JP3536359B2 - Control method of flash memory - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash memory recording method used as an image recording medium. 2. Description of the Related Art Conventionally, flash memories have been used as image recording media. FIG. 8 shows a schematic configuration of an electronic camera using such a flash memory. The CCD 801 converts an image signal into an electric signal, and the A / D converter 80 converts an analog signal into a digital signal.
2. A timing generator 80 for generating a timing signal for controlling a driving circuit 804 for driving the CCD 801
3. A compression / expansion circuit 805 for compressing / expanding a digital image signal by encoding / decoding, a DRAM 806 for temporarily recording a captured digital image signal, a flash memory 807 for storing a compressed video signal, and a ROM 80
Together it operates based on a program recorded in 8, CPU 811 that operates based on input from using RAM 809 as a work RAM key input unit 810,
Signal generator 812 for generating a digital video signal by adding a synchronization signal to a digital image signal, VRAM 813 for recording digital video signals, digital video signals output from the signal di <br/> Enereta 812 into an analog signal D / A converter 814 for conversion, amplifier 8
An LCD 816 for driving a liquid crystal based on an analog video signal input through the LCD 15 to display an image, a CPU 8
An interface 817 for inputting / outputting a video signal or the like converted into a serial signal at 11 is provided. In the electronic camera configured as described above, when recording on the flash memory 807 , first, the key input unit 8
When the video capture key is operated at 10 , the drive circuit 80 is driven by a timing signal from the timing generator 803.
4 and fetches video from CCD 801 and A / D
The converter 802 converts the analog signal into a digital signal and temporarily records the digital signal in the DRAM 806 as a digital image signal. Then, the recorded video signal to DRAM 806 to perform the color processing, to create a luminance signal and a chrominance signal from the video signal, the compression / decompression circuit these luminance signal and the color signal 8
05 and compresses the luminance signal and the chrominance data, and records the data in the flash memory 807 . On the other hand, when reproducing a video signal, the key input unit 8
When the play key is operated at 10 , the flash memory 807
A predetermined compressed video signal (compressed luminance signal and color signal) is read out and transferred to the compression / expansion circuit 805 . Then, the luminance signal and the chrominance signal are expanded, a synchronizing signal is added by a signal generator 812 to generate a digital video signal, and a digital video signal is generated via a D / A converter 814 and an amplifier 815.
D 816 . Some of the above-mentioned electronic cameras can switch between two types of compression modes, high compression and low compression, as a compression mode for image data. The recording modes that can be used by switching between such compression modes are different in the recording capacity between when recording in the high compression mode and when recording in the low compression mode, and image data having different recording capacities are mixed and shared. The data is recorded in the flash memory 807 . [0006] However, in the case of recording image data having different recording capacities in a mixed manner in the flash memory 807 as described above, the recording area of the image data in the high compression mode having a small recording capacity is required. Since the recording area for the image data in the low compression mode having a large recording capacity is provided respectively, even if the image data in the high compression mode having the small recording capacity is erased in any number of places, these erased recording areas are provided. Cannot record image data in the low-compression mode with a large recording capacity, but can only re-record image data in the high-compression mode with the same recording capacity, and the use efficiency of the flash memory 807 is significantly reduced. There was a problem. On the other hand, some flash memories 807 erase image data in blocks. Flash memory 80 adopting such a block erase method
Numeral 7 indicates that the recording area is composed of a plurality of blocks having a predetermined capacity. For example, if the recording capacity is 4 Mbit, 32 blocks each having 16 Kbits per block. In the flash memory 807 configured as described above, if the image data has a one-to-one relationship with one block, when erasing the image data, the contents of the corresponding block may be erased. Usually, the capacity of the image data to be recorded is irrelevant to the size of the block, and there are many cases where it is desired to erase only a predetermined portion in the block. For this reason, the conventional flash memory 8
07 , a DRAM having a recording capacity of one block is prepared, and the flash memory 8 to be erased is stored in this DRAM.
A method of saving the unerased portion in the block No. 07 , erasing the block, and then rewriting the image data saved in the DRAM into the flash memory 807 has been considered. A DRAM is required separately from 807, and image data is stored in a DRA
If the main power supply is turned off for some reason during retreat to M, there is a possibility that image data in the DRAM may be lost, and there is a problem that stable operation cannot be guaranteed. A first object of the present invention is to provide a flash memory control method capable of improving the use efficiency of the flash memory. A second object of the present invention is to provide a flash memory control method capable of guaranteeing a stable operation. According to the present invention, the same storage capacity is used.
