JP2006067172A - Event recording method and event recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an event recording method and an event recorder, which surely record a long-time video during movement as well as detailed videos before and after an accident and save the capacity of a storage device and facilitate analysis of a cause of the accident. <P>SOLUTION: An event recorder 10 is used wherein a compression means 17 for compressing a video photographed by an image pickup device 11, a high-speed recording means 18 for endlessly recording information compressed by the compression means 17 to a high-speed recording area 15 of a storage device 12, and a low-speed recording means 19 for thinning the compressed video at a certain rate to endlessly record the thinned video to a low-speed recording area 16 of the storage device 12 are provided between the image pickup device 11 and the high-speed recording area 15. The video photographed by the imaging means 11 is compressed, and compressed information is endlessly recorded to the high-speed recording area 15 of the storage device 12, and information read out from the oldest part of information recorded in the high-speed recording area 15 is thinned at a certain rate and is endlessly recorded to the low-speed storage area 16 of the storage device 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an event recording method and an event recorder that take an image of a surrounding situation from an installation position of an automobile or the like, and stop recording after an event such as an accident occurs to help reproduce and analyze the accident situation.

  2. Description of the Related Art Conventionally, an automobile event recorder has been devised for recording a situation when an automobile accident occurs and analyzing the cause of the accident later. In order to reproduce the situation at the time of the accident, recording with images is particularly important.

  For example, Patent Document 1 describes a safety drive recorder that can be continuously recorded by automatic repeat recording and that automatically stops due to an impact at the time of an accident. The automatic repeat video recording can be repeated every 2 to 6 hours. For example, a video deck for home use can record video for 2 hours or 6 hours by switching the video tape recording speed. The frame rate of such a recording apparatus is determined according to the standard. For example, the frame rate of NTSC (National Television System Committee), which is an international standard adopted in Japan and the United States, is 30 frames / second. Yes. The frame rate refers to the number of images recorded per second when a video is shot.

  In Patent Document 2, an image captured by a CCD camera is compressed and stored in a RAM. When an impact sound or the like is detected by a sensor, recording in the RAM is stopped and image data recorded in the RAM is recorded. And an automobile image recording apparatus for transferring clock data to a nonvolatile memory. When an accident occurs, the situation immediately before the accident can be reproduced later by data transferred from the RAM to the nonvolatile memory.

JP-A-11-142181 JP 2000-16352 A

  However, although the safety drive recorder described in Patent Document 1 records continuously for a long time, the video immediately after the accident is recorded in detail in a video at a general frame rate of about 30 frames / second. It is possible that the accident analysis will be difficult. For example, when a car at 60 km / h crosses in front of the camera, it moves about 55 cm between frames at 30 frames / second. For this reason, in order to record an accident, it is necessary to adopt a higher frame rate. However, if a high-speed camera is used to continuously record detailed images for a long time, the capacity of the storage device increases. Or there is a problem that the recording time is shortened.

  Moreover, although the image recording apparatus for automobiles described in Patent Document 2 can reproduce the situation immediately before the accident, it cannot reproduce the recording for a long time, and reproduces the driving situation up to the accident site and the sign of the accident. There is a problem that can not be. For example, when trying to record a 640 × 480 pixel VGA video, a color capacity of about 922 kbytes / frame is required, and when recording at a frame rate of 30 frames / second for 1 second, 28 Mbytes of memory are required. Become. By compressing the video, the capacity of the storage device can be saved. However, if the compression rate is increased, the video is deteriorated and detailed video cannot be recorded.

  As described above, in order to analyze an accident, it is necessary to record a video in detail and for a long time. However, such techniques as in Patent Documents 1 and 2 cannot achieve this.

  Therefore, the problem to be solved by the present invention is to reliably record the video up to the occurrence of an event such as an accident and the detailed video before and after the event, save the capacity of the storage device, and save the video at the time of the event. An object of the present invention is to provide an event recording method and an event recorder that facilitate reproduction and analysis of the cause of an accident.

  In order to solve the above problems, a first event recording method of the present invention includes an imaging device that captures an image, a storage device that records an image captured by the imaging device, an event detection device that detects an event, In an event recording method for recording video up to immediately after an event, the recording control means having a function of stopping recording to the storage device based on information from an event detection device, the image is taken by the imaging means The video is compressed, the compressed information is recorded endlessly in the high-speed recording area of the storage device, and the information read from the oldest part of the information recorded in the high-speed recording area is thinned out at a constant rate to reduce the low speed of the storage device Record endlessly in the storage area.

