JP2010122947A - Information recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce loss of information even when a sudden stop of power supply occurs during writing. <P>SOLUTION: An information recording device has: a means for receiving movement-related information related to movement of a moving body; a first nonvolatile memory for temporarily recording the movement-related information; a second nonvolatile memory wherein time for completion of writing into a block of a writing completion block size that is a minimum unit wherein the writing is completed is longer than the first nonvolatile memory; a writing means for writing the movement-related information into the first nonvolatile memory, and bringing it into a holding state; a means of reading the movement-related information of the same size as the writing block size of the second nonvolatile memory from the first nonvolatile memory; a means of writing the read movement-related information into the second nonvolatile memory; and a means of confirming normal completion of the writing into the block of the writing completion block size, and thereafter releasing the holding state of the movement-related information whose writing is normally completed of the movement-related information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an information recording apparatus for recording movement related information related to movement of a moving object.

  As an information recording device that records information related to a moving object, for example, a drive recorder is a device that records driving information such as moving images taken by a camera in a nonvolatile memory before and after the occurrence of an accident by a vehicle. .

In Patent Document 1, a moving image captured by a camera is temporarily stored in a volatile memory, and when a collision is detected by a sensor, the moving image stored in the volatile memory is stored in a nonvolatile memory. A drive recorder for recording is disclosed.
JP 2007-334760 A

  A storage device that records movement-related information such as driving information of an information recording device that records information related to a moving object such as a drive recorder is NAND-type so that it cannot be broken and cannot be read due to the impact of an accident. It is desirable to use a non-volatile semiconductor memory such as a flash memory or an MRAM.

  In addition, even if the drive recorder suddenly becomes inoperable due to the power supply being stopped or the circuit board being damaged due to the impact of an accident, the operation information recorded until immediately before is not stored in the nonvolatile memory. It should be recorded on the device and read after the accident.

  Therefore, when a NAND flash memory is used as an operation information recording device of an information recording device that records information related to a moving body, such as a drive recorder that satisfies such requirements, a writing method unique to the NAND flash memory is used. It is necessary to consider.

  The NAND flash memory reads and writes data in units called pages, and erases data in units called blocks in which a plurality of pages (for example, 64 pages and 128 pages) are combined. The page size is, for example, 2 Kbytes or 4 Kbytes, and the block size is, for example, 128 Kbytes or 256 Kbytes. When writing a page to the NAND flash memory, a write command, an address to be written, and data of a page size to be written are sent to instruct the write. Thereafter, a status read command is sent and the status is read to check whether the writing has been completed normally. At this time, if the writing is not completed normally, it is necessary to invalidate the entire block to which the page belongs and write the data again in another block. In other words, there is a possibility that writing of the entire block is required again until it is confirmed that the writing of the entire block has been normally completed.

Therefore, when an information recording device that records information related to a moving object, such as a drive recorder, stops operating due to an accident or the like before writing is completed normally up to the last page of the block, writing was in progress at the time of stopping. There is a possibility that the page writing does not end normally and the entire block must be invalidated. As an example, when the drive recorder records a moving image at a bit rate of 2 Mbps, 256 Kbytes of data are recorded in the NAND flash memory per second. At this time, if the block size is 256 Kbytes, one second of data corresponds to one block. Therefore, there is a possibility that a moving image for a maximum of 1 second immediately before the accident cannot be read correctly. As described above, in a NAND flash memory or the like, finally, it takes time to write information to the memory that stores information related to the movement of the moving object, and even if the power supply suddenly stops during writing, There arises a problem that defects occur. These problems are not limited to the NAND flash memory.

  In order to achieve the above object, an information recording apparatus according to an embodiment of the present invention is an information recording apparatus attached to a moving body, and includes a receiving means for receiving movement related information related to movement of the moving body, A first nonvolatile memory that temporarily records related information and a time for completing writing to a block having a write completion block size that is a minimum unit for completing writing is longer than that of the first nonvolatile memory. Two nonvolatile memories, first writing means for writing the received movement-related information to the first nonvolatile memory and holding the movement-related information, and a writing block size of the second nonvolatile memory; Reading means for reading movement-related information of the same size from the first nonvolatile memory, and movement-related information read by the reading means is second nonvolatile The movement-related information in which the writing has been normally completed among the movement-related information after confirming that the writing to the block having the writing completion block size of the second nonvolatile memory and the second writing means to be written to the memory has been normally completed. And holding state releasing means for releasing the holding state.

