JP2675429B2 - Data management method for memory card - Google Patents

Description

TECHNICAL FIELD The present invention relates to a memory card for storing data such as image data, and more particularly to a data management system for managing a storage state of the data.

2. Description of the Related Art In recent years, for example, in digital electronic still cameras, a smaller memory card using a semiconductor memory has been used instead of a floppy disk as a medium for recording image data representing a captured image.

In such a system using a memory card, a method of storing the management data indicating the memory storage order and memory storage for each image is
The present applicant has filed a pending patent application, Japanese Patent Application No. 62-120073. In addition, a pending patent application by the same applicant as this application, Japanese Patent Application No. 1-10997, proposes a memory management system capable of efficiently storing variable size data. According to this memory management system, the storage area of the memory card is divided into a plurality of clusters (storage units), and the storage of information is managed for each cluster. Although the image information of the frame is stored, the related information is designated by the memory allocation table (MAT), and the information of the cluster in which the beginning portion of the image information of one frame is stored is designated by the directory. .

In a memory card adopting such a conventional data management system, management data such as a management table called MAT and a directory is stored in, for example, the beginning area of the memory area of the memory card, and the electronic still camera side Then, the information of the management area is read out, the storage location of the image data to be newly stored in the memory card is determined, and new management information is also created and stored in the memory card.

By the way, as a memory card used in such a system, conventionally, a static RAM (SRAM) capable of high-speed reading and writing has been used. However, since this SRAM is a volatile semiconductor memory, it requires a backup battery,
Further, there has been a problem that the storage of a large amount of data such as image data is expensive and the cost of the card is high. Therefore, in recent years, EE is a non-volatile semiconductor memory that is inexpensive and does not require a backup battery.
The adoption of PROM (electrically erasable and rewritable read-only memory) for a memory card is under consideration. This EEPROM has an excellent storage time of 10 years or more without a battery, and in recent years it has come to have a read or write speed comparable to SRAM, and the price is about a quarter of SRAM. Is being developed.

However, this EEPROM requires a two-step operation of once erasing the previously written data and then writing when rewriting, and the erasing method is a batch erasing type (flash Type) and block-based erasing. An EEPROM that erases in block units can be rewritten in block units, similar to SRAM. However, when the conventional data management method as described above is adopted for this EEPROM, since only one header is provided in the management area of the memory card, the system cannot be rewritten while the management information is being rewritten. When an accident such as a power failure occurs on the (camera) side, the management information is erased. Therefore, in the worst case, the management information may be completely lost. If the management area is completely lost, the contents of the card cannot be expanded to the outside, and there is a risk that the memory card cannot be used thereafter.

Aim The present invention solves the drawbacks of the prior art as described above, and when an accident occurs when writing management information for managing the storage state of data to a memory card, the management information can be completely saved even in the worst case. It is an object of the present invention to provide a memory card and a data management method for the memory card, in which the safety of the memory card is improved without loss.

DISCLOSURE OF THE INVENTION According to the present invention, in a memory card that is detachably formed in a host processing device and stores data sent from the host processing device, a storage area of the memory card has a storage capacity of a predetermined storage capacity. The storage area is divided into units, and at least two or more management areas for storing management information for managing the storage state of the data accumulated for each storage unit are formed.

Further, according to the present invention, in a data management system in a memory card which is detachably formed in a host processing device, stores data sent from the host processing device, and also stores management information of the data, The card has at least two management areas for storing management information for managing the storage state of the data, and the host processing device, when rewriting the data of the memory card, stores the previous data stored in the memory card. Is read out from one management area of the memory card, management information relating to rewriting of data this time is created, and the management information is written in at least two management areas with a time lag.

Further, according to the present invention, in the data management system in the memory card which is detachably formed in the host processing device, stores the data sent from the host processing device, and also stores the management information thereof. Has at least two management areas for storing management information for managing the storage state of data, and when rewriting data, this memory card stores the management information after the rewriting in one management area. It is characterized in that the management information written in one management area is transferred to another management area after the writing and the current management information is stored in at least two management areas.

