of 2−1=65,535 sectors at maximum can be secured as the reserved sectors. Provided that one sector of the recording medium has 512 bytes, a securable size is 65,535 sectors×512 bytes=33,553,920=approximately 32 MB (mega bytes) at maximum. The information present in the region prior to the file allocation table is the partition boot information region 720. Further, there is other information depending on the type of the FAT file system, which is accessed by the file system. However, these other information approximately has only a few sectors, and most of the regions secured by the number of the reserved sectors are blank regions inaccessible by the FAT file system. Therefore, when the data in the memory blocks allocated to the blank regions is physically erased, the memory blocks can be made to maintain the state where no data is retained therein because no data is written therein by the file system.
In FIG. 4, the memory blocks 810-812 are allocated to the secured switch region 710. In this state, when the data update is often implemented to the file management information region 730, the switch treatment is performed between the memory block 830 and the preliminary block or the memory block not retaining any data in the group 1 to which the memory block 830 belongs. In the group 1, the memory block 800 retains the data of the partition management information region 700, and the memory block 820 retains the data of the partition boot information region 720. Further, the memory block 840 retains the directory information, data of the image file and the like. However, the memory blocks 810-812, which serve as the switch region, do not retain any data and can be used for the switch treatment. Presumed that each group has one preliminary block, the preliminary block can also be used for the switch treatment. As a result, the switch treatment is performed between the five memory blocks in total, which are the memory block 830, memory blocks 810-812 and one preliminary block, when the data of the file management information region 730 is often updated. The foregoing status is the same as described in the preferred embodiment 1 referring to FIG. 2, wherein the five memory blocks are used for the switch treatment, which reduces the rewriting number of times in one memory block. As a result, the rewriting life of the recording medium can be improved in the recording format according to the preferred embodiment 2.
In a constitution wherein the partition is not prepared in the recording medium, it is unnecessary to provide the partition management information region 700 shown in FIGS. 3 and 4. In the preferred embodiment 2, the number of the reserved sectors is set in the partition boot information region 720 so that the switch region 720 is secured. Accordingly, the format capable of securing the switch region 710 can be set in the preferred embodiment 2 irrespective of with or without the partition management information region 700. Therefore, the preferred embodiment 2 can achieve an effect similar to that of the preferred embodiment 1 even in the absence of the partition management information region 700.
In the preferred embodiment 2, the description was given with respect to the FAT file system as example, however, the preferred embodiment 2 can be applied to the UDF file system. In the UDF file system, a space bitmap showing a use condition of each sector in the recording medium is present in the file management information region 730 shown in FIG. 3. It is thought that the space bitmap is often updated in order to deal with the power shutdown during the image recording. A start position of the space bitmap on the recording medium can be arbitrarily set. In the UDF, a region called a main volume descriptor sequence is present in a part of the partition boot information region 720 shown in FIG. 3, and there is a partition descriptor in the region. The start position of the space bitmap can be described in the partition descriptor. Therefore, if the start position is described therein so that the space bitmap can start at a position lower than usual, the switch region 710 can be secured because the position of the file management information region 730 shown in FIG. 3 is lowered. As a result, a similar effect can be obtained since the number of the memory blocks usable for the switch treatment is increased.
A few other constitutions for securing an unused region were proposed for the UDF file system. An effect similar to that of the preferred embodiment described earlier can be obtained if these constitutions are utilized to secure the unused region and the data in the memory blocks in the region is physically erased.
There are various file systems other than the FAT file system and the UDF file system described above. However, the region that is not used for the recording is secured in the respective file systems in different manners, it is neglected to explain all of them here. If the region which is not used for the recording is secured based on rules of the relevant formats and the data in the region is physically erased in the other file systems as described referring to the FAT file system and UDF file system, an effect similar to that of the present invention can also be obtained.
Preferred Embodiment 3
Next, a recording medium of non-volatile semiconductor in which the switch region is secured in the user data region in the partition, a recording format of the medium and a recording method for the medium are described. The format inside the partition depends on type of the file system. A preferred embodiment 2 of the present invention is described below referring to the FAT file system.