  According to the present invention, it takes a long time to write to the memory that stores information related to the movement of the mobile object, and the loss of information is reduced even when a sudden power supply stop occurs during the writing. Can do.

  FIG. 1 is a diagram showing a system configuration example of an information recording apparatus 100 of the present invention.

  The CPU 103 controls the entire information recording apparatus 100, and a program executed by the CPU 103 is recorded in a ROM 104 connected to the CPU 103 via a bus 108, and a RAM 105 stores data necessary for the CPU 103 to execute the program. An MRAM 105 is connected to the bus 108 as a first nonvolatile memory, and a NAND flash memory is connected to the bus 108 as a second nonvolatile memory. It should be noted that the ROM 104 and the RAM 105 may be assigned to the MRAM. The movement related information detection unit 101 is connected to the bus 108 via the interface 102.

  FIG. 2 is a functional block diagram of the information recording apparatus 100 of the present invention.

  The information recording apparatus 100 includes a movement related information detection unit 101, a reception unit 202, a first nonvolatile memory 106, a second nonvolatile memory 107, a first writing unit 203, a reading unit 204, and a second writing unit 205. The holding state releasing means 208 is provided.

  The information recording apparatus 100 is attached to a moving body (not shown). Here, the moving body refers to a moving machine such as a vehicle, an aircraft, and a ship, but is not limited thereto.

  The movement related information detection unit 101 detects movement related information related to the movement of the moving object. Here, the movement related information is information related to the movement of the moving body, and the information related to the movement is information indicating the surrounding situation of the moving body when the moving body moves, Information indicating the movement status of the moving body itself when moving. Examples of the information representing the surrounding state of the moving object include a moving image obtained by photographing the periphery of the moving object, distance information with respect to the moving object that moves before and after being detected by ultrasonic sonar and the like. Examples of information representing the movement status of the moving body itself include speed information obtained by an acceleration sensor and information representing the operation status of a brake or a handle.

  The accepting unit 202 accepts the movement related information detected by the movement related information detecting unit 101.

  The first nonvolatile memory 106 is a memory that temporarily records movement-related information.

  The second non-volatile memory 107 is a non-volatile memory that takes longer to complete writing to a block having a write completion block size, which is the minimum unit for completing the writing, than the first non-volatile memory. Here, if the writing is not completed, the information written halfway is not normally written, so that the information is practically lost. Therefore, since the second nonvolatile memory 107 has a longer write time than the first nonvolatile memory, the second nonvolatile memory 107 is in the middle of writing due to an accident or the like. It can be said that there is a higher possibility that information written halfway will be lost due to the stop of power supply, compared to the first nonvolatile memory.

  For example, the first nonvolatile memory is a magnetic random access memory (MRAM), and the second nonvolatile memory is a NAND flash memory.

  The first writing unit 203 writes the movement related information received by the receiving unit 202 to the first non-volatile memory so as to hold the movement related information. Here, the state of holding means that the movement related information and the holding necessity determination information for determining whether to hold the movement related information are stored in association with each other, and the movement related information for which the holding necessity determination information is required is stored. Information refers to a state in which the first writing means 203 cannot be deleted or overwritten.

  The reading unit 204 reads movement-related information having the same size as the writing block size of the second nonvolatile memory from the first nonvolatile memory. Specifically, the movement-related information stored in the first non-volatile memory is data that has not yet been written to the second non-volatile memory, from the beginning of the writing order of the first non-volatile memory. Read data of the write block size of the second nonvolatile memory. Here, the write block size of the second nonvolatile memory is the minimum unit (size) when writing to the second nonvolatile memory. Therefore, the above-described write completion block size is larger than the write block size, and the write completion block size is a size in which a plurality of write block sizes are collected.

  The second writing unit 205 writes the movement related information read by the reading unit 204 to the second nonvolatile memory.