Block with multiple volumes, at least
a first block having m clusters of n clusters, and n
The first block having m second blocks having clusters;
One cluster forming each set of blocks and the second
Image data in high compression mode is obtained by one cluster of blocks.
Data and record the first set of blocks.
Clusters to be formed and all clusters of the second block
To record image data in low compression mode
In the flash memory, the cluster of the erased image is the first
Erasing the corresponding set in any of the sets in the block
If there are no recorded clusters other than the image,
And the cluster of the erased image is
In each of the sets, the corresponding
Second block with recorded cluster and erased image
If there are recorded clusters other than the erased image,
Clusters other than the erased image of the block
Record other than the erased image of the second block in the empty cluster of
A completed cluster to an empty cluster of another second block
After each copy, erased image cluster and copied
Only clusters are deleted . As a result, according to the present invention, the class of the erased image is
Data in any of the sets of the first block
If there are no recorded clusters other than the erased image in the
Image clusters, and erased image clusters
Either of the sets in the block 1
There are recorded clusters other than the deleted image, and there is an erased image
Clusters other than the erased image in the second block
If there is, the recorded clips other than the erased image of the first block
Copy the raster to another set of empty clusters,
Clusters other than the erased image of block 2
Copy to the empty cluster of the second block,
Delete clusters and copied clusters
Therefore, erasing image data in high compression mode
The sky for one image in the low compression mode can always be secured. Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a schematic configuration of a flash memory to which the control method of the present invention is applied. in this case,
The flash memory has one P block P0 and four C blocks.
One group is composed of the blocks C0 to C3, and this one group can record image data of 12 images in a high compression mode and 4 images in a low compression mode described later. Here, the P block P0 is composed of 12 clusters as shown in FIG. 2A, codes EP0 to EP11 are allocated to these 12 clusters, and C blocks C0 to C3 are As shown in FIG. 2B, each cluster is composed of three clusters, and codes EC0 to EC2 are assigned to these three clusters. In the high compression mode having a small recording capacity as the compression mode of the image data, EP0 + EC0, E0
One image data is recorded by a combination of the cluster of the P block P0 and the cluster of the C blocks C0 to C3 as in P1 + EC1,..., While in the low compression mode with a large recording capacity as the compression mode of the image data, P
0, EP0 to EP2 are converted to cluster codes NP0, EP3 to
If EP5 is assigned to the cluster code NP1, EP6 to EP8 is assigned to the cluster code NP2, EP9 to EP11 is assigned to the cluster code NP3, and EC0 to EC2 of each of the C blocks C0 to C3 are assigned to the code NC, NP0 + NC, NP1 + NC,. By recording one image data in such a combination, the recording capacities of the high compression mode and the low compression mode are in a one-to-three relationship. Now, as shown in FIG. 3, the first image data is EP0 of P0 and EC0 of C00 in the high compression mode, and the second image data is N0 of P0 in the low compression mode.
In the high compression mode, the NC of P1 and C01 and the third and fourth image data are EP6 of P0, EC0 of C02 and E of P0.
It is assumed that EC1 of P7 and C02 and the image data of the fifth sheet are recorded in NP3 of P0 and NC of C03 in the low compression mode, respectively. When erasing an image in each compression mode from this state, the flowchart shown in FIG. 4 is executed.
First, the first high compression mode image (EP1 and C1 of P0)
When erasing (EC0) of 00, it is determined in step 401 whether the erased image is in the high compression mode. Here, since YES is determined, the process proceeds to step 402, where it is determined whether the P cluster group of the erased image is EP0 to EP2. Then, since this step 402 is also YES, step 403 is executed.
To determine whether there is a recorded P cluster other than the erased image in EP0 to EP2. In this case, since the answer is NO, the process proceeds to step 404 to erase the cluster of the erased image. Thereby, both EP0 to EP2 of P0 and C00 are vacant, and the vacancy for one image in the low compression mode is secured. Next, the second image in the low compression mode (P0
NP1 and NC of C01) are to be erased, it is determined in step 401 whether the erased image is in the high compression mode. Here, since it is NO, the process proceeds to step 404, and the cluster of the erased image is erased. Thereby, NP of P0
The NCs 1 and C01 are both empty, and the sky for one image in the low compression mode is secured again. Next, the third image in the high compression mode (P0
When erasing EP0 and EC0 of C02), it is determined in step 401 whether the erased image is in the high compression mode. Here, since YES is determined, the process proceeds to step 402, where it is determined whether the P cluster group of the erased image is EP0 to EP2. Then, here, the answer is NO, so that step 405 is executed.
