Synchronized camera system consisting of multiple high-speed cameras

Abstract

Synchronizing image frames from multiple conventional high-speed cameras has been difficult. [Solution] The synchronized camera device of the present invention, which is made up of multiple high-speed cameras, comprises multiple high-speed cameras, an imager unit which captures target images in sequence at a set exposure timing, a recording memory, a recording unit which records a specific image captured by the imager unit as an image frame of digital data in the recording memory upon input of a trigger signal, a system control unit which has a timer and performs various calculations, and a synchronization signal setting means which sets a synchronization signal in each of the high-speed cameras and transmits the set synchronization signal to each of the high-speed cameras. The synchronization signal is a trigger time. The synchronization signal is also a sequence number match time and a trigger sequence number.

Description

[Technical field]

[0001] The present invention relates to a synchronized camera device that is made up of a plurality of digital high-speed cameras for synchronously photographing a plurality of high-speed cameras. [Background technology]

[0002] (Explanation of the configuration of a typical digital high-speed camera)

[0003] Fig. 22 shows the configuration of a typical digital high-speed camera. The digital high-speed camera 1 is made up of a camera body 2 and a photographic lens 3. Some cameras do not have the photographic lens 3 and use other optical systems.

[0004] The camera body 2 includes an imager unit 4 consisting of an image sensor or the like which captures a target image by sequentially exposing at a set exposure timing (cycle); a recording memory 5 consisting of a DRAM or the like which is formed to record, for example, in a ring buffer shape; a recording unit 6 which sequentially records the images captured by the imager unit 4 in the recording memory 5 as image frames of digital data, and which stops recording in the recording memory 5 and stops overwriting when a predetermined number of image frames have been recorded upon input of a trigger signal which will be described later, thereby leaving the images of the predetermined image frames in the recording memory 5; a system control unit 7 which performs or causes various calculations and storage, and which has a timer which manages the time, a CPU, and a ROM which includes RAM and software related to the operation thereof; an image processing unit 8 consisting of a DSP, a GPU, or the like; an input / output unit 9 for inputting and outputting external signals; and a power supply unit 10 for supplying power to the camera body 2.

[0005] 22, the imager unit 4, recording unit 6, image processing unit 8, input / output unit 9, power supply unit 10, etc. are shown as separate entities from the system control unit 7. However, some or all of the imager unit 4, recording unit 6, image processing unit 8, input / output unit 9, power supply unit 10, etc. may form part of the system control unit 7.

[0006] (Description of how the recording unit 6 records in the recording memory 5)

[0007] In the conventional digital high-speed camera in which recording is performed in memory, the ring buffer-like recording memory 5 is configured such that image frames are written in sequence from the beginning of the storage area, and when the entire area is written, the storage area is immediately overwritten with new image frames from the beginning, and this overwriting is repeated until recording is stopped.

[0008] Then, for example, the recording unit 6 sequentially exposes the captured images at a preset exposure timing (period) in the recording memory 5 in a ring buffer-like manner, and writes the images into digital data, thereby recording image frames at the above-mentioned period sequentially.

[0009] The recording unit 6 is provided with a recording image frame number setting unit which, upon input of a trigger signal, stops recording and stops overwriting, thereby setting in advance the number of image frames to be left in the recording memory 5.

[0010] Then, the recording unit 6 writes a preset number of images from the time when a trigger signal is input to the recording unit 6, and then stops writing and stops overwriting the recording memory 5. This is configured so that a required number of image frames are recorded before and after the trigger input.

[0011] For example, as shown in FIG. 23, there is a general high-speed shooting function (hereinafter, normal recording) that records a preset number of images (e.g., 100 frames before the trigger and 100 frames after the trigger (in this example, after the trigger, including the trigger frame at the time of trigger input)) written before and after the input of the trigger signal as consecutive image frames in the recording memory 5.

[0012] In the expressions "pre-trigger" and "post-trigger," the trigger frame may be included in either, or the trigger frame may not be included in either and the pre-trigger and post-trigger states may be based on the trigger frame.

[0013] In addition, the recorded image frame number setting section may set the predetermined number before or after the trigger signal is input to 0, excluding the trigger frame.

[0014] (CPU trigger signal description)

[0015] Then, the TRIG IN connector of the input / output unit 9 of the camera 1 is directly connected to an electrical signal input unit of a trigger generator that generates a trigger signal by an electrical signal input unit with a proper input method (signal polarity, etc.) and negligible electrical signal delay, via an electrical signal cable, without the intervention of an asynchronous electronic device. The trigger signal generated by the trigger generator is then input to the recording unit 6 via the electrical signal cable. However, it is also possible to input a trigger generated by a system control unit 7 inside the high-speed camera (hereinafter referred to as a "CPU trigger") to the recording unit 6.

[0016] The electric signal cable may be, for example, a BNC (Bayonet Neill Concelman) cable or a coaxial cable.

[0017] According to the CPU trigger method, the camera and the electronic device for communication of the trigger generator are connected by a communication format such as TCP / IP (including UDP; the same applies below) protocol by wireless LAN (Wi-Fi) or wired LAN (Ethernet), etc. Then, the high-speed camera that receives a trigger signal from the trigger generator generates the CPU trigger and inputs the generated CPU trigger to the recording unit 6, and this is used as a simple trigger signal input method.

[0018] The communication electronic device of the trigger generator may be, for example, a trigger generator that generates a trigger signal from an electrical signal input section in which the input method (signal polarity, etc.) such as contact input (contact switch) or isolated input (current loop using a photocoupler) is appropriate and the delay in the electrical signal is negligible, or a trigger generator that generates a trigger signal from a control device such as a remote control device.

[0019] (Explanation of synchronous shooting with each camera)

[0020] Furthermore, when taking synchronous images using multiple digital high-speed cameras, it is first necessary to accurately align the time axes of each camera. To achieve this, for example, it is necessary to avoid the presence of asynchronous electronic devices between the cameras as much as possible. To this end, it is necessary to connect the cameras with electrical signal cables such as BNC cables and coaxial cables so that asynchronous electronic devices are not interposed in the communication means.

[0021] That is, the cameras are connected by the electric signal cables so that no asynchronous electronic devices for communication are interposed between them. For example, no asynchronous electronic devices for conversion to a communication format based on TCP / IP (including UDP) protocols are interposed between the cameras. This reduces the transmission delay caused by the interposition of multiple asynchronous electronic devices, and makes it possible to align the time axes of the cameras.

[0022] Then, by having each camera expose at a predetermined exposure timing (period) in accordance with the above-mentioned time axis, the image frames of each camera are synchronized. Then, by making the image frames (hereinafter referred to as trigger frames) in which the trigger signals of each high-speed camera are input the same, it becomes possible for each camera to take a synchronous image.

[0023] Note that synchronizing the image frames of the cameras may mean, for example, exposing at the specified exposure timing in accordance with the synchronized time axes of the cameras, and then setting the boundaries of the image frames (i.e., the start time or end time of the image frames) based on the exposure start time or exposure end time of this exposure, and then matching the boundaries of each image frame (i.e., the start time or end time of the image frames).

[0024] As a method of making the trigger frames the same, for example, as shown in Fig. 24, it is determined whether or not a trigger signal has been generated at the end time of each image frame in which the image frames of each high-speed camera are synchronized. Then, when the trigger signal is detected, the image frame is determined to be the trigger frame when the trigger signal was generated. This makes it possible to match the trigger frames of each camera, enabling simultaneous shooting with multiple cameras.

[0025] For example, Patent Document 1 discloses a general high-speed video camera. [Prior art documents] [Patent documents]

[0026] [Patent Document 1] Patent No. 4657379 Summary of the Invention [Problem to be solved by the invention]

[0027] (Explanation of why it is difficult to input trigger signals to the recording unit 6 simultaneously)

[0028] To use the CPU trigger to capture images synchronously with multiple digital high-speed cameras, it is necessary to simultaneously input a CPU trigger to the recording unit 6 of each camera 1. However, since the system control unit 7 including the CPU is not synchronized with the image frames of the cameras, it is not possible to guarantee that the CPU trigger will be input to the recording unit 6 of each camera at the same time. As a result, it is not possible to match the trigger frames of each camera.