  After confirming that the writing to the second nonvolatile memory 107 has been normally completed, the holding state releasing unit 208 releases the holding state of the movement related information that has been normally written out of the movement related information. Here, the writing to the second nonvolatile memory 107 is normally completed means that the writing to the block having the writing completion block size, which is the minimum unit for completing the writing, is normally completed.

  In addition, the successful completion of the writing to the second nonvolatile memory 107 indicates that the deletion enabling means 208 sends a status confirmation request to the second nonvolatile memory 107 and based on the returned status and the like. Check. Also, releasing the holding state means making the movement-related information to be released a state that may be deleted or overwritten. For example, another information can be written in the storage area in which the movement related information to be released is stored.

  Next, the operation of this embodiment will be described.

  The movement related information detection unit 101 detects movement information such as a moving image. The detected movement information is received by the receiving unit 202, and the first writing unit 203 writes the movement-related information in the holding state at the same time as writing to the first nonvolatile memory 106.

  Then, when the movement related information having the same size as the writing block size of the second non-volatile memory is accumulated in the first non-volatile memory, the reading unit 204 reads out from the first non-volatile memory, The writing unit 205 writes in the second nonvolatile memory.

  When the holding state releasing unit 208 confirms that the writing to the second nonvolatile memory 107 has been normally completed, the holding state releasing unit 208 releases the holding state of the movement-related information for which the writing has been normally completed.

  Next, an implementation example of this embodiment will be described below as an example.

  FIG. 3 shows a system configuration example of a drive recorder which is an embodiment of the information storage device of the present invention. The CPU 103 controls the entire drive recorder 300, and a program executed by the CPU 103 is recorded in a ROM 104 connected to the CPU 103 via the bus 108, and a RAM 105 stores data necessary for the CPU 103 to execute the program. An MRAM 306 is connected to the bus 108 as a first nonvolatile memory, and a NAND flash memory 307 is connected to the bus 108 as a second nonvolatile memory. It should be noted that the ROM 104 and the RAM 105 may be assigned to the MRAM 306.

  A moving image captured by the camera 301-1 is read through the camera interface 302-1 connected to the bus 108 and recorded in the MRAM 306. Here, an example of the movement-related information detection unit 101 is the camera 301-1, an example of the reception unit 202 and the first writing unit 203 corresponds to the camera interface 302-1, and the first nonvolatile memory 106. The example corresponds to the MRAM 306. FIG. 3 shows a configuration having two cameras 301-1 and two camera interfaces 302-1, but each may be one, or three or more. The camera interface 302-1 may be configured to directly write moving image data to the MRAM 306 by DMA (Direct Memory Access), or the CPU 103 may read moving image data via the camera interface 302-1 and write it to the MRAM 306. Alternatively, a dedicated data transfer path may be provided between the camera interface 302-1 and the MRAM 306 to write a moving image.

  The drive recorder 300 may have a sensor interface 302-2 for taking in various types of data regarding the driving situation in the vehicle via the sensor 301-2. By recording these data together with the moving image photographed by the camera 301-1, it can be used for investigating the cause when an accident occurs. The data captured by the sensor 301-2 includes speed information by an acceleration sensor, data indicating an operation state such as a brake, distance information with respect to a vehicle traveling before and after being detected by an ultrasonic sonar or the like. In particular, speed information and distance information are important for detecting the occurrence of an accident. Here, in the case where the camera interface 302-1 directly writes moving image data to the MRAM 306 by DMA (Direct Memory Access), the sensor 301-2 corresponds to an example of the movement related information detection unit 101, and the sensor interface 302-2. Corresponds to an embodiment of the accepting means 202 and the first writing means 203. When the CPU 103 reads the moving image data via the camera interface 302-1 and writes it into the MRAM 306, the sensor 301-2 corresponds to the embodiment of the movement related information detection unit 101, and the sensor interface 302-2 corresponds to the reception unit 202. Corresponding, the CPU 103 (meaning CPU executed based on a predetermined program) corresponds to the first writing means 203.

  FIG. 4 shows another configuration example of the drive recorder 400 of the present invention. In the configuration of FIG. 3, a NAND flash memory 307 is connected to the bus 108 of the CPU 103, and the CPU 103 directly controls. On the other hand, in the configuration of FIG. 4, a card (for example, a compact flash (registered trademark), an SD card, etc.) on which the NAND flash memory 307 is mounted is connected to the CPU 103 via a flash memory controller. In this configuration, the NAND flash memory 307 as the second nonvolatile memory can be freely inserted and removed. 3 and FIG. 4 operate in the same manner.