FIG. 5 shows a recording medium of non-volatile semiconductor, a recording format of the medium and a recording method for the medium according to the present invention. Referring to reference numerals shown in FIG. 5, 900 denotes a partition management information region, 920 denotes a partition boot information region, 930 denotes a file management information region, and 940 denotes a user data region, and 910 denotes a switch region. These regions is identical with those described referring to FIG. 1. In FIG. 5, the switch region 910 is secured inside the user data region 940.
Next, how the respective regions are allocated to the memory blocks is described referring to an allocation example shown in FIG. 6. FIG. 6 shows the example of the recording format and the allocation of the memory blocks according to the present invention. Referring to reference numerals shown in FIG. 6, 900 denotes a partition management information region, 920 denotes a partition boot information region, 930 denotes a file management information region, and 940 denotes a user data region, and 910 denotes a switch region. These regions equal to those described referring to FIG. 5. Further, in FIG. 6, each of reference numerals A00, A20, A30, A40, A10-A12 and A41-A47 denotes a memory block. The memory blocks are divided into groups. The memory blocks A00, A20, A30, A40, A10-A12 belong to a group 1, and the memory blocks A41-A47 belong to a group 2. Though not shown, a predetermined number of preliminary memory blocks (preliminary blocks) are present in each group. The partition management information region 900 is allocated to the memory block A00, the partition boot information region 920 is allocated to the memory block A20, the file management information region 930 is allocated to the memory block A30, the user data region 940 is allocated to the memory blocks A40, A10-A12 and A41-A47, and the switch region 910 is allocated to the memory blocks A10-A12 in the user data region.
The constitution of FIG. 6, which is set in a state as above, is further described in detail below. In the FAT file system, the recording region is managed per cluster. The cluster is an assembly of the sectors. For example, provided that 1 cluster=32 sectors, 1 sector=512 bytes, a size of one cluster is 1 cluster=32 sectors×512 bytes=16 KB (kilobytes). When the file or the directory information is recorded in the region of 16 Kbytes, the relevant cluster has already been allocated. The file allocation table is set in the file management information region 930. In the table, information for managing a use condition of the user data region 940 per cluster is recorded.
The file allocation table of the file management information region 930 are described in detail referring to FIGS. 7A and 7B. FIGS. 7A and 7B shows a part of the file allocation table of the FAT file system. FIG. 7A shows an example of the file allocation table initialized according to the conventional format. An entry in the file allocation table denotes a use condition of one cluster. If the entry shows “0000”, the cluster corresponding to the entry is in a blank state, and “FFFF” means that the relevant cluster is used, and the terminal end of the file or directory is present in the cluster. In the absence of the terminal end in the cluster, an entry number of the cluster in which the subsequent data is present is set. In FIG. 7A, an entry 0002 is “FFFF”, and it is learnt that the relevant cluster is used by the file or directory. Because a root directory is present in the FAT file system without exception, the entry 0002 is often under a use condition by the root directory even after the recording medium is initialized. Further, in terms of restrictions of the FAT file system, entries 0000 and 0001 are in a reserved state or the like. Except for the foregoing entries 0000-0002, all of entries in the file allocation table initialized according to the conventional format are in the blank state 0000.
FIG. 7B shows an example of the file allocation table initialized according to the recording format of the present invention. A difference between FIGS. 7A and 7B is that states of the entries 0003-0005 are made to be “FFF7”. “FFF7” denotes that the cluster corresponding to the entry is a defective cluster, that is the cluster wherein the data cannot be normally written or read due to a failure of the recording medium, or the like. In the format according to the present invention, a predetermined number of clusters are previously registered in the file allocation table as the defective clusters at the time of the initialization, even though they are not actually the defective clusters. The defective cluster is not used when the file or directory is recorded in the FAT file system, and no data is written in the clusters corresponding to the entries 0003-0005. Therefore, when the data in these clusters is physically erased at initialization, the memory blocks corresponding to these clusters can be allocated as the switch region because they are in a state without including any data.