[0029] In order to match the trigger frames of multiple cameras, it is necessary to input a trigger signal from outside to each camera at the same time. However, if the connection between each camera and the trigger generator is made using a communication format based on the TCP / IP protocol over a wireless LAN (Wi-Fi) or wired LAN (Ethernet), there is no guarantee that the recording unit 6 of each camera will receive the signal at the same time.

[0030] In addition, in the above case, multiple asynchronous electronic devices are interposed between the camera and the trigger generator in order to convert the communication format into one using protocols such as TCP / IP (including UDP). This means that delays cannot be ignored, making it difficult to synchronize the cameras.

[0031] (Explanation of how to input trigger signals to the recording unit 6 simultaneously)

[0032] For this reason, in order to enable each camera to receive a signal simultaneously, electrical signal cables such as BNC cables or coaxial cables must be wired between each camera and the trigger generator with as little intervening electronic devices as possible for converting the communication format into one based on the TCP / IP protocol for communication.

[0033] Furthermore, as described above, in order to synchronize the time axes of a plurality of cameras, it is necessary to connect the cameras with a synchronization signal, and therefore it is also necessary to lay an electrical signal cable for time axis synchronization.

[0034] (Explanation of the disadvantages of connecting with a cable)

[0035] 25, for example, it is necessary to connect each camera 1 to a trigger generator 11 that generates a trigger signal from the electrical signal input unit with an electrical signal cable 12 for the trigger signal, and also to connect each camera 1 to a time signal transmitter 13 with an electrical signal cable 14 for the time synchronization signal. This makes the cabling complicated.

[0036] In addition, if physical wiring such as cables is used to connect cameras to each other or to connect a camera to a synchronization system, the installation location and movement range of the cameras are limited, narrowing the range of possible applications.

[0037] The present invention is intended to eliminate the above-mentioned drawbacks. [Means for solving the problem]

[0038] The synchronized camera device of the present invention, which is made up of a plurality of high-speed cameras, comprises an imager section which sequentially exposes the cameras at a set exposure timing to capture a target image, a recording memory, a recording section which, upon input of a trigger signal, records a predetermined image captured by the imager section as an image frame of digital data in the recording memory, a plurality of high-speed cameras each having a timer and a system control section which performs various calculations, and a synchronization signal setting means which sets a synchronization signal and transmits the set synchronization signal to each of the high-speed cameras, the system control section having a camera synchronization means, the camera synchronization means synchronizing the timer based on a current time signal sent from an external device at regular intervals, generating a current time, and determining the exposure timing based on the current time, a synchronization signal receiving means which receives a synchronization signal from the synchronization signal setting means, and a synchronization signal received by the synchronization signal receiving means. When it is determined that the current time acquired from the current time generating means has reached the current time, the synchronization signal is input to the image frame at that time. and a frame associating means for associating the frames.

[0039] Further, the synchronization signal setting means for setting the synchronization signal and transmitting the set synchronization signal to each of the high-speed cameras is a trigger time setting means for setting a time for sending a trigger signal to the recording unit of each of the high-speed cameras and transmitting the set trigger time to each of the high-speed cameras, the camera synchronization means is a trigger frame synchronization means, the synchronization signal receiving means for receiving the synchronization signal from the synchronization signal setting means is a trigger time receiving means for receiving the trigger time from the trigger time setting means, and the synchronization signal received by the synchronization signal receiving means is a trigger frame synchronization means for receiving the synchronization signal from the high-speed cameras. When it is determined that the current time acquired from the current time generating means has reached the current time, the synchronization signal is input to the image frame at that time. The frame associating means associates the trigger time received by the trigger time receiving means. When it is determined that the current time acquired from the current time generating means has reached the trigger time, the trigger time is added to the image frame at that time. Associate Frame Association It is characterized in that it is a means.

[0040] The frame association means is also characterized in that it is a means for determining whether the current time of the image frame has reached the trigger time obtained from the trigger time receiving means, and if it is determined that the current time of the image frame has reached the trigger time, sets the image frame as the image frame at the trigger time, transmits a trigger signal to the recording unit, and sets a predetermined image frame based on the image frame, and synchronizes each high-speed camera by aligning this predetermined image frame in each high-speed camera.

[0041] In addition, synchronizing each high-speed camera by matching a predetermined image frame based on the above image frame in each high-speed camera is characterized by matching the image frame at the trigger time of each camera as a predetermined image frame.

[0042] In addition, synchronizing each high-speed camera by matching a predetermined image frame based on the image frame in each high-speed camera is characterized by providing an image frame setting unit in the frame association means of each camera, which sets an image frame having a predetermined relationship from the image frame at the trigger time of each camera, and matching the predetermined image frames set by the image frame setting unit.

[0043] The predetermined image frame is an event frame of the image frame when a trigger signal is input to each of the cameras.

[0044] The trigger time is set to a time prior to the time when the trigger time setting means receives the trigger signal.

[0045] The trigger time is set to the time of the image frame when recording is to be ended.

[0046] The trigger time is set to the time of the image frame when recording is terminated, and an image frame setting unit provided in the frame association means of each of the high-speed cameras calculates an event frame, which is the image frame when the trigger signal is input, from the image frame at the trigger time, and synchronizes each of the high-speed cameras by matching these event frames.

[0047] Also, the trigger times input to the cameras are the same.

[0048] The trigger time of each camera is set corresponding to the exposure timing set for each camera and / or the number of image frames to be recorded and retained in the recording memory.

[0049] The trigger time is set to be later than the start time and earlier than the end time of each of the image frames for which the trigger time of each of the cameras is set.

[0050] In addition, in the case of cameras in which the recording speed set for each camera is different and the start times of the image frames are aligned to synchronize the image frames of each camera, the trigger time is set to be a time obtained by adding a time greater than 0 and shorter than the period (1 / recording speed) of the camera with the fastest recording speed to the start time of the image frame of the camera with the slowest recording speed.

[0051] In addition, in the case of cameras in which the recording speed set for each camera is different and the end times of the image frames are aligned to synchronize the image frames of each camera, the trigger time is set to be the end time of the image frame of the camera with the slowest image speed minus a time that is greater than 0 and shorter than the period (1 / recording speed) of the camera with the fastest recording speed.

[0052] The current time signal is obtained from a wireless time synchronization device that is connected to each of the high-speed cameras by an electric signal cable without the need for an electronic device and that is configured to wirelessly synchronize with each other.

[0053] The trigger time receiving means is characterized in that it receives the trigger time through communication means in a communication format based on the TCP / IP protocol.

[0054] The communication means using the TCP / IP protocol communication format is characterized by being data communication using the Wi-Fi standard.

[0055] The communication means in the communication format according to the TCP / IP protocol is characterized by data communication according to the Ethernet standard.

[0056] The present invention is also characterized in that it further comprises a means for transmitting the trigger time accepted by the trigger time accepting means of at least one of the plurality of high-speed cameras to a device that transmits the trigger time to the trigger time accepting means of the other high-speed cameras.

[0057] The present invention is also characterized in that it further comprises a means for transmitting the trigger time accepted by the trigger time accepting means of at least one of the plurality of high-speed cameras to the trigger time accepting means of the other high-speed cameras via wired or wireless communication.

[0058] The trigger time setting means is provided in a device separate from each of the high-speed cameras, and the trigger time generated by the trigger time setting means is transmitted to each of the high-speed cameras via wired or wireless communication.

[0059] The trigger time setting means is provided in at least one of the plurality of high-speed cameras, and notifies the trigger time generated by the trigger time setting means to the trigger time receiving means of the at least one high-speed camera and transmits the trigger time to the trigger time receiving means of the other high-speed cameras.