  Shooting by the imaging device is performed at a frame rate higher than 30 frames / second, and for example, it is preferable to shoot at 60 frames / second or more, preferably about 120 frames / second. Since the video is thinned out later and stored again, even if the video is stored at such a high frame rate, the memory capacity does not become insufficient.

  The video is compressed and continuously stored until the high-speed recording area is full, and then further overwritten in the high-speed recording area and recorded endlessly. For video compression, for example, an MPEG system, a RAPIC system, or the like can be used. Since the video is thinned out and stored again later, the video compression rate may be low, and high-quality video is stored.

  The video stored in the high-speed recording area is thinned out at a fixed rate before being overwritten and stored in the low-speed recording area. Similarly to the high-speed recording area, the low-speed recording area is overwritten and recorded endlessly. Here, “thinning out at a constant rate” means, for example, selecting and reading a predetermined frame from a large number of consecutive frames, and it is not always necessary to read all the frames, so that work can be performed at high speed. . Further, although the frame rate is reduced by the thinned-out amount, the image of each frame is not recompressed, so that a high-quality image having the same quality as the image quality of each frame stored in the high-speed recording area is stored.

  An event detection device detects events such as the occurrence of an accident. As the event detection device, for example, a sensor that detects a change in voice, acceleration, or the like can be used. Further, a manual input switch may be provided as the event detection device. In this case, the event can be recorded at an arbitrary timing.

  The recording control unit receives an event occurrence signal such as accident information from the event detection device, stops photographing after a certain time, and stops recording in the storage device. When the equipment is stopped, the high-speed recording area records detailed video at the time of the event at a low compression rate, and the low-speed recording area records video that was thinned during operation up to the accident site for a long time. It is recorded. Even when a power supply to the event recorder is interrupted due to an event such as a collision accident, data up to the event occurrence is recorded in the high-speed recording area and the low-speed recording area.

  According to a second event recording method of the present invention, there is provided an imaging device that captures an image, a storage device that records an image captured by the imaging device, an event detection device that detects an event, and information from the event detection device. Recording control means having a function of stopping recording to the storage device based on the above, and in an event recording method for recording the video immediately after the occurrence of the event, the video taken by the imaging means is compressed and compressed The video is recorded endlessly in the high-speed recording area of the storage device, and the compressed video is thinned out at a constant rate and recorded endlessly in the low-speed storage area of the storage device.

  The compressed video is stored at a high frame rate in the high-speed recording area and at a low frame rate in the low-speed recording area. Such a function can be realized by, for example, branching and outputting a compressed video, one of which is recorded as it is in the high-speed recording area, and the other is thinned out and then recorded in the low-speed recording area. it can. Access to the high-speed recording area is eliminated, and video can be recorded more smoothly.

  The event recorder of the present invention is based on information from an imaging device that captures an image, a storage device that records the image captured by the imaging device, an event detection device that detects an event, and the event detection device. An event recorder including a recording control unit having a function of stopping recording of video in the storage device, wherein the storage device includes a high-speed recording area and a low-speed recording area, and is provided between the imaging apparatus and the storage apparatus. A compression means for compressing the video imaged by the imaging device, a high-speed recording means for recording the information compressed by the compression means in a high-speed recording area of the storage device, and a compressed video image at a predetermined level. Low-speed recording means for performing endless recording in the low-speed recording area of the storage device by thinning out at a rate is provided.

  The video imaged by the imaging device is compressed by the compression means and recorded in the high speed recording area of the recording means by the high speed recording means. The low-speed recording means thins out the video directly input from the compression means or the video read from the high-speed recording area at a certain rate, and records it in the low-speed recording area of the storage device. When an event such as a collision accident occurs, this is detected by an event detection device, and video recording is stopped by the recording control means. When the apparatus stops, the video before and after the event is recorded at a high frame rate in the high-speed recording area, and the video until the event occurs is recorded in the low-speed recording area at a low frame rate.

  When the video input to the low-speed recording means is changed to the video output from the compression means, recording in the high-speed recording area and recording in the low-speed recording area are performed simultaneously. Further, access to the high-speed recording area by the low-speed recording means is eliminated.