Then, it is determined whether the P cluster group of the erased image is EP3 to EP5. In step 406, it is determined whether the P cluster group of the erased image is EP6 to EP8. Here, since the answer is YES, the process proceeds to step 407, and it is determined whether there is a recorded P cluster other than the erased image in EP6 to EP8. In this case, the answer is NO, and the process proceeds to step 408, where it is determined whether or not there is a recorded C cluster other than the erased image in the C block of the erased image. It is determined whether there is an empty P cluster other than the P cluster group of the image. In this case, P0
Since there is an empty space in EP0 to EP2, YES is determined, and the process proceeds to step 410, and it is determined whether there is an empty C cluster other than the C block of the erased image. Also in this case, since there is an empty space in C00, the result is YES, and the process proceeds to step 411. In step 411, the recorded P cluster is copied to an empty P cluster. Here, EP7 of P0
Is copied to EP1 of P0. Subsequently, in step 412, the recorded C cluster is copied to the empty C cluster. Here, EC1 of C02 is copied to EC1 of C00. Then, the process proceeds to step 413, where the cluster of the erased image and the copied cluster are erased. As a result, both EP6 to EP8 of P0 and C02 are vacant, and the vacancy for one image in the low compression mode is secured. The fourth image in the high compression mode (P0
The same operation as that of the third and second images described above is performed for erasing the EP7 and EC2 of C02) and the fifth low-compression mode image (NP3 of P0 and NC of C03). . Further, in erasing an image in the high compression mode,
When the P cluster group of the erased image is EP3 to EP5, the process proceeds through steps 401 and 402 to 405 and 414. When the P cluster group of the erased image is EP9 to EP11, the process proceeds to steps 401 and 402. , Steps 405 and 406 to Step 415 perform the same operations as described above. If the determinations in steps 408, 409, and 410 are NO, respectively, it means that a cluster for copying cannot be found, and in step 404, the process ends by deleting the cluster of the erased image. Therefore, according to the first embodiment,
When recording high compression mode image data and low compression mode image data using a P block having four sets of three clusters and a flash memory having four C blocks having three clusters, an erased image is recorded. If the cluster is in any one of the sets of the P blocks and there is no recorded cluster other than the erased image in the corresponding set, the cluster of the erased image is directly erased, and the cluster of the erased image is any of the sets of the P block. If there is a recorded cluster other than the erased image in the corresponding set and there is also a recorded cluster other than the erased image in the C block having the erased image, the recorded clusters other than the erased image in the P block are replaced. In the set of empty clusters, recorded clusters other than the erased image of block C
After copying each static empty cluster of another C block, so I would like to erase the cluster and copied cluster erasing images, by erasing the image data of the high compression mode, one always low compression mode image As a result, it is possible to secure the empty space for the minutes, and it is possible to increase the use efficiency of the flash memory regardless of the use condition. Then, 3 of these blocks 1 to 32
One block is a data storage block, and the remaining one block is a spare block. Since the flash memory can only be erased block by block, when erasing data, copy the unerased part of the block in which the data to be erased is recorded to a spare block, and then erase the block and erase this block. The set block is used as the next spare block. FIG. 6 explains the movement of the data storage block and the spare block. In this case, it is assumed that the blocks 1 to 32 are managed by assigning block numbers 1 to 32 respectively. Data block code storage unit 4 of 31 blocks for storing block codes (block numbers) registered as data blocks
1 and a spare block code storage unit 42 of one block for storing a block code (block number) registered as a spare block. Before the erasure is performed, FIG.
As shown in (1), the block codes of blocks 1 to 31 are stored in the data block code storage unit 41 , and the block code of the block 32 is stored in the spare block code storage unit 42 . In this embodiment, the address of block 1 is "H'00000" (H 'indicates hexadecimal), and the block size is "H'4000".
Therefore, the address of the block 2 is “H′0400
0 ", the address of block 3 is"H'08000",
... The address of the block 32 is “H′7C000”. From this state, when erasing data in the fourth block, for example, in the flowchart shown in FIG. 7, first, in step 701, "spare block code-1", that is, the spare block code is currently 32 Therefore, the variable A is 31 (= 32-1). Next, in step 702, the spare block address “H′7C0” is obtained by “H′4000 (size of one block) × A”.
00 ”(= H′4000 × 31). Similarly, in step 703, "erase block code-1", that is, the erase block code is 4, so that the variable B is 3 (= 4-1). Next, in step 704, "H'4000 (size of one block)
× B ”to erase block address“ H'0C000 ”
(= H'4000 × 3) is calculated. [0035] Then, unerased partial data reserved block address "H'7C the in erase block 4 indicated by the erase block address"H'0C000"in step 705
000 ", the spare block code 32 of the spare block code storage unit 42 and the erase block code 4 of the data block code storage unit 41 are exchanged at step 706, and the erase block 4 is blocked at step 707. to erase. As a result, FIG.