Description of Embodiments Embodiments of a memory card and a data management system in the memory card according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the memory card 10 in this embodiment includes a storage unit 1 for storing data, a controller 3 for controlling writing or reading data in the storage area, an electronic still camera, etc. Of the host processing device of FIG.
The storage unit 1 includes two data management areas 16A and 16B.

The storage unit 1 is composed of a block erasing type EEPROM. The storage area of this EEPROM is divided into clusters 14 each having a predetermined storage capacity, as shown in FIG. This EEPROM is erased in cluster units. A first management data area 16A in which management information of image data is stored is allocated to the first cluster (# 1) of the cluster 14, and a second management data area 16B is allocated to the next cluster (# 2). It is assigned. The remaining area of the storage area is used as an image data area 20 for accumulating image data. The capacity of the cluster 14 is, for example, data necessary for representing one image by a video signal in a standard format, which is called "packet" (Fig. 3). May be accumulated. The packet 22 may be interpreted as a unit including audio data related to image data.

A header 16a, a packet attribute 16c, a directory (DIR) 16d, and a memory allocation table (MAT) 16e are stored in the management data areas 16A and 16B, respectively.

In this embodiment, basically, one packet of image data 22
Are stored in an arbitrary cluster 14. In the MAT area 16e, data indicating related information of the cluster 14 in which one packet of image data 22 is stored, that is, MAT data is stored. MAT
The data is, for example, for the cluster 14 in which a part of the image data 22 of the packet is accumulated as shown in FIG.
It contains identification information, eg a number, of the cluster 14 in which the remaining image data directly connected to it is stored. When there is no remaining image data, a predetermined code, for example, "all 1s" (binary value), indicates that the cluster 14 is the last of the packet 22. More specifically, 2 bytes per cluster are used in the MAT area 16e, and the number of the cluster 14 following this is stored. The value of MAT16e is
In the present embodiment, "all 0s" are set when the image data is not stored in the cluster 14, for example, in the unused state or the erased state, and at the end of the packet 22, another predetermined code, for example, ""1", that is, "FFFF" in hexadecimal. Other clusters following this for its packet 22
If 14 exists, it takes a value indicating the number of the continuous cluster 14.

Information indicating the start cluster and the data type is stored in the directory area 16d. The start cluster information is a cluster in which the first one of the image data is accumulated for each image, that is, for each packet 22.
The identification information points to 14, for example, the start cluster number. In this way, it is specified in which cluster 14 the image data of one image is stored. The information indicating the data type indicates the type of information stored in the storage unit 1, and indicates, for example, image data, audio data, character data, or a program.

For example, when the storage capacity of the storage unit 1 is 64 Mbits, the size of the cluster 14 is 64 Kbits, and 1024 clusters 14 can be provided. Numbers # 0 to # 1023 are assigned to each cluster 14 in the order of physical arrangement. Management areas 16A and 16B are allocated to the clusters # 0 and # 1, respectively, and store management data. In this embodiment, the management data includes a header 16a, a packet attribute 16c, a directory 16d and a MAT 16e, which are stored in their respective sub areas. Image data, for example, is accumulated in the remaining clusters # 2 to # 1023, and the image data also includes header information unique to each image.

One packet 22 is one or more clusters
Stored in 14. Therefore, the packet can be said to be a logical area in which image data representing one image is stored.
Packets 22 are numbered in a practical order such as the order of inputting image data, and when a packet 22 is deleted, the number becomes empty and is newly added to the image data to be stored next time or later. Granted. One packet of image data 22 is stored in one or more clusters 14. There may be an empty area 14a (FIG. 3) in the last cluster 14. The capacity of the packet 22 that can be stored in the storage unit 1 is the number of the clusters 14 of the storage unit −2.

Therefore, one packet 22 is stored in the directory area 16d.
The number of the cluster 14 at the head of the is stored. In this embodiment, since the number of clusters is 1024, for example, 10 bits are used for the start cluster number and other bits are free. Unused directories are represented by "all zeros".