  If the video input to the low-speed recording means is a video read from the high-speed recording area, the video is temporarily stored in the high-speed recording area, and after this is read out, the video is thinned out.

  When the compression means is provided with a function for compressing the video captured by the imaging device for each frame video, when thinning the video, each frame video can be thinned every predetermined number of frames, and the recording time of the adjacent frame video The interval of becomes constant.

  As the compression means, for example, a circuit that employs a compression method that performs compression for each frame image regardless of adjacent frame images, such as the RAPIC method, can be used. Since each frame image exists independently, for example, when it is desired that N frames have a capacity of 1 / n, only a frame image that is an integral multiple of n is read and stored in the low-speed recording area. When a video stored in the low-speed recording area is played back, the time interval between adjacent frame videos becomes constant, so that the video is played back smoothly.

  The event detection device is provided with time information generating means for generating time information and acceleration information detecting means for measuring acceleration, and when the time information and acceleration are recorded together with the video in the high-speed recording area, the time and the magnitude of the impact are recorded. Sato is played at the same time as the video. Since they are recorded in a superimposed manner, they are played back with no time lag from the video during playback.

  When the storage device is provided with a plurality of memories, and the high-speed recording area and the low-speed recording area are formed for each of the memories, the memory that forms the high-speed recording area has a high writing and reading speed. As the memory for forming the low-speed recording area, different types of memories can be used, such as a low-speed and inexpensive memory. Further, since it is not necessary for the recording control means to store the setting ranges of the high-speed recording area and the low-speed recording area, management of the storage device is simplified.

  When the storage device is provided with a single memory, and the capacities of the high-speed recording area and the low-speed recording area are variably set, when the total capacity of the memory is increased, the capacities of the high-speed recording area and the low-speed recording area are increased. Each time can be increased, and the time for high-speed recording and the time for low-speed recording can be lengthened.

The present invention has the following effects.
(1) Compressing the video imaged by the imaging means, recording the compressed information endlessly in the high-speed recording area of the storage device, and reading a certain percentage of information read from the oldest part of the information recorded in the high-speed recording area Since the video is recorded endlessly in the low-speed storage area of the storage device, the video can be recorded at a high frame rate in the high-speed recording area and at a low frame rate in the low-speed recording area. It is possible to reliably record the video and detailed video before and after the occurrence of the event, save the capacity of the storage device, and facilitate the reproduction of the video when the event occurs and the analysis of the cause of the accident.
(2) The video captured by the imaging means is compressed, the compressed video is recorded endlessly in the high-speed recording area of the storage device, and the compressed video is thinned out at a constant rate to endlessly in the low-speed storage area of the storage device. When recording, the video can be recorded in the high-speed recording area at a high frame rate and recorded in the low-speed recording area at a low frame rate, and access to the high-speed recording area by the low-speed recording means is eliminated. The load can be reduced, and the video up to the occurrence of an event such as an accident and the detailed video before and after the event occurrence are recorded reliably, the capacity of the storage device is saved, the playback of the video when the event occurs and the cause of the accident Can be easily analyzed.
(3) A high-speed recording area and a low-speed recording area are provided in the storage device, and between the imaging device and the storage device, a compression unit that compresses video captured by the imaging device, and information compressed by the compression unit is stored in the storage device High-speed recording means for recording endlessly in the high-speed recording area and low-speed recording means for thinly compressing compressed video at a constant rate and recording endlessly in the low-speed recording area of the storage device. Can be recorded at a high frame rate and at a low frame rate in a low-speed recording area, and the video up to the occurrence of an event such as an accident and the detailed video before and after the occurrence of the event can be recorded reliably. The capacity can be saved, and it is possible to easily reproduce the video at the time of the event and analyze the cause of the accident.
(4) When the video input to the low-speed recording means is changed to the video output from the compression means, recording in the high-speed recording area and recording in the low-speed recording area are performed at the same time. Rate video can be recorded simultaneously. Further, since the high speed recording area is not accessed by the low speed recording means, the number of steps can be reduced by one.
(5) If the video input to the low-speed recording means is a video read from the high-speed recording area, the video is temporarily stored in the high-speed recording area, and after this is read out, the video is thinned out. There is no need to compress at multiple locations, and power consumption can be reduced.
(6) Since the compression unit is provided with a function for compressing the video imaged by the imaging apparatus for each frame video, the video can be thinned out by the low-speed recording unit for each predetermined number of frame videos. The time interval between images is constant, and images while the car is moving can be played smoothly.
(7) The event detection device is provided with time information generating means for generating time information and acceleration information detecting means for measuring acceleration, and the time information and acceleration are superimposed and recorded in the high-speed recording area. At the time of reproduction, the image is reproduced with no time lag and the analysis of an accident or the like can be facilitated.
(8) When a plurality of memories are provided in the storage device and a high-speed recording area and a low-speed recording area are formed for each memory, different types of memories can be used according to the characteristics of the area. The performance can be improved and the price can be reduced, and the management of the storage device can be simplified.
(9) If a single memory is provided in the storage device and the capacities of the high-speed recording area and the low-speed recording area are variably set, the recording time can be increased and the number of parts can be reduced by exchanging the memory.