  An operation procedure in the configuration of FIGS. 3 and 4 will be described. A moving image captured by the camera 301-1 is input via the camera interface 302-1 and sequentially written in the MRAM 306 (corresponding to the first writing unit). The MRAM 306 is managed as shown in FIG. An operation information recording area for recording operation information is provided on the MRAM 306. This operation information recording area is a ring buffer, and pointers pointing to the head and the end are provided on the MRAM 306. Further, when data is written from the MRAM 306 to the NAND flash memory 307, the address of the write destination block is recorded on the MRAM 306.

  The driving information is time-series data composed of a moving image captured by the camera 301-1 connected to the drive recorder 400 and data captured by the various sensors 301-2 (corresponding to movement-related information). FIG. 5 shows an example in which driving information is recorded when only one camera 301-1 is connected to the drive recorder (300 or 400), and the image of each frame constituting the moving image is displayed as a ring. Recorded sequentially in the buffer. For example, in the case of a moving image captured by the camera 301-1 at 30 frames / second, 30 images are captured per second, and are sequentially recorded in the ring buffer.

  The captured image may be recorded as driving information without being compressed, or may be recorded as driving information after being compressed by the CPU 103 for each image by JPEG or the like. Alternatively, the compressed image may be captured and recorded as operation information using the camera 301-1 or the camera interface 302-1 provided with compression hardware. Also, data obtained by compressing a plurality of frame groups together using a moving image compression technique such as MPEG may be recorded as operation information.

  When a plurality of cameras 301-1 are connected, or when sensor data other than moving images are recorded simultaneously, they are alternately recorded in the ring buffer. At this time, it is desirable to know what data is read when it is read out, for example, by recording together appropriate header information. For example, the identification information of the movement-related information detection unit 101 such as the sensor 301-2 or the camera 301-1 is associated with the data to determine what data.

  Since the operation information recording area on the MRAM 306 is used as a ring buffer, a “buffer start” indicating the start position of data recorded in the ring buffer and a “buffer end” pointer indicating the position of the last written data. Manage. These pointers are preferably stored on the MRAM 306 so that they are not lost even if the power supply is stopped due to an accident or the like. The “end of buffer” pointer is updated each time new driving information is recorded in the ring buffer.

  The operation information recorded in the operation information recording area on the MRAM 306 is sequentially copied to the NAND flash memory 307 (corresponding to the reading means and the second writing means). This is because the NAND flash memory 307 is generally low-cost and large-capacity compared to the MRAM 306, and is therefore suitable for final operation information recording. FIG. 6 shows a procedure for copying data from the MARM to the NAND flash memory 307.

  Basically, copying is performed in units of the block size of the NAND flash memory 307, and the copy source data is kept in the MRAM 306 until it is confirmed that the copying has been completed normally. Even when the drive recorder (300 or 400) is generated and the drive recorder is stopped, the data until immediately before the accident is controlled to always remain in either the MRAM 306 or the NAND flash memory 307.

  Here, the data transfer from the MRAM 306 to the NAND flash memory 307 is performed according to the procedure of FIG. First, a block for recording the next data is secured on the NAND flash memory 307, and its address is recorded as “NAND block address” information on the MRAM 306 (S1). The securing of this block can be realized by creating a list of unused blocks in advance and sequentially taking out the list. If all the blocks are used and there is no empty block, the data of the block in which the oldest operation information is recorded is erased and the block is used.

  Next, data having the same size as the page size of the NAND flash memory 307 is extracted from the operation information recording area on the MRAM 306 from the top of the data that has not yet been written to the NAND flash memory 307 (corresponding to the reading means) (S2 ).

  The data is written in the first page not yet written in the writing block allocated on the NAND flash memory 307 (corresponding to the second writing means) (S3). This writing can be realized by sending a data write command, a write destination page address, and write data to the NAND flash memory 307. When writing to a card equipped with the NAND flash memory 307 as shown in FIG. 4, the write destination address may be a logical address.