In this embodiment, further, a packet attribute area 16c is provided in each of the management data areas 16A and 16B. The packet attribute 16c includes information indicating whether or not the packet 22 is used for one packet 22, and may further include, for example, an indication indicating whether or not overwriting is possible, whether or not copying is possible, and whether or not reading is possible. More specifically, the packet attribute area 16c may take a bitmap method as shown in FIG. In this method, 1 bit is assigned to each packet, and each bit indicates whether the packet 22 has been used. In this example, 2
A hexadecimal "1" indicates used, and a "0" indicates unused. A specific packet position on the bitmap is indicated by the bitmap pointer 17.

FIG. 5 shows an example in which the packet attribute 16c is composed of 1 byte per packet 22, and 4 bits of each byte are used for displaying the packet attribute. Most significant bit MS
The first bit b1 of B indicates whether overwriting is possible, write protection is indicated by "1", and overwrite permission is indicated by "0".
In this case, overwriting may be interpreted as including erasing. The second bit b2 indicates whether the packet 22 is empty or closed, where "1" indicates used and "0" indicates unused. Furthermore, the third bit b3 is a bit indicating whether or not the information stored in the storage unit 1 can be copied, and the copy prohibition is "1".
, And the copy permission is indicated by “0”. Similarly, the fourth bit b4 indicates whether or not the information stored in the storage unit 1 can be read. The read prohibition is “1” and the read permission is “0”. For example, for a packet that cannot be used in storage area 20, the packet attribute
"11X1XXXX" is displayed as 16c. Here, "X" is a "don't care" bit.

The header 16a contains the number of used clusters, the number of remaining clusters,
The maximum used packet number, the head unused packet number, and the parity 16b are stored. The number of used clusters is data indicating the total number of clusters 4 in which image data is effectively written in the storage area 20. The number of residual clusters is
The number of clusters 14 that are available for writing image data in the storage area 20, that is, the number of empty clusters 14, is shown. Some ROM areas (not shown) of the memory card 10 store data indicating the capacity of the storage area. For such cards, the number of used clusters and / or the number of remaining clusters can be used to check the reasonableness of both in comparison with the storage capacity.

The maximum used packet number of the header 16a is data indicating the largest packet number of the packets 22 stored in the storage area 20. In this case, some of the packets in use may have been deleted,
Even in that case, the number with the largest value is the maximum packet number used. This is because when the memory card 10 is loaded into the playback device and the image data 20 is read, the playback device reads the packet attribute 16c and the directory 16d as described later, but uses them by referring to the maximum use packet number. The amount can be grasped, and thus the reading area can be limited. The head unused packet number indicates the number of the smallest unused packet in the storage area 20. The first unused packet number is
For example, when reproducing the image data 20 with the reproducing device, this can be written. This allows that memory card
When the electronic still camera 52 (FIG. 6) is loaded with the 10 to record an image, the processing load of the camera 52 can be reduced.

The header 16a may include the maximum used cluster number and the head unused cluster number in addition to or instead of the maximum used packet number and the head unused packet number. The maximum used cluster number is data indicating the largest cluster number among the clusters 14 in the storage area 20. In this case as well, there is a case in which some of the series of used clusters are not used, but even in this case, the number with the largest value is the maximum used cluster number. Further, the head unused cluster number indicates the number of the smallest unused cluster in the storage area 20.
The maximum used cluster number and the head unused cluster number also have the same effect as the case of the maximum used packet number and the head unused packet number described above.

The header 16 also includes a parity area. Header 16a
Contains 1 byte as a storage area specified by 1 address. The parity is calculated by calculating the parity in the address direction, that is, the vertical direction of the corresponding bit for each digit over all bytes of the header 16a, and is stored in the storage position of the final address of the header data area 16a. This calculation is accomplished by performing a binary addition for each digit to remove the carry. As a result, the validity of the data content of the header data area 16a can be checked. Although the parity check is used in the present embodiment, the present invention is not limited to this, and a check code system capable of error correction, such as a CRC code, may be used.

In addition to this, the header 16a may include a user area for storing user data such as a card number and a name that can be given to the memory card 10 by the user. In addition, a card 10 such as being a card for images
The format display data may be included in the identification display indicating the type. This format version data is used when the electronic still camera 52 is loaded with a memory card for data processing, when a memory card other than the initial type memory card 10 is connected to the recording device or the reproducing device, Used to protect cards.