  Hereinafter, a first embodiment of the present invention will be described. FIG. 1 is an explanatory diagram of the event recorder of the present invention.

  As shown in FIG. 1, the event recorder 10 according to the first embodiment of the present invention includes a high-speed camera 11 that is an example of an imaging device that captures images outside the automobile at a high frame rate, and the imaging device. A device that includes a storage device 12 that records captured video, an event detection device 13 that detects accident information, and a recording control means 14 that controls the operation of the event recorder 10 and is attached to an automobile and records accident information. is there.

  The storage device 12 includes a high speed recording area 15 and a low speed recording area 16. The high-speed camera 11 is connected to a compression unit 17 that compresses the captured video, and the compression unit 17 is connected to a high-speed recording unit 18 that records the compressed video endlessly in the high-speed recording area 15 of the storage device 12. ing.

  Further, between the high-speed recording area 15 and the low-speed recording area 16, there is provided low-speed recording means 19 that reads the video recorded in the high-speed recording area 15 and thins it out at a constant rate and records it endlessly in the low-speed recording area 16. It has been.

  The event detection device 13 includes a time data generation circuit 20 that is an example of time information generation means, an acceleration sensor 21 that is an example of acceleration information detection means that measures acceleration applied to the automobile, and a sound volume measurement device (not shown). Has a built-in acoustic microphone 22. The time data generation circuit 20 includes therein a clock generation circuit having a crystal resonator and a frequency reduction circuit. The time information generated from the time data generation circuit 20, the acceleration information generated from the acceleration sensor 21, the audio data generated from the acoustic microphone 22 and the volume information are each digitized and sent to the recording control means 14.

  FIG. 2 is a configuration diagram of the event recorder 10 of the present invention. As shown in FIG. 2, each component of the event recorder 10 is housed integrally in the housing 23. A circuit board 24 is disposed at the front of the housing 23, and the storage device 12 is disposed at the rear. On the circuit board 24, a high-speed camera 11, a time data generation circuit 20, an acceleration sensor 21, and an acoustic microphone 22 are mounted. The recording control means 14 and the low speed recording means 19 are provided as integrated circuits in the CPU 25, and the compression means 17 and the high speed recording means 18 are provided as integrated circuits in the MPU 26. The circuit board 24 is provided with a power supply device 27 for supplying power to the electronic components on the circuit board 24, and the power supply device 27 is provided with a connector 28 for supplying power from the automobile to the power supply device 27. ing. This will be described in detail below.

  The high-speed camera 11 has a wide-angle lens, a CCD element, and an element control circuit, and can capture an image at a high frame rate of 120 frames / second. The high-speed camera 11 takes a video at high speed, automatically digitizes the taken video, and sends the digitized video data to the compression means 17. Note that a plurality of frame buffers that temporarily store captured image data are provided inside the high-speed camera 11.

  As shown in FIGS. 1 and 2, the storage device 12 is connected to the circuit board 24 by wiring 29, and is housed in a protective case 30 having excellent impact resistance and heat resistance in order to prevent damage due to an automobile accident. ing. In addition, the storage device 12 has a memory 31 such as a DRAM having a battery backup function in a removable manner, and the high-speed recording area 15 and the low-speed recording area 16 are formed in the memory 31. .

  The compression means 17 in the MPU 26 employs a RAPIC (Recurrent-ACP-Processed Image Code) method that performs compression for each frame image regardless of adjacent frame images using a compression principle called adaptive orthogonal transform. Yes. The compression means 17 reads the video imaged by the high speed camera 11, temporarily stores it in the internal buffer, and compresses this video image.