As shown in (b), the data block code storage unit 4
The fourth block code of 1 is changed to 32, the spare block code storage section 42 is changed to block code 4, and the contents of the fourth block are erased. Next, when erasing data in the tenth block, steps 701 to 701 are performed in the same manner as described above.
In step 704, a spare block address and an erase block address are set. Then, in step 705, an unerased portion in the erase block 10 is copied to the spare block 4.
In step 706, the spare block code 4 in the spare block code storage unit 42 and the data block code storage unit 41
Of the erase block code 10 in step 707
Erases the block of the erase block 10. This allows
As shown in FIG. 6C, the tenth block code in the data block code storage unit 41 is changed to 4, and the spare block code storage unit 42 is changed to the block code 10, and
The contents of the 0th block will be erased. Therefore, according to the second embodiment,
A data storage block and a spare block are provided in a flash memory composed of blocks 1 to 32, and when erasing data, an unerased portion of the data storage block in which data to be erased is recorded is copied to the spare block. Then, by erasing the block in which the erased data is to be recorded, and using the block from which the data has been erased as the next spare block, it becomes possible to erase a predetermined data size in the block. Thus, stable operation can be guaranteed without erasing the image data. As described in detail above, according to the present invention, low-compressed image data is recorded by moving recorded high-compressed image data to another area in accordance with erasure of high-compressed image data. When the available area can be secured, the recorded high-compression image data is moved to another area.Therefore, by erasing the image data in the high-compression mode, the recording area for the low-compression image data must always be secured. Can be. Further, according to the present invention, when erasing image data in the low compression mode, it is possible to always secure a space for one image in the low compression mode by reconstructing by exchanging clusters. Regardless of the situation, the use efficiency of the flash memory can be improved. Further, according to the present invention, after copying data of an unerased portion of a block to be erased to a spare block,
Since the block is erased, it becomes possible to erase a predetermined data size in the block, and the conventional DRA
Compared to the case using M, image data does not disappear and stable operation can be guaranteed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a schematic configuration of a flash memory to which a control method according to a first embodiment of the present invention is applied. FIG. 2 is a diagram showing P blocks and C blocks constituting a flash memory to which the control method of the first embodiment is applied. FIG. 3 is a diagram showing a recording state of image data in a flash memory to which the control method of the first embodiment is applied. FIG. 4 is a flowchart for explaining the operation of the first embodiment. FIG. 5 is a diagram showing a schematic configuration of a flash memory to which a control method according to a second embodiment of the present invention is applied; FIG. 6 is a diagram for explaining the movement of a data storage block and a spare block in a flash memory to which the control method of the second embodiment is applied. FIG. 7 is a flowchart for explaining the operation of the second embodiment. FIG. 8 is a diagram showing a schematic configuration of a video camera using a conventional flash memory. [Description of References] P0 ... P block, C0 to C3 ... C block, 1 to 32
... Block, 41 ... Data block code storage unit, 4
2. Reserve block code storage unit.

Continuation of front page (56) References JP-A-2-104078 (JP, A) JP-A-2-122784 (JP, A) JP-A-2-226977 (JP, A) JP-A-3-27455 (JP) JP-A-64-41042 (JP, A) JP-A-5-313989 (JP, A) JP-A-6-95955 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G06F 12/00-12/06 G11C 16/02 H04N 5 / 76,5 / 80-5/907

Claims (1)

(57) Claims 1. A plurality of blocks having the same storage capacity, a first block having m sets of at least n clusters, and a first block having n clusters While having m number of second blocks, image data in a high compression mode is recorded by one cluster constituting each set of the first block and one cluster of the second block,
A cluster forming the set of the first block and the second
In the flash memory in which the image data in the low compression mode is recorded by all the clusters of the block, the cluster of the erased image is in any one of the sets of the first block and the corresponding set other than the erased image is included in the corresponding set. If there is no recorded cluster, the cluster of the erased image is erased, and the cluster of the erased image is in any one of the sets of the first block, and the corresponding set has a recorded cluster other than the erased image and has the erased image. If there are recorded clusters other than the erased image in the second block, the recorded clusters other than the erased image of the first block are replaced with empty clusters of another set, and the recorded clusters other than the erased image of the second block are recorded. After copying the clusters to the empty clusters of the other second block, the clusters of the erased image and the copied clusters are erased. Control method of Sshumemori.