[0060] The trigger time generated by the trigger time setting means is generated based on a trigger signal input to the at least one high-speed camera.

[0061] The trigger signal is generated by a trigger generator, and the generated signal is transmitted to the trigger time setting means by a communication means in a communication format according to the TCP / IP protocol provided in the trigger generator.

[0062] The trigger signal is generated by an electrical signal input unit of a trigger generator, and the generated signal is transmitted from the electrical signal input unit to the trigger time setting means via an electrical signal cable without the intervention of an electronic device.

[0063] The system control unit has a sequence number setting unit which sequentially numbers the image frames recorded in the recording memory at a set predetermined exposure timing, and the synchronization signal setting means which sets the synchronization signal and transmits the set synchronization signal to each of the high-speed cameras comprises a sequence number match time setting means which sets (generates) a sequence number match time at which the sequence numbers of each of the high-speed cameras are set to a predetermined number and transmits the set synchronization signal to each of the high-speed cameras, and a trigger sequence number transmitting means which generates and transmits a trigger sequence number corresponding to an image frame to which a trigger signal should be transmitted, and the camera synchronization means is a sequence number synchronization means, and the synchronization signal receiving means which receives the synchronization signal from the synchronization signal setting means comprises a sequence number match time receiving means which receives the sequence number match time from the sequence number match time setting means and a trigger sequence number receiving means which receives the trigger sequence number from the trigger sequence number transmitting means, and the synchronization signal received by the synchronization signal receiving means When it is determined that the current time acquired from the current time generating means has reached the current time, the synchronization signal is input to the image frame at that time. The frame associating means is the above The sequence number match time received by the sequence number match time receiving means When it is determined that the current time generated by the current time generating means has reached, the sequence number of each high-speed camera is set to a predetermined value by a sequence number matching unit to match the sequence numbers of each high-speed camera, and the sequence numbers of each high-speed camera are The trigger sequence number received by the trigger sequence number receiving means When it is determined that the image frame has reached the threshold, the trigger sequence number is added to the image frame. and a frame associating means for associating the frames.

[0064] The frame association means is further characterized in that it is a means for determining whether the current time generated by the current time generating means has reached the sequence number match time obtained from the sequence number match time receiving means, and if it is determined that the current time has reached the sequence number match time, sets the sequence number of each high-speed camera to a predetermined value by a sequence number matching unit to match the sequence numbers of each high-speed camera, and when the sequence number of each high-speed camera reaches the trigger sequence number received by the trigger sequence number receiving means, sets the image frame at that time as the image frame for the trigger sequence number, transmits a trigger signal to the recording unit, and synchronizes each camera by matching the image frame for this trigger sequence number.

[0065] In addition, when the exposure timings of the cameras are different, each camera is provided with a sequence number correction section for correcting the sequence numbers so that the sequence numbers are the same at the same time. Effect of the Invention

[0066] According to the present invention, even if the input timing of external signals to each camera is different, it is possible to align the trigger frames of each camera by inputting the same trigger time information, sequence number match time, etc. This eliminates the need for cabling for trigger signals, etc. to each camera.

[0067] In addition, by using it in conjunction with a conventional general-purpose wireless time synchronization device to wirelessly synchronize the time of multiple cameras, the combination of a wireless time synchronization device with a CPU trigger based on time information can eliminate all physical wiring, such as connecting multiple cameras together or between the cameras and the synchronization system, and make it possible to move cameras freely. [Brief description of the drawings]

[0068] [Figure 1] FIG. 1 is an explanatory diagram of a configuration of a synchronized camera device comprising a plurality of high-speed cameras according to the present invention. [Diagram 2]FIG. 1 is an explanatory diagram showing high-speed photography with equal division using a phase-locked loop circuit that generates a 1 Hz signal from the time signal of the present invention. [Diagram 3] FIG. 1 is a diagram for explaining the configuration of a high-speed camera according to the present invention. [Figure 4] FIG. 2 is an explanatory diagram of time synchronization of the high-speed camera of the present invention. [Diagram 5] FIG. 4 is an explanatory diagram of a method for connecting a trigger time setting means of the high-speed camera of the present invention. [Figure 6] 13 is an explanatory diagram of another connection method of the trigger time setting means of the high-speed camera of the present invention. FIG. [Figure 7] FIG. 13 is an explanatory diagram of still another connection method of the trigger time setting means of the high-speed camera of the present invention. [Figure 8] FIG. 13 is an explanatory diagram of still another connection method of the trigger time setting means of the high-speed camera of the present invention. [Figure 9] FIG. 4 is an explanatory diagram of a method for setting a trigger time according to the present invention. [Figure 10] FIG. 2 is an explanatory diagram of a first method for setting a trigger time according to the present invention. [Figure 11] FIG. 11 is an explanatory diagram of a second method for setting a trigger time according to the present invention. [Figure 12] FIG. 11 is another explanatory diagram of the second trigger time setting method of the present invention. [Figure 13] FIG. 11 is an explanatory diagram of a third method for setting a trigger time according to the present invention. [Figure 14] FIG. 11 is an explanatory diagram of another example of the trigger time setting method 3 of the present invention. [Figure 15] FIG. 11 is an explanatory diagram of another example of a method for setting a trigger time according to the present invention. [Figure 16] FIG. 11 is an explanatory diagram of yet another example of a method for setting a trigger time according to the present invention. [Figure 17] FIG. 1 is a diagram showing a comparison of flows between a conventional method and a new method according to the present invention. [Figure 18] FIG. 11 is an explanatory diagram of a method for synchronizing using sequence numbers according to a second embodiment of the present invention. [Figure 19] FIG. 11 is an explanatory diagram of a method for synchronizing using sequence numbers according to a second embodiment of the present invention. [Figure 20]FIG. 11 is an explanatory diagram of a method for synchronizing using sequence numbers according to a second embodiment of the present invention. [Figure 21] FIG. 11 is an explanatory diagram of a method for synchronizing using sequence numbers according to a second embodiment of the present invention. [Figure 22] FIG. 1 is an explanatory diagram of a conventional high-speed camera. [Figure 23] This is an explanatory diagram in which, upon trigger input, 100 frames before the trigger and 100 frames after the trigger (including the trigger frame) are recorded. [Figure 24] FIG. 13 is an explanatory diagram showing how image frames are aligned in response to a trigger input, with frames from cameras 1 and 2 synchronized. [Diagram 25] FIG. 1 is an explanatory diagram of a conventional high-speed camera. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] Hereinafter, preferred embodiments of the high-speed camera of the present invention will be described with reference to the drawings. Note that the high-speed camera of the present invention is not limited to the following description, and can be modified as appropriate without departing from the spirit of the present invention.

[0070] Furthermore, the meaning of "simultaneous" and "synchronized" used below does not mean strict simultaneous or synchronized, but is a concept that includes a range of error that does not interfere with synchronizing image frames, which is consistent with the spirit of the present invention.

[0071] The same parts as those described in the above conventional example are given the same reference numerals and the description thereof will be omitted. EXAMPLES

[0072] FIG. 1 shows the configuration of a high-speed camera according to an embodiment of the present invention.

[0073] (Explanation of the Overall Configuration of the Present Invention)

[0074] As shown in FIG. 1, the high-speed camera of the present invention has a camera synchronization means in the system control unit 7 of each of the conventional high-speed cameras, and also has a synchronization signal setting means in a separate device such as a tablet different from each of the cameras 1, or in one camera 1 (parent camera 1a), which sets (generates) a synchronization signal and transmits it to each required high-speed camera 1.

[0075] It should be noted that a plurality of cameras 1 (parent cameras 1a) may be provided.