  The high speed recording means 18 in the MPU 26 stores the video compressed by the compression means 17 in the high speed recording area 15 of the storage device 12. In the following description, for the sake of convenience, it is assumed that an address indicating a physical position on a storage device is assigned as a logical address in block units corresponding to one frame of a video. After the video is recorded up to the last address in the high-speed recording area 15, it is overwritten from the top address in the high-speed recording area 15. The high-speed recording means 18 receives time information and acceleration information from the recording control means 14, and records the time information and acceleration superimposed on the video.

  FIG. 3 is an explanatory diagram showing the operation of the low-speed recording means of the event recorder. As shown in FIGS. 1 to 3, for example, the low speed recording unit 19 thins out the video in the high speed recording area 15 and records it in the low speed recording area 16 immediately before being overwritten on the high speed recording area 15.

  As shown in FIG. 3 (A), the frame video is sequentially transferred to each address (1, 2,... N,... 2N...) Of the high speed recording area 15 of the memory 31 by the high speed recording means 18. It is recorded. The high speed recording means 18 alternately reads high frame rate videos from a plurality of frame buffers provided in the high speed camera 11 and records them in the high speed recording area 15.

  When the compression ratio by thinning is set to 1 / N, the low speed recording means 19 reads the frame video recorded at the Nth, 2Nth, 3Nth,... Write sequentially from address. The low-speed recording means 19 includes a frame buffer, and the video read from the high-speed recording area 15 is temporarily stored in the frame buffer, and this is sequentially written in the low-speed recording area 16.

After the video has been recorded up to the last address in the high-speed recording area 15, it is overwritten from the top address in the high-speed recording area 15, but the first writing by the low-speed recording means 19 is performed immediately before that. When the first writing by the low-speed recording means 19 is completed, the final write address Y of the low-speed recording area 16 becomes the head address. Thereafter, writing is performed by the high-speed recording means 18, and the high-speed recording area 15 is written up to the Nth address, and this address becomes the final write address X.

  Next, the low speed recording means 19 reads the 2Nth video in the high speed recording area 15 and writes it to the second address in the low speed recording area 16. Thereafter, writing is performed by the high-speed recording means 18, and the high-speed recording area 15 is written up to the 2Nth address. Similarly, the low-speed recording means 19 reads the 3N-th video in the high-speed recording area 15 and writes it to the third address in the low-speed recording area 16, and then the high-speed recording means 18 performs writing. In this way, writing to the high-speed recording area 15 and the low-speed recording area 16 is performed, and the thinned video is continuously recorded in the low-speed recording area 16.

  As shown in FIG. 3B, after the video is recorded up to the last address in the high-speed recording area 15, it is overwritten again from the top address in the high-speed recording area 15.

  As shown in FIG. 3C, when the writing is completed up to the final address of the low-speed recording area 16, the next frame video is recorded over the top address of the low-speed recording area 16.

  As shown in FIG. 3D, when the apparatus is stopped, videos with different frame rates are recorded in the addresses of the high-speed recording area 15 and the low-speed recording area 16 of the memory 31, respectively. . The final write address X in the high-speed recording area 15 and the final write address Y in the low-speed recording area 16 are stored in a non-volatile memory (not shown) by the recording control unit 14.

  When attempting to reproduce the recorded video, first, the final write addresses X and Y are read from the nonvolatile memory, the final write address Y in the low-speed recording area 16 is searched, and the low-speed is started from the address next to the final write address Y. The area 32 up to the end address of the recording area 16 is reproduced first, and then the area 33 from the head address of the low speed recording area 16 to the final write address Y is reproduced. Then, the final write address X in the high speed recording area 15 is searched to reproduce the area 34 from the address next to the final write address X to the end address of the high speed recording area 15, and then from the top address of the high speed recording area 15. The area 35 up to the final write address X is reproduced. By playing in this order, the video up to the occurrence of the accident can be viewed in chronological order. When played back at a normal frame rate, the video recorded in the areas 32 and 33 of the low-speed recording area 16 is played back at a normal speed or in a fast-forward state, and before and after the accident recorded in the areas 34 and 35 of the high-speed recording area 15. Will be played slowly.