  When the writing is completed, a status read command is sent to the NAND flash memory 307 to read the status (S4).

  When the read status indicates that the writing has been completed normally (S5), it is checked whether or not the page written at that time is the last page of the block (S6). , Jump to S2 and continue writing the next page. If it is the last page, it indicates that the writing of data for the block size to the NAND flash memory 307 has been completed normally, so the data for the block size is released from the beginning of the operation information recording area on the MARM. A possible state is set (corresponding to the holding state releasing means 208). This operation can be realized by advancing the “head of buffer” pointer by the block size.

  If the writing to the NAND flash memory 307 is not successful in S5, it is necessary to allocate a new block according to the specifications of the NAND flash memory 307 and rewrite the entire block including the page that cannot be written again. For this reason, all writing to the page in the current block is canceled (S8), and the process starts again from where a new block is allocated in S1.

  In the embodiment of FIG. 5, the beginning and end of the ring buffer in the driving information recording area are stored as pointers. However, by analyzing the data recorded in the driving information recording area, for example, a time stamp included in the image data When the head and end of the data in the ring buffer can be determined from such information, the pointers at the head and end of the ring buffer may be stored in the volatile RAM instead of the MRAM 306.

  By carrying out in this way, even when the power supply to the drive recorder (300 or 400) is stopped due to the occurrence of an accident or the board of the drive recorder (300 or 400) is destroyed and the function is stopped, The operation information up to immediately before is left in the NAND flash memory 307 or in the operation information recording area on the MRAM 306. Desirably, when the power of the drive recorder (300 or 400) is turned on for the first time after an accident, information starting from the position indicated by the “head of buffer” pointer in the operation information recording area in the MRAM 306, and the NAND flash memory 307 Compare the data recorded in the block specified by the block address recorded in “NAND block address” to determine whether the data for one block has been written correctly. If the same block can be continuously written, the writing is continued. Otherwise, a new block is allocated and rewriting is performed.

  In the management method of the MRAM 306 shown in FIG. 5, the size of the ring buffer in the operation information recording area needs to be at least the same as or larger than the block size of the NAND flash memory 307.

  It is also possible to increase the size of the operation information recording area and record only the data before and after the occurrence of the accident in the NAND flash memory 307. For example, a driving information recording area having a size capable of recording driving information for about 20 seconds is prepared, and normally the driving information is continuously recorded in the ring buffer of the driving information recording area. At this time, if the ring buffer becomes full, the old operation information is overwritten. When an accident is detected by information such as an acceleration sensor, the oldest information in the current driving information recording area is written in the NAND flash memory 307 in order. Thereafter, the operation information is continuously written in the NAND flash memory 307 until a certain time has elapsed since the occurrence of the accident. In this way, the number of writes to the NAND flash memory 307 can be greatly reduced.

  FIG. 7 is a diagram showing a data management method on the MRAM 306 of another embodiment. In this embodiment, similar to the embodiment of FIG. 5, moving images taken by the camera 301-1 are sequentially captured and recorded in the driving information recording area. Next, the data recorded in the driving information recording area is compressed by the CPU 103 or dedicated hardware to create compressed image data, which is recorded in the compressed driving information recording area. This compressed operation information recording area is also managed as a ring buffer, and the beginning and end of valid data are indicated by two pointers of “the head of the compression buffer” and “the end of the compression buffer”. In the NAND flash memory 307, the compressed image data recorded in the compressed operation information recording area is written in block size units.

  At this time, the address of the block of the NAND flash memory 307 to which data is written is recorded in the “NAND block address” area on the MRAM 306 as in the example of FIG. By carrying out in this way, the amount of data to be recorded in the NAND flash memory 307 can be reduced, and even longer data can be recorded with the same capacity.

  For compression, a moving image compression technique such as MPEG may be used, or other file compression techniques may be used. FIG. 7 shows an embodiment in which compressed image data is recorded in the compressed driving information recording area. However, when the driving information recorded in the driving information recording area includes sensor data in addition to the moving image, The compressed data may be recorded in the compressed driving information recording area, or only the moving image portion in the driving information is compressed, and other sensor data is not compressed. It is also possible to carry out recording as it is.