[0076] In the first embodiment of the present invention, the camera synchronization means is composed of a trigger frame synchronization means 15, and the synchronization signal setting means which sets (generates) the synchronization signal and transmits it to each required high-speed camera 1 is composed of a trigger time setting means 16 which sets (generates) a trigger time for sending a trigger signal to each high-speed camera and transmits it to each required high-speed camera 1.

[0077] That is, in the first embodiment of the present invention, first, the current time of the timer of each camera is synchronized, the time axis of each camera is aligned, and then the image frames of each camera are synchronized by exposing at a predetermined exposure timing (period) aligned with the time axis.Then, the trigger time setting means 16 transmits the same trigger time to each high-speed camera, and when each high-speed camera reaches the trigger time, it transmits a trigger signal to the recording unit of each high-speed camera, and the predetermined image frames of each camera are aligned, thereby synchronizing each camera.

[0078] The trigger frame synchronization means 15 synchronizes the timer of the system control unit 7 with a high-precision current time signal (time code) sent at regular, low-resolution timing from an external device other than each high-speed camera, such as a time signal transmitting device 13, and further comprises current time generation means 17 which divides a predetermined time into equal intervals based on the current time signal to generate a high-resolution current time, exposure signal generation means 18 which generates an exposure signal for capturing an image according to the exposure timing (period) set by the current time generation means 17 based on the current time divided into equal intervals, trigger time acceptance means 19 which accepts the trigger time, and frame association means 20 which associates the synchronization signal of the trigger time received by the trigger time acceptance means 19 with a predetermined image frame captured and recorded by exposure by the exposure signal generation means 18.

[0079] The frame association means 20 judges whether the current time generated by the current time generation means 17 has reached the trigger time obtained from the trigger time reception means 19, and if it judges that the current time has reached the trigger time, sets the image frame at that time as the image frame at the trigger time, transmits a trigger signal to the recording unit 6, and also sets a specified image frame based on the image frame at the trigger time, and synchronizes each camera 1 by matching this specified image frame in each camera.

[0080] Note that the predetermined image frame based on the image frame at the trigger time may be, for example, the image frame at the trigger time of each camera 1, and the cameras 1 may be synchronized by matching the image frames. The image frame at the trigger time may be, for example, an image frame at a time slightly ahead of the current time when the trigger signal is received, or an image frame at the final recording time when recording is terminated.

[0081] Furthermore, as a specified image frame based on the image frame at the trigger time, for example, an image frame setting unit may be provided in the frame association means 20 of each camera 1, which sets an image frame having a specified relationship from the image frame at the set trigger time (for example, if the image frame at the trigger time is the image frame at the time of the final recording, it is the event frame when the trigger signal is input), and this set specified image frame (for example, in the above example, the event frame) may be set, and each camera 1 may be synchronized by matching each of these image frames.

[0082] (Explanation of the current time generating means 17)

[0083] 3, for example, a time signal transmitting device 13 that transmits a time signal (time code) and each of the cameras 1 are connected by an electric signal cable 14 such as a BNC or coaxial cable so as to minimize the need for electronic devices in the communication means in order to reduce transmission delays. The system control unit 7 of each of the cameras 1 periodically receives a low-resolution but highly accurate time signal from the time signal transmitting device 13 via the electric signal cable 14.

[0084] For example, the camera 1 (parent camera 1a) and the time signal transmitting device 13 may be connected by the electrical signal cable 14 without the need for an electronic device, and the electrical signal cable 14 may be distributed by a signal distributor and connected to each of the other cameras 1 (child cameras 1b).

[0085] Then, each of the cameras 1 is synchronized with the time signal, and the current time is generated by the current time generating means 17, so that each of the cameras 1 is synchronized with the current time.

[0086] The current time generating means 17 also sets the timing interval (e.g., 1 second) at which the time signal is periodically received. Then, as shown in Fig. 2, the current time generating means 17 divides the timing interval (e.g., 1 second) equally (e.g., 1000 equal parts) using a phase locked loop (PLL) or the like provided therein. This makes it possible to generate a highly accurate time with high resolution.

[0087] Common time code standards for synchronizing multiple devices include IRIG-B and LTC. Although these time codes do not have frame rates that meet the needs of high-speed photography, they tend to have small phase shifts, meaning that the synchronization accuracy between devices tends to be high.

[0088] Further, in addition to directly connecting each camera 1 and the time signal transmitting device 13 with the electric signal cable 14 as shown in Fig. 3, for example, as shown in Fig. 4, in order to reduce transmission delay in the communication means, and to avoid the use of electronic devices as much as possible, a wireless time synchronization device 21 is connected to each camera 1 with an electric signal cable 21a represented by a BNC or coaxial cable. Then, each of the wireless time synchronization devices 21 is synchronized with each other wirelessly. Then, each of the wireless time synchronization devices 21 wirelessly synchronized with each other may transmit a time signal (time code) to the corresponding camera 1, thereby synchronizing each of the cameras 1.

[0089] (Explanation of exposure signal generating means 18)

[0090] Next, the exposure signal generating means 18 generates an exposure signal based on the current time at equal intervals (for example, 1 millisecond intervals), and images are captured sequentially using this exposure signal, thereby achieving high-speed photography.

[0091] The timing (period) of the exposure signal is set to a predetermined time. For example, when one second is divided into 1000 equal parts, it becomes an interval of 1 millisecond, and the exposure signal is generated at the interval of 1 millisecond, the imager unit 4 exposes, captures an image, and generates each image frame of the period. The exposure time is set to a time that can be regarded as the same as the period, or may be set to be shorter than the period.

[0092] Then, each camera exposes at a predetermined exposure timing (period) in accordance with the current time, so that the image frames of each camera are synchronized. Note that synchronizing the image frames of the cameras may mean, for example, exposing at the specified exposure timing in accordance with the synchronized time axes of the cameras, and then setting the boundaries of the image frames (i.e., the start time or end time of the image frames) based on the exposure start time or exposure end time of this exposure, and then matching the boundaries of each image frame (i.e., the start time or end time of the image frames).

[0093] (Explanation of trigger time reception means 19)

[0094] Next, for example, as shown in Figures 1 and 3, the trigger time generated by the trigger time setting means 16 described later is transmitted (A) from a trigger time transmitting means such as a communication format based on the TCP / IP protocol, for example, wirelessly, and is received (A) by the trigger time receiving means 19 of each camera 1.

[0095] In the figure, A indicates communication at the trigger time.

[0096] FIG. 3 shows an example in which the trigger time setting means 16 is provided in a device 22 such as a separate tablet, which is different from each camera 1.

[0097] In this example, the device 22 that receives a trigger signal from the trigger generator generates the trigger time using the trigger time setting means 16, and this generated time signal is transmitted (A) to each camera 1 and received (A) by the trigger time receiving means 19 of each camera 1.

[0098] 5 shows another method for transmitting the trigger time to each camera, in which the time synchronization means is omitted.

[0099] As shown in FIG. 5, the system control unit 7 of one camera 1 (parent camera 1a) has the trigger time setting means 16. In this example, as shown in FIG.

[0100] In this example, for example, a trigger generator 23 which generates a trigger signal is operated by a control device such as the remote control device to generate a trigger signal, and the trigger signal is transmitted (B) to the trigger time setting means 16 of the parent camera 1a by a transmission means provided in the trigger generator 23 in a communication format according to the TCP / IP protocol.

[0101] In the figure, B indicates communication of a trigger signal.

[0102] Then, the trigger time setting means 16 that has received the trigger signal (B) generates a trigger time. The trigger time generated by the trigger time setting means 16 is notified to the trigger time receiving means 19 (note that in this case, part of the functions of the frame associating means 20 may constitute the trigger time receiving means 19) of the one camera 1 (parent camera 1a), and may also be transmitted by the trigger time transmitting means to another camera 1 (child camera 1b) via wire 24 or wirelessly.

[0103] The above-mentioned wired connection includes both an electric signal cable and a communication cable. The communication cable includes, for example, a network cable, a LAN cable, and a serial cable.