  Since each frame video recorded in the low-speed recording area 16 is compressed by the RAPIC method, even when the video is stopped in the middle of playback, it is displayed as an independent image so that it is easy to analyze the cause of the accident. Can be done.

  FIG. 4 is an explanatory diagram showing an installation state of the event recorder. As shown in FIG. 4, the event recorder 10 can be used by being fixed at a plurality of positions of the automobile 36. For example, if it is fixed on the dashboard (position 37) or on the front end of the ceiling (position 38), it becomes easier to capture the front image. Moreover, if it fixes to the ceiling rear end part (position 39) or the rear side of the rear seat (position 40), it becomes easy to capture a rear image. Moreover, if it fixes to the trunk inside (position 41), it will become difficult to damage an apparatus. It is also possible to fix it inside the front bumper (position 42) or inside the rear bumper (position 43). The power source of the event recorder 10 can be obtained by connecting to a socket for cigarette lighter.

Next, the operation of the event recorder 10 will be described with reference to FIGS.
(Preparation for recording)
The recording control means 14 divides the memory 31 of the storage device 12 into a high-speed recording area 15 and a low-speed recording area 16 at a preset ratio, and stores each start address and final address in a nonvolatile memory. deep.

  The high-speed camera 11, the compression means 17, the high-speed recording means 18, and the low-speed recording means 19 are stopped. However, the high-speed camera 11 and the compression means 17 are always operated, and the high-speed recording means 18 and the low-speed recording means. It may be configured to control only 19 on / off. Further, although the time data generation circuit 20, the acceleration sensor 21, and the acoustic microphone 22 are also stopped, they may be always operated.

(Start recording)
The high-speed camera 11, the compression unit 17 and the high-speed recording unit 18 automatically start operation when power is supplied to the apparatus. Repeat at the timing.

  In the high-speed recording process, the video imaged by the high-speed camera 11 is compressed by the compression means 17 and recorded in the high-speed recording area 15 of the storage device 12 by the high-speed recording means 18 in an endless manner. In the low-speed recording process, the video recorded in the high-speed recording area 15 is read by the low-speed recording means 19, thinned out at a constant rate, and recorded endlessly in the low-speed recording area 16 of the storage device 12. The data of the time data generation circuit 20, the acceleration sensor 21, and the acoustic microphone 22 is sent to the high-speed recording means 18, and is recorded together with the video in the high-speed recording area 15. Since audio data has a large capacity, it is compressed and recorded using a compression technique such as MP3.

(Recording stop)
FIG. 5A is an explanatory diagram showing the relationship between the acceleration and time of the event recorder, and FIG. 5B is an explanatory diagram showing the time during which high-speed recording and low-speed recording are performed. The vertical axis in FIG. 5A represents the magnitude of acceleration, the horizontal axis represents time, and the horizontal axis in FIG. 5B represents time. Also, the rectangular frame in FIG. 5B indicates the time during which high-speed recording, reading, and low-speed recording are performed, and the hatched portion indicates data remaining when the apparatus is stopped.
Until the acceleration exceeds a set threshold, high-speed recording and low-speed recording are performed endlessly while overwriting each recording area. Also, video recorded at a high frame rate is rewritten at a low frame rate before being overwritten.

  As shown in FIGS. 1 and 5, when the acceleration exceeds a threshold value, the recording control unit 14 starts a stop process. That is, the recording control unit 14 stops the operations of the high-speed camera 11, the compression unit 17, the high-speed recording unit 18, and the low-speed recording unit 19 after a predetermined time has elapsed after the acceleration exceeds the threshold value. At this time, as shown by the hatched portion at the bottom of FIG. 5, the video before and after the accident is recorded at a high frame rate in the high-speed recording area of the storage device 12, and a long-time video is recorded in the low-speed recording area. Recorded at a low frame rate.

(Regeneration)
After the accident occurs, the event recorder 10 is collected from the automobile, the protective case 30 is opened, and the memory 31 of the storage device 12 is taken out. For reproduction, hardware for expanding video information can be used, or software for expanding video information can be installed in a personal computer and used. Reproduction is performed in the order of the areas 33, 34, and 35 as shown in FIG.