  FIG. 7 shows an implementation method in which both the operation information recording area and the compressed operation information recording area are secured on the MRAM 307. As another implementation method, the compressed operation information recording area may be provided on a volatile RAM. This is because if the data in the operation information recording area is in a non-volatile memory, the data can be reproduced in the compressed operation information recording area.

  As another implementation method, similarly to FIG. 7, both the operation information recording area and the compressed operation information recording area are secured on the MRAM 307, and the operation information recorded in the compressed operation information recording area after being compressed is Then, the operation information recording area is opened. By doing so, it is possible to reduce the amount of memory required for the operation information recording area.

  As another implementation method, as shown in FIG. 7, the MRAM 307 is managed and a means for detecting the occurrence of an accident by an acceleration sensor or the like is provided. If no accident has occurred, data in the compressed operation information recording area is stored. Is continuously written in the NAND flash memory 307, and data in the operation information recording area is written in the NAND flash memory 307 before and after the accident occurs. By doing this, it is possible to continue writing data with a high compression rate during normal times, and to record clear images with no compression or low compression rate before and after the accident.

  Although the embodiment using the MRAM 307 as the first nonvolatile memory has been shown, other implementations are possible using a nonvolatile memory such as FeRAM, battery-backed SRAM, ReRAM, PRAM, and NOR flash memory. it can. At this time, the present invention can be more effectively implemented when the write block size of the first nonvolatile memory is smaller than the write block size of the second nonvolatile memory. For example, since the MRAM 307 can be written randomly, the write block size is the data width of the memory, for example, 1 word (32 bits).

  Although the embodiment has been described using the NAND flash memory 307 as the second nonvolatile memory, other than that, a nonvolatile memory such as a ReRAM or NOR flash memory, an HDD, an optical disk, a magneto-optical disk, or the like is used. Can be similarly implemented.

The system block diagram of embodiment of this invention. The functional block diagram of embodiment of this invention. The system block diagram of the Example of this invention. The another system block diagram of the Example of this invention. The figure which shows the management method on MRAM of the Example of this invention. The figure which shows the procedure of the data copy of the Example of this invention. The figure which shows the data management method on MRAM of another Example of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Information recording apparatus 101 ... Movement related information detection means 106 ... 1st non-volatile memory 107 ... 2nd non-volatile memory 202 ... Acceptance means 203 ... 1st writing Means 204 ... Reading means 205 ... Second writing means 208 ... Holding state releasing means

Claims (7)

An information recording device attached to a moving body,
Receiving means for receiving movement-related information related to movement of the moving body;
A first nonvolatile memory for temporarily recording the movement related information;
A second nonvolatile memory in which a time for completing writing to a block having a write completion block size, which is a minimum unit for completing writing, is longer than that of the first nonvolatile memory;
A first writing means for writing the received movement-related information to the first nonvolatile memory and setting the holding state to hold the movement-related information;
Reading means for reading movement-related information having the same size as the writing block size of the second nonvolatile memory from the first nonvolatile memory;
Second writing means for writing movement-related information read by the reading means to the second nonvolatile memory;
After confirming that writing to the block having the write completion block size of the second nonvolatile memory has been normally completed, the holding of the movement related information that has been normally written among the movement related information is released. An information recording apparatus comprising: a state opening unit. The information recording apparatus according to claim 1, wherein the movement related information is a moving image captured by a camera. The information recording apparatus according to claim 1, wherein the movement related information is a movement state of a moving body detected by a sensor. 2. The information recording apparatus according to claim 1, wherein the storage capacity of the first nonvolatile memory is at least equal to or larger than the write completion block size of the second nonvolatile memory. Write position information indicating a correspondence between a storage position of the movement-related information in the first nonvolatile memory and a position where the movement-related information is written in the second nonvolatile memory is stored in the second nonvolatile memory. The information recording apparatus according to claim 1. Immediately after the power is turned on, it is determined whether the block data is normally written from the first nonvolatile memory to the second nonvolatile memory based on the writing position information. 5. The information recording apparatus according to claim 4, wherein writing is performed again in the second nonvolatile memory. A compression unit for compressing the moving image read by the reading unit;
3. The information recording apparatus according to claim 2, wherein the second writing unit writes the compressed moving image in the second nonvolatile memory.

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