[0104] Furthermore, the trigger time setting means 16 may be provided in a plurality of other cameras 1 in addition to the one camera 1a.

[0105] Instead of connecting the parent camera 1a and the trigger generator 23 by a transmission means in a communication format based on the TCP / IP protocol, as shown in FIG. 6, the trigger generator 25, which generates a trigger signal from the electrical signal input unit, and the parent camera 1a may be connected by an electrical signal cable 26 such as a BNC cable without the use of an electronic device.

[0106] In this case, the time when the trigger generator 25 is operated can be synchronized with the time when the parent camera 1a receives the trigger signal.

[0107] 7 shows yet another method for transmitting the trigger time to each camera, in which the time synchronization means is omitted.

[0108] The example in Figure 6 above shows an example in which parent camera 1a has trigger time setting means 16, but in the example in Figure 7 above, the trigger time setting means 16 may be provided in equipment 27 that is a device separate from parent camera 1a, and parent camera 1a may transmit the trigger time received (A) from the separate device 27 to child camera 1b via cable 24 or wirelessly.

[0109] 8 shows yet another method for transmitting the trigger time to each camera, in which the time synchronization means is omitted.

[0110] As shown in FIG. 8 above, one camera 1 (parent camera 1a) may transmit (A) the received or generated trigger time via wired or wireless connection to a separate device 28 such as a tablet, and the device 28 may then transmit (a) the trigger time to a trigger time receiving means 19 of another camera 1 (child camera 1b) via wired or wireless connection.

[0111] In the figure, "a" indicates communication at the trigger time between device 28 and child camera 1b.

[0112] In addition, the child camera 1b that receives the trigger time from the parent camera 1a may, as the parent camera 1a, transmit the trigger time to another camera 1 (child camera 1b) via wired or wireless communication, in the same manner as described above.

[0113] Furthermore, the parent camera 1a or the child camera 1b may be connected to another camera via an electric signal cable to transmit a trigger signal.

[0114] Also, the combinations in the above examples may be changed to make connections.

[0115] In the following, in principle, the trigger time setting means 16 is described as a device separate from each high-speed camera, but the same applies when the trigger time setting means 16 is provided in one or more cameras.

[0116] (Explanation of frame association means 20)

[0117] Then, the frame association means 20 of each camera 1 determines whether the current time obtained from the current time generation means 17 has reached the trigger time obtained from the trigger time reception means 19, and if it determines that it has reached the trigger time, sets the image frame at that time as the image frame at the trigger time, i.e., the trigger frame, and then sets a specified image frame based on the image frame at this trigger time, and synchronizes each camera 1 by aligning this specified image frame.

[0118] (Explanation of trigger time setting means 16)

[0119] The trigger time setting means 16 is provided, for example, in a device separate from each high-speed camera 1, or in one or more high-speed cameras 1.

[0120] The trigger time setting means 16 is composed of, for example, a timer, a trigger signal input unit, a trigger time generating means for generating a trigger time, and a trigger time transmitting means.

[0121] The trigger signal input section receives a trigger signal transmitted from a trigger generator that generates a trigger signal.

[0122] In addition, the trigger generator generates a trigger signal when the electrical signal input unit or a trigger button on the remote control device is operated, and transmits the trigger signal to the trigger signal input unit via wired or wireless communication.

[0123] The trigger generator may be provided in the trigger time setting means 16 or may be provided as a separate device.

[0124] When a trigger signal is input to the trigger signal input section, the trigger time generating means generates a trigger time based on the current time when the trigger signal is input and in accordance with predetermined conditions, which will be described later.

[0125] When the trigger time setting means 16 is a device separate from the camera, the timer may be synchronized with the time of a time signal transmitting device or each camera by wireless or wired means.

[0126] Furthermore, in the case where the trigger time setting means 16 is a separate entity, the trigger time setting means 16 may be provided with a current time generating means 17 provided in the camera 1 to generate the current time.

[0127] (Specific examples)

[0128] Next, an example of setting the trigger time and the frame relating means will be described.

[0129] (Explanation of Modification Trigger Time)

[0130] When matching the acquired trigger time with the image frame, the trigger time can be set at the boundary between each image frame, i.e., when the start time or end time of each image frame is reached, and that image frame can be set as the image frame at the trigger time (hereinafter referred to as the "trigger frame"). However, due to errors in the accuracy of the timers of each camera, there may be a discrepancy between the trigger time and the start time or end time of each image frame, which may result in the previous image frame or the next image frame being recognized as the trigger frame, and the synchronization of the frames of each camera may be lost.

[0131] Therefore, in order to eliminate the effects of errors in the accuracy of the time of each camera, for example, a trigger time correction unit may be provided and a corrected trigger time may be used that is set to a time later than the start time and earlier than the end time of the image frame, i.e., away from the boundary between the start and end times of the frame.

[0132] For example, as shown in FIG. 9, if the start time of the image frame you want to use as the trigger time is 10:20:10:000:000 (hours:minutes:seconds:milliseconds:microseconds) and the frame end time is 10:20:10:001:000, rather than setting the trigger time to 10:20:10:000:000, set it to, for example, the middle time of that frame time, 10:20:10:000:500.

[0133] In this manner, for example, by using a modified trigger time that is an intermediate time, synchronization of the cameras is ensured.

[0134] In addition, the trigger time setting unit 16 may be provided with the trigger time correction unit, and the trigger time may be corrected when transmitted from the trigger time setting means 16, or each camera 1 may be provided with the trigger time correction unit, and each camera 1 may correct the trigger time when it receives the trigger time.

[0135] As will be described later, if the recording speeds of the cameras are different and the start and end times of each trigger frame are different, the trigger time correction unit sets the corrected trigger time to be a time between the start and end times of the trigger frame of each camera.

[0136] In the following description, the trigger time is a concept that includes the corrected trigger time.

[0137] (Trigger time setting method 1)

[0138] In method 1, the trigger time generating means for generating the trigger time of the trigger time setting means 16 is set to generate a trigger time a little after the time when a trigger signal is received, and the set trigger time is transmitted to the trigger time receiving means 19 of each camera 1.

[0139] The above-mentioned slightly future time means, for example, a time 10 frames ahead. However, if the recording speed (1 / cycle) of each camera is different, the number of frames until the above-mentioned slightly future time coincides will be different for each camera. Therefore, for example, a time 10 frames ahead for any one of the cameras is set.

[0140] Then, the frame relating means 20 sets the image frame at the trigger time as the trigger frame, and synchronizes the trigger frames of all the cameras.

[0141] That is, in this method 1, all cameras 1 receive the trigger time from the trigger time setting means 16, and taking into account the period until the setting of this trigger time is completed, the trigger time is set to a time slightly ahead of the current time.

[0142] By doing so, after all the cameras have received the trigger time, the time of each camera can pass the trigger time, making it possible to synchronize the trigger frames of each camera.

[0143] 10 shows an example of the above method 1 for two cameras (A, B) operating at a recording speed of 1000 fps. The trigger time setting means 16 receives a trigger signal from outside, and transmits a trigger time that is later than the current time at which the signal was received, for example, 10:20:10:000 (hours: minutes: seconds: milliseconds) (note that in the case of a modified trigger time, it is 10:20:10:000:500 (hours: minutes: seconds: milliseconds: microseconds), which is the midpoint of the image frame. Hereinafter, the modified trigger time will be omitted.) as a command.

[0144] The above command means instruction data used to control the camera. The command may include trigger signal data, and may also include trigger time data to transmit the trigger time. The command may also be included in communication by TCP / IP protocol.

[0145] Camera A receives the command for the trigger time at, for example, the (-2) frame time before the trigger time, and camera B receives it at the (-1) frame time before the trigger time, and the trigger times are set by the command in cameras A and B. This allows the trigger frames of cameras A and B to be matched, since the commands can be set in time for the trigger time even if there is a difference in the time at which each camera receives the command.