By the way, as illustrated in the cluster # 4 of FIG.
The first cluster of a packet 22 includes data 14c indicating the image quality mode. The image quality mode 14c indicates an encoding compression mode of image and / or audio data forming the packet 22. For example, the total amount of image data for one packet differs depending on the standard mode or the encoding compression mode such as the high-density compression mode having a compression rate of 1 bit / pel, and thus the one packet is compressed. The required number of clusters 14 that can store image data is also different.
In this embodiment, when the image data 20 is stored in the memory card 10 by the recording device such as the electronic camera 52, the image quality mode 14
By writing c to the first cluster 14b of the packet 22, the reproducing device for reproducing the memory card 10 can identify the number of clusters 14 to be accessed during reproduction.

Referring again to FIG. 1, the controller 3 has a connector 5
In response to a control signal sent via the storage unit 1, a permission signal ES for writing and reading data to the storage unit 1 is sent, and an address signal AD sent via the bus 100 is sent to the storage unit 1. As control signals sent from the camera side, state signals A0 and A1 indicating the distinction between address signals or data signals sent via the bus 100, a read signal RD for reading data, a write signal for writing data. There are WR, a busy signal BUSY indicating an instruction in process to the camera side, and the like. Controller 3 in this embodiment
When the card 10 is attached to the camera 52 and the management data is read, after performing the control for reading the management data from one of the management areas 16A or 16B of the storage unit 10,
It has a function of sending a signal for erasing the management data in the area to the storage unit 1. In addition, when the above management data updated by the camera 52 is transmitted, the management area deleted
The management data is written in 16A or 16B, and when the writing is completed, the other management area is erased and the management data written in one management area is transferred to the other management area. The connector 5 is composed of, for example, a 20-pin connector according to the "IC memory card guideline" planned by the Japan Electronics Manufacturers Association (JEIDA).

An embodiment of a digital electronic still camera to which such a memory card 10 is applied is shown in FIG. In this figure, a memory cartridge 10 is detachably connected to a digital electronic still camera 52 by a connector 5.
This camera 52 has an imaging device 56 through an imaging lens 54.
It is a still image capturing device that captures an image of a field and stores the image data representing the field in the memory card 10. The output of the image pickup device 56 is subjected to signal processing such as color adjustment by the signal processing circuit 58, and the analog / digital (A /
D) Converted into corresponding digital data by the conversion circuit 60. This digital data is color-separated by the signal processing circuit 62, compression-encoded, and the data selector 64.
Through the connector 5 to the connector 5.

The camera 52 has an operation display unit 66, which manually inputs various instructions such as an exposure instruction, a data compression mode designation, and a write protect designation, and a space required for recording image data, for example. Display the device status to the user, such as an alarm indicating that there is no cluster. The instruction input to the operation display unit 66 is the system control unit 68.
The status of the device is sent from the control unit 68 to the operation display unit.
Given to 66.

The system control unit 68 is a control device that controls the operation of the entire camera 52, and also controls writing of data to the memory card 10.

A compression ratio setting circuit 70 is connected to the system control unit 68,
This is a circuit for setting, in the signal processing circuit 62, the coding compression rate of image data according to the data compression mode instructed by the operation display unit 66 under the control of the system control unit 68. As the compression encoding method, for example, orthogonal transformation such as two-dimensional cosine transformation, or sub sampling and quantization is advantageously applied.

The data selector 64 is a selection circuit that selectively sends the image data from the signal processing circuit 62 and the control data related to the system control unit 68 to the memory card 10 through the connector 50. 72 and the management area read circuit 74 are connected. Management area update circuit 72
Is a circuit for generating management data to be written in the management data areas 16A and 16B of the memory card 10. The management area read circuit 74 is a read circuit that reads the management data stored in the management area 20 of the memory card 10 and inputs it to the system control circuit 74.