The switch region secured by the manner described above is the switch region 910 shown in FIG. 6. In FIG. 6, when the data update is often implemented to the file management information region 930, the switch treatment is performed between the memory block A30 and the preliminary block or the memory block not retaining any data in the group 1 to which the memory block A30 belongs. In the group 1, the memory block A00 retains the data of the partition management information region, and the memory block A20 retains the data of the partition boot information region. Further, the memory block A40 retains the directory information and the like. However, the memory blocks A10-A12 can be used for the switch treatment because they are the switch region and do not retain any data. If each group has one preliminary block, the preliminary block can also be used for the switch treatment. As a result, the five memory blocks in total, which are the memory block A30, memory blocks A10-A12 and one preliminary block, can be used for the switch treatment when the data of the file management information region 930 is often updated. The foregoing status is the same as described in the preferred embodiment 1 referring to FIG. 2, wherein the five memory blocks are used for the switch treatment. Thereby, the rewriting number of times per one memory block can be reduced. As a result, the rewriting life of the recording medium can be effectively improved even in the recording format according to the preferred embodiment 3.
In the format according to the present invention shown in FIG. 7B, the three clusters in total of the entries 0003-0005 are the defective clusters in order to simplify the description, however, a larger number of clusters may be actually used as the defective clusters.
The effect by the switch treatment can be obtained in the region made to be the defective clusters if the memory blocks belong to the same group as the file allocation table.
When “FFF0”-“FFF6” indicating the reserved state or “FFF8”-“FFFF” indicating the already-used state are used in place of “FFF7” indicating the defective cluster, a similar effect can be obtained because the data is not written in the relevant cluster. With respect to the bit expression of the entry of the file allocation table, 16 bits such as “FFF7” may be expressed by 12 bits of “FF7” or 32 bits of “FFFFFFF7” depending on the type of the FAT file system, wherein the present invention can be similarly applied.
The information such as the file size is recorded in the user data region as the directory information in the FAT file system. In the case of updating at frequent intervals not only the file allocation table but also the directory information such as the file size during the image recording, the switch region is secured by the format of the present invention in the same group as that of the memory block to which the frequently-updated directory information is allocated. As a result, a similar effect can be obtained.
When the directory in which the file size is frequently updated is prepared, the memory blocks may be allocated so as to belong to the group where the switch region is previously secured. For example, in FIG. 2, if the directory information is prepared in the region corresponding to the memory block 440, a similar effect can be obtained even though the directory information is frequently updated because the switch region 110 is secured in the same group.
There are many cases that the number of the preliminary block in the semiconductor recording medium is prepared at a previously determined number of pieces and it cannot be flexibly increased or decreased depending on the usage of the recording medium. However, the switch region is secured in the format of the recording medium according to the present invention, which allows the region size of the preliminary blocks to be changed. More specifically, it can be used depending on the applications because the number of the blocks used for the switch treatment can be changed depending on the format. For example, the format is made to secure a large switch region in the application of frequently updating the data so that the rewriting life can be improved. On the contrary, the format is made to secure a small switch region in the application of updating the data at low-frequency so that a large capacity used for the recording operation can be secured.
The recording formats described in the preferred embodiments 1-3 can be simultaneously used. It is known that performance on a recording rate is improved in such a manner that boundary of the partition and the boundaries of management information and user data region or the like in the file system, are brought together to a boundary of the memory blocks when the semiconductor memory card is used. Therefore, it is also effective to perform fine adjustments to the start position of each information region by combining the preferred embodiments 1-3 in order to bring together the various information regions to the boundaries of the memory blocks in addition to secure the necessary switch region.
INDUSTRIAL APPLICABILITY
As mentioned above, an information recording format and an information recording medium according to the present invention can be used for recording information in a recording medium such as a semiconductor memory card, and particularly suitably use in the case where data is often rewritten in a specific region of the recording medium.
Patent Application
20080046675