[0146] Even if the trigger time is set to a time later than the current time, there is no guarantee that the trigger time setting has been completed for all cameras, so the trigger frame may be shifted for cameras for which the trigger time setting was not completed in time.

[0147] Furthermore, in the case of the above method 1, there will be a slight difference in the number of frames between the frame at the time when the trigger is input (event frame) and the trigger frame at the trigger time.

[0148] (Trigger time setting method 2)

[0149] In method 2, the trigger time generating means for generating the trigger time of the trigger time setting means 16 calculates, for example, when a trigger signal is received, the time of the frame at the end of recording that is preset for each camera from that time, and generates this calculated trigger time. The set trigger time is then transmitted as a command to the trigger time receiving means 19 of each camera 1.

[0150] Note that this method 2 is an example in which the recording time after the event frame (cycle x number of image frames) is the same for all cameras. Note that the cycle (exposure timing) here is 1 / recording speed. Also, the number of image frames above refers to the number of frames from the event frame to the recording end frame.

[0151] That is, for example, this is an example in which the recording speed (or exposure timing; the same applies below) and the number of image frames are the same for all cameras.

[0152] When the recording speed, the number of image frames, and the recording time after the event frame are different, the method 3 described below is used.

[0153] In the second method, the frame relating means 20 sets the image frame at the trigger time as a predetermined image frame, so that the frames at the end of recording of all the cameras match.

[0154] That is, in method 2, the trigger time is set to coincide with the frame at which recording ends, rather than with the event frame, so that the frames of all cameras are synchronized.

[0155] In method 2, for example, the recording image frame number setting unit of the recording unit 6 stops recording in the memory 5 when the trigger time is reached, and records the required number of frames. For example, as shown in Fig. 11, in an example of two cameras (A, B) operated at a recording speed of 1000 fps, the number of frames after the trigger (excluding the trigger frame) is set to 0, and the number of frames before the trigger is set to store the required number of frames (for example, if 500 frames each before and after the event frame are recorded, the total number of frames before the event frame, that is, 1001 frames before the event frame).

[0156] Furthermore, for example, as shown in FIG. 12, in the example of two cameras (A, B) operating at a recording speed of 1000 fps, the frame association means 20 may, for example, set the frame at the end of recording as a trigger frame as described above, and then, by an image frame setting section provided in the frame association means 20, go back from the frame at the end of recording to calculate the event frame at the time when the original trigger signal was input, set this event frame as a specified image frame, and synchronize the cameras 1 by matching the specified image frames.

[0157] As described above, by synchronizing each camera with the trigger time as the final frame of recording, the time allowed for completing the setting of the trigger times for all cameras can be maximized, and the number of cameras for which the trigger time cannot be set in time can be reduced.

[0158] (Method 3 of frame association method)

[0159] As described above, the above method 2 is based on the premise that the recording end frames are aligned when the recording time after the event frame is the same. In this example, the trigger time transmitted to each camera 1 is the same.

[0160] However, the method 3 is a method that assumes both the case where the recording time after the event frame of each camera is the same and the case where it is different. In the method 3, the trigger time setting means 16 calculates the time of the frame at the end of recording set in advance for each camera so that the event frames (for example, the image frame when the trigger signal is transmitted) of each camera match, and sets so as to generate the calculated trigger time for each camera. Then, the trigger time set for each camera is transmitted to the trigger time receiving means 19 of each camera 1, and the image frame setting section of the frame association means 20 of each camera 1 calculates the event frame from the frame at the last recording, and the calculated event frames are matched to synchronize each camera.

[0161] FIG. 13 illustrates a method for matching event frames when, for example, the recording speeds are the same but the number of image frames in each camera is different, as will be described below.

[0162] As shown in FIG. 13, in the case of two cameras (A, B) operating at a recording speed of 1000 fps, where camera A is capable of recording 1001 frames and can record an event frame and 500 frames before and after it, and camera B is capable of recording 2001 frames and can record an event frame and 1000 frames before and after it, camera B sets the trigger time to a time 500 milliseconds ahead (later) than camera A and sets the frame at which recording ends as the trigger frame. After that, the image frame setting unit goes back 500 image frames in camera A to set it as the event frame, and goes back 1000 image frames in camera B to set the event frame so that the timing of the event frames matches in both cameras, thereby synchronizing cameras A and B.

[0163] In this method 3, even if the number of image frames of each camera is different, it becomes possible to synchronize the event frames of each camera.

[0164] FIG. 14 shows a method for matching event frames when, for example, the number of image frames from each camera is the same but the recording speeds are different, and will be described below.

[0165] As shown in Figure 14, there are two cameras (A and B), camera A operates at a recording speed of 1000 fps and camera B operates at a recording speed of 500 fps. Camera A and camera B can each record 1001 frames, and can record an event frame and 500 frames before and after it.

[0166] Since the frame at the end of recording in camera A is 500 milliseconds (1 ms x 500 frames) ahead of the event frame, camera A sets the time 500 milliseconds ahead (delayed) from the time in the event frame as the trigger time, and since the frame at the end of recording in camera B is 1000 milliseconds (2 ms x 500 frames) ahead of the event frame, camera A sets the time 1000 milliseconds ahead (delayed) from the time in the event frame as the trigger time. After setting the frame at the end of recording in each camera as the trigger frame, the image frame setting unit goes back 500 or so image frames in camera A and camera B, respectively, to set the event frame so that the timing of the event frame matches in both cameras, thereby synchronizing camera A and camera B.

[0167] In addition, if the recording speed of each camera is different and the start time and end time of each trigger frame are different, the above-mentioned corrected trigger time is set to be a time between the start time and end time of the trigger frame of each camera.

[0168] For example, in the case where the boundaries of the image frames are set to coincide with the exposure start time and the start times of the image frames are aligned to synchronize each image frame in each camera, the recording speeds are different but the exposure times are the same, when using the above-mentioned modified trigger time, if the recording speeds of the cameras are in an integer multiple relationship, it is preferable to set the time slightly ahead of the frame start time of the camera with the slowest recording speed as the base time. The slightly advanced time is a time greater than 0 and shorter than the time from the start time to the end time of the image frame of the camera with the fastest recording speed, for example, half the time from the start time to the end time of the image frame of the camera with the fastest recording speed.

[0169] For example, if there are three cameras with recording speeds of 500 fps, 1000 fps, and 2000 fps, it is a good idea to use the start time of the 500 fps recording speed (2 millisecond period) as the base time, and set the modified trigger time to the time that is half the frame period (250 microseconds) ahead of the 2000 fps recording speed, which is the fastest.

[0170] For example, as shown in FIG. 15, in the case of two cameras (A, B) with the exposure time of each camera being 1 ms, camera A operating at a recording speed of 1000 fps and camera B operating at a recording speed of 500 fps, the corrected trigger time is set based on the frame boundaries (10:20:09:998:000), (10:20:10:000:000), and (10:20:10:002:000) of camera B, which has a slower recording speed, as the reference, and the time of the next frame when the trigger signal is input among them, that is, the event frame. If the start time of the image frame you want to use as the trigger frame is (10:20:10:000:000), you can set the trigger time to (10:20:10:000:500) by advancing (adding) half a period to the frames (10:20:09:999:000), (10:20:10:000:000), and (10:20:10:001:000) of camera A, which has the fastest recording speed. This will eliminate the effects of errors in the accuracy of the time on each camera, and allow you to set a frame that is common to all cameras as the trigger frame.