  In the areas 33 and 34, a low frame rate video is recorded for a long time, and in the area 35, a high frame rate video is recorded in detail. Since the video before and after the accident is recorded in detail at a high frame rate, the situation of the accident can be analyzed in detail, and the video before the accident occurs is saved after being converted to a low frame rate, The capacity of the memory 31 is saved.

  Next, an event recorder according to the second embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram of the event recorder according to the second embodiment of this invention. In the event recorder of the second embodiment, the high-speed recording area 46 and the low-speed recording area 48 of the storage device 44 are formed in different memories 45 and 47, respectively, and the MPEG method is used as the compression method of the compression means 49. Although the input to the low-speed recording means 50 is obtained from the compression means 49, since the other configurations are the same, the same components are denoted by the same reference numerals and description thereof is omitted.

  Since the memory 45 constituting the high-speed recording area 46 is recorded at a high frame rate, it is preferable that the writing and reading speed be fast. For example, a DRAM having a battery backup function can be used. On the other hand, since the memory 47 constituting the low-speed recording area 48 records by thinning out the frame video, it can be used even if the writing speed is low.

  In the MPEG system, each frame video is converted into one of an I picture, a B picture, and a P picture by a compression method. An I picture is a frame video obtained by directly encoding a video signal without using motion prediction, and all the image information of one picture is held by itself. A B picture is a frame image encoded using motion prediction from both past and future images, and a P picture is an image encoded using prediction only from motion from the past direction. . In the MPEG system, a plurality of frame images are managed as one group, and one group includes one or more I pictures.

  The low-speed recording unit 50 receives the video output from the compression unit 49 and thins out one group of frame videos to form one frame video. At this time, since the B picture and the P picture cannot be reproduced unless they are combined with the I picture, the low speed recording means is configured to select the I picture and leave it as one frame video. Note that the video input from the compression unit 49 is performed simultaneously with the high-speed recording unit 18, and recording in the high-speed recording area 45 and recording in the low-speed recording area 47 are performed in parallel. Similarly to the event recorder 10 of the first embodiment shown in FIG. 1, the high-speed recording means 18 and the low-speed recording means 50 receive the time information and acceleration information from the recording control means 14 and time with the thinned video. Information and acceleration are superimposed and recorded.

  FIG. 7 is an explanatory diagram showing the operation of the low-speed recording means of the event recorder of the second embodiment. As shown in FIG. 7, the storage device 44 forms a high-speed recording area 46 in a memory 45 having a high writing speed and a high reading speed, and forms a low-speed recording area 48 in a memory 47 having a low writing speed.

  As shown in FIG. 7A, the high-speed recording means 18 converts each frame image of the video input from the compression means 49 to each address (1, 2,... N,. 2N...) In order. The frame image forms one group for every N frames.

On the other hand, the low-speed recording means 50 expands the video input from the compression means 49 on the buffer, searches for the I picture from the top address of the first group, reads only _one I picture (I ₁ ), Write to the start address of the low-speed recording area 48. Next, an I picture is searched from the top address of the second group, and only one I picture (I ₂ ) is read and written to the second address of the low speed recording area 48.

  As shown in FIG. 7B, when the writing is completed up to the final address of the low-speed recording area 48, the next frame image is recorded by overwriting the head address of the low-speed recording area 48. Similarly, in the high speed recording area 46, when the writing to the final address is completed, the next frame image is recorded at the head of the high speed recording area 46.

  As shown in FIG. 7C, when the video is recorded up to the final write address X in the high-speed recording area 46 and the apparatus is stopped before the video is compressed, the low-speed recording in the high-speed recording area 46 of the memory 45 and the memory 47 is performed. Video is recorded at each address in the area 48. The final write addresses X and Y of the high speed recording area 46 and the low speed recording area 48 at this time are stored in a separately provided nonvolatile memory.

  FIG. 8 shows the time during which high-speed recording and low-speed recording are performed. The rectangular frame in the figure indicates the time during which high-speed recording and low-speed recording are performed, and the hatched portion indicates data remaining when the apparatus is stopped. As shown in FIG. 8, recording in the high-speed recording area 46 and recording in the low-speed recording area 48 are continuously performed while being overwritten.