In the operating state, when the memory card 10 is connected to the camera 52 by the connector 5, the system controller 68 causes the card 10 to operate.
The headers 16a to MAT16e stored in the data management area 16A (or the data management area 16B) of the storage unit 1 are sequentially read from the storage unit 1 of the card 10 via the management data reading circuit 74. This is because the addresses of the header areas 16a to MAT area 16e of the management area 16A are specified by the address specifying circuit 76 by the address specifying circuit 76, and the headers 16a to MAT16e read from the management data area 16A of the storage unit 1 are connected to the connector 5 by the connector 5. And is read by the management data read circuit 74 through the data selector 64. These management data are read from the management data area 16 and the system control unit
When sent to 68, the system control unit 68 sends the received signal to the memory card 10. In the memory card 10, when the received signal is received, a signal for erasing the contents of the management area 16A is sent from the controller 3 to the storage unit 1, and the management area 16A
Is prepared for writing the management data to be erased, updated and sent.

Upon receiving the management data, the system control unit 68 first checks the format version included in the read header 16a, and in the present embodiment, if the format version does not include an image display, the A display for rejecting the memory guard is displayed on the operation display unit 66. If the card number of the user is included, this is also displayed. Next, a parity check is performed on the header 16a, and the result is compared with the parity included in the header 16a. This parity check is, as mentioned above,
This is done by performing a binary addition for each digit in the address direction of the corresponding bit for each digit over all bytes of the header 16a and deleting the carry.

If the result of the parity check is good, the system control unit 68 checks the number of clusters. This is a check whether the total number of clusters in the storage area is calculated from the card capacity read from the memory card 10 and whether the total number of clusters is equal to the sum of the number of used clusters and the number of remaining clusters. The number of used clusters and the number of remaining clusters are 16
It is the management data included in a. If this check is passed, the system control unit 68 displays on the operation display unit 66 that shooting is possible.

When the shooting button is operated on the operation display unit 66, the system control unit 68 controls the imaging device 52 in response to the operation to shoot the object scene. The output of the image pickup device 52 is subjected to signal processing such as color adjustment in the signal processing circuit 58, and the analog signal is output.
The digital conversion circuit 60 converts the corresponding digital data. This digital data is the signal processing circuit.
The colors are separated by 62, compression-encoded at the compression rate set by the compression rate setting circuit 70, and output to the memory card 10 through the data buffer 63, the data selector 64, and the connector 50.

At that time, the system control unit 68 reads the MAT data 1
6e is used to search for a cluster in which the empty display "all 0s" is standing. The number of clusters required to store one packet 22 is calculated by the system control unit 68 from the compression rate instructed to the compression rate setting circuit 70. The system control unit 68
An address designating the beginning storage position of the required cluster 14 in the storage area 20 is generated and sent to the card 10.
In the card 10, the address designating circuit 76 generates a storage position address in each cluster 14 on the address bus 78, whereby the image data on the data bus 80 is written in the image data storage area 20. At that time, data indicating the image quality mode 14c corresponding to the compression rate is written in the first cluster 14b.

In this way, when the image data of one packet 22 and the audio data associated therewith are accumulated in the storage area 20, the system control unit 68 controls the management data update circuit 72 to update the MAT 16e. In other words, the MA used to record the data of one packet 22 is linked to the cluster 14
The number of the next cluster is entered in T16e corresponding to each cluster 14, and "all 1s" is entered in the final cluster. The management data update circuit 72 uses the MAT data 16e thus updated.
To the card 10, which is written to the management data area 16A.

Similarly, the directory 16d is updated. The directory 16d is updated for the data type and start cluster. Start cluster is 1 packet
The cluster number of the first one of the series of clusters 14 used for recording data 22 is created by the management data update circuit 72 and stored in the management data area 16A of the card 10.

The system control unit 68 then updates the packet attribute 16c. That is, the attribute display is set for the packet 22 stored in the card 10. In the bit map method shown in FIG. 4, the packet attribute bit of the stored packet 22 is set to the use indication “1”. In the method shown in FIG.
Set the air block b2 of the use display to "1", and the operation display
Depending on the state set in 66, overwrite permission b1, copy permission b3, and read permission b4 are set. This is also transferred to the management data area 16A.

Finally, the system control 68 rewrites the header 16a. Depending on the number of clusters required to store the data of one packet 22, the number of used clusters is added, the number of remaining clusters is reduced, and the head unused packet number is updated. Also, if there is a change in the maximum used packet number, this is also updated. The same applies to the top unused cluster number and the maximum used cluster number. Parity is created in the vertical direction of the corresponding bit for each digit for all the data of the header 16a that is updated in this way, and the parity 16
Update b. The updated header 16a is stored in the management data area 16
Written to A.