[0171] For example, as shown in FIG. 16, when the image frame boundaries are set to coincide with the exposure end times, and the end times of the image frames are aligned to synchronize the image frames, and the exposure time of each camera is set to 1 millisecond, in the case of two cameras (A, B), camera A operating at a recording speed of 1000 fps and camera B operating at a recording speed of 500 fps, the corrected trigger time is set based on the frame boundaries (10:20:09:998:000), (10:20:10:000:000), and (10:20:10:002:000) of camera B, which has a slower recording speed, and the trigger time is set among them. If the time of the frame immediately before the signal was input, in other words the end time of the image frame you want to use as the event frame, is (10:20:10:000:000), then by setting the trigger time to (10:20:10:000:500), which is calculated by subtracting half a period from that time of the frames (10:20:09:999:000), (10:20:10:000:000), and (10:20:10:001:000) of camera A, which has the fastest recording speed, you can eliminate the effects of errors in the accuracy of the time of each camera and set a frame that is common to all cameras as the trigger frame.

[0172] (Comparison between conventional method and the method of the present invention)

[0173] FIG. 17 shows and explains a comparison of the flow between the conventional method and the new method according to the present invention.

[0174] In this example, the trigger time setting means is provided in one camera.

[0175] As shown in FIG. 17, the conventional method and the new method use the same method of controlling the exposure timing using a time signal.

[0176] That is, a current time signal is input from a BNC connector. A 1 Hz signal is generated in a Time Control section of the current time generating means 17. Then, from the generated 1 Hz signal, a signal equally divided into a frequency of the recording speed (hereinafter referred to as a VD signal; in FIG. 2, for example, 1000 Hz) is generated in a phase locked loop (PLL) of the exposure signal generating means 18. From the VD signal, an exposure start signal is generated in a Frame Control section of the exposure signal generating means 18, which is input to an Image Sensor (imager section 4), whereby recording is performed at a predetermined exposure timing, and image data is read out from the Image Sensor and recorded in a ring buffer in an Image Memory section (recording memory 5).

[0177] The frames to be recorded are managed so that recording is stopped by inputting a trigger time into the Frame Remain section (recording section 6) and the number of frames before and after the designated trigger are recorded.

[0178] The conventional method and the new method differ in the method of generating the trigger time to be input to the Frame Remain unit (recording unit 6).

[0179] In the conventional method, a trigger signal is input from a BNC connector via an electrical signal cable, the trigger signal is input to the Trigger Control section, and the trigger signal is input to the Frame Remain section (recording section 6). Based on this point, recording to the recording memory is stopped under specified conditions.

[0180] In the new method, the CPU generates a trigger time for the event frame, and based on that trigger time, the Time Register regenerates trigger times so that the event frames of multiple cameras are the same.

[0181] By inputting the trigger time to the Time Control section, a trigger signal is generated when the trigger time is reached, and the trigger signal is input to the Frame Remain section (recording section 6), making it possible to synchronize the trigger frames of each camera. This eliminates the need to input a trigger signal via a BNC connector. EXAMPLES

[0182] (Explanation of Overall Configuration of Example 2)

[0183] Hereinafter, a description will be given of Example 2. Note that parts that are not particularly described are the same as those in Example 1, and so description will be omitted.

[0184] In a second embodiment of the present invention, the camera synchronization means in the first embodiment is configured by a sequence number synchronization means, and the synchronization signal setting means which sets (generates) the synchronization signal and transmits it to each required high-speed camera 1 is configured by a sequence number match time setting means and a trigger sequence number transmission means.

[0185] The sequence number match time setting means is configured to set (generate) a sequence number match time that sends a signal to each high-speed camera in sequence to set the sequence number assigned to each recorded image frame to a specified number, and to transmit the signal to each required high-speed camera 1.

[0186] The trigger sequence number transmitting means is configured to generate and transmit a trigger sequence number corresponding to an image frame for which a trigger signal is to be transmitted.

[0187] That is, in the second embodiment of the present invention, first, the time axis of the timer of each high-speed camera is synchronized, and then, by exposing at a predetermined exposure timing (period) in accordance with the time axis, the image frames of each camera are synchronized. Then, the sequence number match time setting means transmits the same sequence number match time to each camera, and when each camera reaches the sequence number match time, the sequence numbers of the image frames of each high-speed camera are matched to the set predetermined number, so that the sequence numbers of each high-speed camera become matched. Next, the trigger sequence number transmitting means transmits a trigger sequence number for transmitting the same trigger signal to each high-speed camera, and when the sequence number of each high-speed camera reaches the transmitted trigger sequence number, a trigger signal is transmitted to the recording unit of the high-speed camera, thereby synchronizing the image frames of each camera.

[0188] The sequence number match time setting means and the trigger sequence number transmission means may be provided in different devices, in the same device, or in a high-speed camera, among other patterns.

[0189] (Explanation of sequence number synchronization method)

[0190] The sequence number synchronization means comprises a sequence number setting unit which assigns numbers in sequence to the image frames recorded in the recording memory in a ring buffer at a set predetermined exposure timing, a current time generation means 17 which synchronizes the timer of the system control unit 7 with a current time signal (time code) sent at regular low resolution timing from an external device other than each high-speed camera, such as a time signal transmission device 13, and further divides a predetermined time into equal intervals based on the current time signal to generate a high resolution current time, an exposure signal generation means 18 which generates an exposure signal for capturing an image according to the exposure timing set by the current time generation means 17 based on the current time divided into equal intervals, a sequence number match time receiving means which receives the sequence number for triggering, and a frame associating means 20 which associates a synchronization signal consisting of the sequence number match time received by the sequence number match time receiving means and the sequence number for triggering received by the sequence number for triggering receiving means with a predetermined image frame captured and recorded by exposure by the exposure signal generation means 18.

[0191] The frame association means 20 first judges whether the current time generated by the current time generation means 17 has reached the sequence number match time acquired from the sequence number match time acceptance means, and if it judges that the current time has reached the time, sets the sequence number of each high-speed camera to a predetermined value, for example, by setting (resetting) it to 0 by a sequence number agreement unit such as a reset unit that resets the sequence number, thereby making the sequence numbers of each high-speed camera match. Then, when the sequence number of each high-speed camera reaches the trigger sequence number accepted by the trigger sequence number acceptance means, the image frame at that time is set as the image frame for the trigger sequence number, and a trigger signal is transmitted to the recording unit 6, and the image frames for this trigger sequence number are matched, thereby synchronizing each camera 1.

[0192] The sequence number match time setting means and the trigger sequence number transmission means are configured and function in the same manner as the trigger time setting means 16 of the first embodiment, and are connected to each camera, etc., either wired or wirelessly, in the same manner as the first embodiment.

[0193] In addition, the sequence number match time receiving means and the trigger sequence number receiving means are each configured and function in the same manner as the trigger time receiving means 19 of the first embodiment, and are connected to each camera, etc., either wired or wirelessly, in the same manner as the first embodiment.

[0194] If the exposure timing (or recording speed) of each camera is different, the sequence numbers of each camera at the same time will differ. However, a sequence number correction unit is provided in each camera that regards the sequence numbers as being the same at the same time, and the sequence numbers of each camera at the same time are corrected to be the same, thereby synchronizing the cameras.

[0195] For example, in the case of cameras with different recording speeds, the sequence number correction unit sets the sequence numbers assigned to the cameras so that they are the same at the same time.

[0196] That is, for example, if there are two types of cameras with recording speeds of 1000 fps and 500 fps, the sequence number correction unit will set the sequence number of the 1000 fps camera (the one with the shorter cycle) to advance by 1, for example,

[00]

[01]

[02]

[03] , and the sequence number of the 500 fps camera (twice the cycle) to advance by 2, for example,

[00]

[02]

[04]

[06] , thereby enabling a determination to be made as to whether each camera has reached the same predetermined trigger sequence number.

[0197] As another method, the sequence number correcting section corrects the trigger sequence number for each camera so that the trigger signal is generated at the same time in each camera.