  Since recording in the high-speed recording area 46 and recording in the low-speed recording area 48 are performed at the same time, the video at the time of event occurrence is recorded in each. Therefore, when the recorded video is to be reproduced, the reproduction of the low-speed recording area 48 and the reproduction of the high-speed recording area 46 can be performed separately. When the low-speed recording area 48 and the high-speed recording area 46 are played back in this order, the video up to the event occurrence is played back at a normal speed, and then the video before and after the event is played back again in slow motion. Since only the I picture is recorded in the low-speed recording area 48, there is little deterioration in image quality even if the frame video is thinned out.

  The event recording method and the event recorder of the present invention can be used for, for example, recording display in sports, monitoring of an accident in a building or a store, etc. in addition to the recording of an automobile accident.

Explanatory drawing of the event recorder of the 1st Embodiment of this invention Configuration diagram of the event recorder Explanatory drawing which shows the effect | action of the low-speed recording means of the event recorder Explanatory drawing showing the installation state of the event recorder (A) is explanatory drawing which shows the relationship between the acceleration of the event recorder, and time, (B) is explanatory drawing which shows the time which performs high speed recording and low speed recording Explanatory drawing of the event recorder of the 2nd Embodiment of this invention Explanatory drawing which shows the effect | action of the low-speed recording means of the event recorder Explanatory diagram showing time for high-speed recording and low-speed recording of the event recorder

Explanation of symbols

10 Event recorder 11 High-speed camera (imaging device)
12 storage device 13 event detection device 14 recording control means 15 high speed recording area 16 low speed recording area 17 compression means 18 high speed recording means 19 low speed recording means 20 time data generating circuit (time information generating means)
21 Acceleration sensor (acceleration information detection means)
22 acoustic microphone 23 housing 24 circuit board 25 CPU
26 MPU
27 Power supply device 28 Connector 29 Wiring 30 Protective case 31 Memory 32 to 35 Region 36 Motor vehicle 37 to 43 Position 44 Storage device 45 Memory 46 High speed recording region 47 Memory 48 Low speed recording region 49 Compression means 50 Low speed recording means

Claims (9)

An imaging device that captures video, a storage device that records video captured by the imaging device, an event detection device that detects an event, and recording to the storage device is stopped based on information from the event detection device In an event recording method comprising a recording control means having a function, and recording video up to immediately after the event occurs,
The video imaged by the imaging means is compressed, the compressed information is recorded endlessly in the high-speed recording area of the storage device, and the information read from the oldest part of the information recorded in the high-speed recording area is read at a certain rate. An event recording method characterized by thinning out and recording endlessly in a low-speed storage area of the storage device. An imaging device that captures video, a storage device that records video captured by the imaging device, an event detection device that detects an event, and recording to the storage device is stopped based on information from the event detection device In an event recording method comprising a recording control means having a function, and recording video up to immediately after the event occurs,
The video captured by the imaging means is compressed, the compressed video is recorded endlessly in the high-speed recording area of the storage device, and the compressed video is thinned out at a constant rate to endlessly in the low-speed storage area of the storage device. An event recording method characterized by recording in the above. An imaging device that captures video, a storage device that records video captured by the imaging device, an event detection device that detects an event, and a video recording to the storage device based on information from the event detection device In an event recorder comprising a recording control means having a function of stopping
The storage device includes a high-speed recording area and a low-speed recording area,
Between the imaging device and the storage device, compression means for compressing the video imaged by the imaging device;
High-speed recording means for recording the information compressed by the compression means endlessly in a high-speed recording area of the storage device;
An event recorder, comprising: a low-speed recording means for thinning compressed video at a constant rate and recording it endlessly in a low-speed recording area of the storage device. 4. The event recorder according to claim 3, wherein the video input to the low-speed recording unit is a video output from the compression unit. 4. The event recorder according to claim 3, wherein the video input to the low-speed recording means is a video read from the high-speed recording area. 6. The event recorder according to claim 3, wherein the compression unit has a function of compressing a video image captured by the imaging apparatus for each frame video image. The event detection apparatus includes time information generation means for generating time information and acceleration information detection means for measuring acceleration, and the high-speed recording area records time information and acceleration together with video. The event recorder according to any one of claims 3 to 6, characterized in that: The storage device according to any one of claims 3 to 7, wherein the storage device includes a plurality of memories, and the high-speed recording area and the low-speed recording area are formed for each of the memories. The event recorder described. The event according to any one of claims 3 to 8, wherein the storage device includes a single memory, and the capacities of the high-speed recording area and the low-speed recording area are variably set. Recorder.

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