Thus, when storing the image data in the memory card 10, the image data 20, the MAT 16e, the directory 16d, the packet attribute 16c, and the header 16a are written in the memory card 10 in this order. At this time, if a situation occurs in which the card 10 is pulled out from the connector 5 in the middle of these series of operations, or if an unexpected accident such as power-off of the camera 52 occurs, it is not updated on the camera side. Although the management data will be lost, since the management data is stored in the management area 16B of the memory card 10 in this embodiment, the management data is read again to repeat the interrupted operation described above and update the latest data. Management data can be generated. In such a situation, when reading the management data from the management area 16B later, the management area 16B
Reads only the necessary part without erasing. As a result, later recording and reproducing operations of the card 10 are effectively performed. Then all management data updates are done,
When all the management data is stored in the management area 16A,
The controller 3 erases the management area 16B to replace the management area 1
The latest management data recorded in 6A is written in the management area 16B. This makes it possible to prepare for the next data update.

In the above embodiment, the management data is the header 16
Although a case has been described in which the management data is composed of four management data items a to MAT16e, the present invention is not limited to the number and method thereof, and may be any information as long as it is information for managing the stored data. A system provided with two or more management data is included in the present invention. Further, in the above embodiment, the description has been given by taking the EEPROM as an example of the storage unit of the memory card, but other semiconductor memory such as SRAM may be used.
Further, in the above embodiment, the management data updated in one management area is written in the other management area inside the memory card 10, but the management data updated from the camera side is again written in the other management area. It may be written.

Effect As described above, according to the present invention, at least two management areas for storing management information for managing the storage state of data are provided in the memory card. In the middle of writing,
Even if an accident such as power failure occurs, the management data is held in the other management area, so that the operation can be continued by reading the management data. Therefore, it is possible to prevent the loss of management data of the card, and solve the serious problem that the contents of the card cannot be expanded or the card cannot be used even in the event of an unexpected accident on the host side such as a camera. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a memory card according to the present invention, FIG. 2 is a diagram showing a configuration example of a storage area of a memory card in the embodiment of the present invention, and FIG. 3 is applied to the same embodiment. 4 and 5 are explanatory views illustrating the format of the packet attribute data in the configuration example of the storage area shown in FIG. 2, and FIG. 6 is a digital electronic still camera according to the present invention. It is a functional block diagram showing an example applied to. Description of main part code 1 …… Storage unit 3 …… Controller 5 …… Connector 10 …… Memory card 14 …… Cluster 14c …… Image quality mode 16A, 16B …… Management area 16a …… Header 16c …… Packet attribute 16d ...... Directory 16e ...... MAT (memory allocation table) 20 …… Image data 22 …… Packet 66 …… Operation display 68 …… System control

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-17852 (JP, A) JP 63-286077 (JP, A) JP 2-193236 (JP, A) Actual development Sho 63- 63879 (JP, U)

Claims (2)

(57) [Claims] 1. A detachable host processing device,
In a data management method for a memory card that stores data sent from the host processing device and also stores data management information, the memory card stores the same management information for managing a data storage state. Two areas are provided, and the host processing device reads the previous management information stored in the memory card from one management area of the memory card and rewrites it to the one management area when rewriting the data of the memory card. When the previous management information stored in the memory card is erased and the previous management information from the one management area read after the deletion is lost, the previous management information is deleted from the other management area of the memory card. The management information that is read out, updated management information relating to the rewriting of the current data is created based on the management information of the previous time, and the updated management information is set to the above-mentioned 2 Data management method in a memory card and writes each management area. 2. A host processing device which is detachably formed,
In a data management method in a memory card that stores data sent from the host processing device and also stores management information thereof, the memory card stores a management area for storing the same management information for managing a storage state of data. When the data is rewritten, the memory card is provided with two pieces of management information, and the management information after the rewriting is written in one management area, and after the writing, the management information written in the one management area is written in another area. A data management method in a memory card, wherein the current management information is written in a management area and the current management information is stored in the two management areas.