[0198] That is, for example, if there are two types of cameras with recording speeds of 1000 fps and 500 fps, the sequence numbers of both cameras are incremented by 1, for example,

[00]

[01]

[02]

[03] , and the sequence number modification unit modifies the trigger sequence number of the camera with 1000 fps (the one with the shorter cycle). <17> Then, a camera with 500 fps (twice the shorter cycle) <34> So, for a 1000fps camera, the sequence number is <17> In the case of a 500 fps camera, the sequence number is <34> It is determined whether or not the

[0199] (Specific explanation of frame association method)

[0200] For example, as shown in FIG. 18, recording begins with frames [A0] through [A9] in the physical area of ​​the recording memory of camera A, and frames [B0] through [B9] in the physical area of ​​the recording memory of camera B being written in a ring buffer format, and the captured image frames are written sequentially to the recording memory. The sequence number setting unit then assigns sequence numbers

[00] ,

[01] ,

[02] ... to the sequentially recorded image frames.

[0201] Assuming that the times are already synchronized, Fig. 18 shows that the latest sequence numbers at the same time do not yet match between camera A and camera B. In other words, camera A has

[11] , while camera B has

[14] , which is a difference of three frames.

[0202] Here, the sequence number match time setting means sends an instruction (command) to all high-speed cameras via Wi-Fi or the like for the sequence number match time "10:20:10:000:500", such as a reset time to reset the sequence numbers. When each high-speed camera reaches the above time (10:20:10:000:500), as shown in FIG. 19, for example, if the latest sequence number of camera A is

[23] and that of camera B is

[26] , the next sequence numbers of cameras A and B will be reset (reset) to

[00] as shown in FIG. 20, and sequence numbers will be assigned sequentially from there, so that the sequence numbers of camera A and camera B will match and recording will continue.

[0203] Thereafter, the sequence number transmitting means transmits an instruction (command) to all high-speed cameras via Wi-Fi or the like, for example, "Use sequence number

[17] as the trigger frame." As a result, as shown in FIG. 21, when the sequence number of the image frame of each high-speed camera reaches 17, a trigger signal is transmitted. As a result, recording stops at the specified image frame, and the necessary image frames (for example, sequence numbers

[12] to

[21] ) remain before and after the image frame corresponding to the sequence number set by the recorded image frame number setting unit. [Explanation of symbols]

[0204] 1. High-speed camera 1a Parent Camera 1b Child camera 2 Camera body 3. Photographic Lenses 4 Imager section 5 Recording Memory 6. Recording section 7 System Control Unit 8 Image Processing Section 9 Input / output section 10 Power supply section 11 Trigger Generator 12 Electrical signal cable for trigger signal 13 Time signal transmitter 14 Electrical signal cable for time synchronization signal 15 Trigger frame synchronization means 16 Trigger time setting means 17 Current time generation means 18 Exposure signal generating means 19 Trigger time reception means 20 Frame Association Method 21 Wireless time synchronization equipment 21a Electrical signal cable 22 Equipment 23 Trigger Generator 24 Wired 25 Trigger Generator 26 Electrical signal cable 27 Equipment 28 Equipment

Claims

1. a plurality of high-speed cameras each comprising an imager unit which sequentially exposes at a preset exposure timing to capture a target image, a recording memory, a recording unit which, upon input of a trigger signal, records a predetermined image captured by the imager unit as an image frame of digital data in the recording memory, and a system control unit which has a timer and performs various calculations; a synchronization signal setting means for setting a synchronization signal and transmitting the set synchronization signal to each of the high-speed cameras; The system control unit has a camera synchronization means, The camera synchronization means includes: a current time generating means for synchronizing the timer based on a current time signal sent from an external device at regular intervals, generating a current time, and determining the exposure timing based on the current time; a synchronization signal receiving means for receiving a synchronization signal from the synchronization signal setting means; A synchronized camera device consisting of a plurality of high-speed cameras, characterized in that when it is determined that the current time obtained from the current time generating means has reached the synchronization signal received by the synchronization signal receiving means, the synchronized camera device further comprises a frame association means for associating the synchronization signal with the image frame at that time.

2. The synchronization signal setting means sets the synchronization signal and transmits the set synchronization signal to each of the high-speed cameras, a trigger time setting means for setting a time for sending a trigger signal to the recording unit of each of the high-speed cameras and transmitting the set trigger time to each of the high-speed cameras; the camera synchronization means is a trigger frame synchronization means, The synchronization signal receiving means for receiving the synchronization signal from the synchronization signal setting means comprises: a trigger time receiving means for receiving a trigger time from the trigger time setting means, When it is determined that the current time acquired from the current time generating means has reached the synchronization signal received by the synchronization signal receiving means, a frame associating means associates the synchronization signal with the image frame at that time, A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 1, characterized in that when it is determined that the current time obtained from the current time generating means has reached the trigger time received by the trigger time receiving means, the frame association means associates the trigger time with the image frame at that time.

3. The frame association means includes:

3. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 2, characterized in that the synchronized camera device judges whether the current time of the image frame has reached the trigger time acquired from the trigger time receiving means, and if it is judged that the current time of the image frame has reached the trigger time, sets the image frame as the image frame at the trigger time, transmits a trigger signal to the recording unit, and sets a predetermined image frame based on the image frame, and synchronizes each of the high-speed cameras by aligning this predetermined image frame in each of the high-speed cameras.

4. Synchronizing each of the high-speed cameras by synchronizing a predetermined image frame based on the image frame in each of the high-speed cameras means 4. A synchronized camera system comprising a plurality of high-speed cameras according to claim 3, wherein the image frames of the respective cameras at the trigger times are set as predetermined image frames and are matched with each other.

5. Synchronizing each of the high-speed cameras by synchronizing a predetermined image frame based on the image frame in each of the high-speed cameras means 4. A synchronized camera device comprising a plurality of high-speed cameras as described in claim 3, characterized in that the frame association means of each of the cameras is provided with an image frame setting unit which sets an image frame having a predetermined relationship from the image frame at the trigger time of each of the cameras, thereby matching the predetermined image frames set by the image frame setting unit.

6. 4. The synchronized camera system comprising a plurality of high-speed cameras according to claim 3, wherein the predetermined image frame is an event frame of an image frame when a trigger signal is input to each of the cameras.

7. 3. A synchronized camera system comprising a plurality of high-speed cameras according to claim 2, wherein said trigger time is set to a time prior to the time when said trigger time setting means receives the trigger signal.

8. 3. The synchronized camera system comprising a plurality of high-speed cameras according to claim 2, wherein the trigger time is set to the time of an image frame at which recording is to be terminated.

9. The trigger time is set to the time of the image frame when recording is to end. The synchronized camera device consisting of a plurality of high-speed cameras as described in claim 2, characterized in that an image frame setting unit provided in the frame association means of each of the high-speed cameras calculates an event frame, which is the image frame at the time when the trigger signal is input, from the image frame at the trigger time, and synchronizes each of the high-speed cameras by matching these event frames.

10. 3. A synchronized camera system comprising a plurality of high-speed cameras according to claim 2, wherein the trigger times input to the respective cameras are the same.

11. 3. A synchronized camera device comprising a plurality of high-speed cameras as described in claim 2, characterized in that the trigger time of each of the cameras is set to correspond to the exposure timing set for each of the cameras and / or the number of image frames to be recorded and retained in the recording memory.

12. 3. A synchronized camera device comprising a plurality of high-speed cameras as described in claim 2, characterized in that the trigger time is set to be later than the start time and earlier than the end time of each of the image frames for which the trigger time of each of the cameras is set.

13. 13. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 12, characterized in that in the case of cameras in which the recording speed set for each camera is different and the start times of the image frames are aligned to synchronize the image frames of each camera, the trigger time is set to a time obtained by adding a time greater than 0 and shorter than the period (1 / recording speed) of the camera with the fastest recording speed to the start time of the image frame of the camera with the slowest recording speed.

14. 13. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 12, characterized in that in the case of cameras in which the recording speed set for each camera is different and the end times of the image frames of each camera are synchronized by matching the end times of the image frames, the trigger time is set to a time obtained by subtracting a time that is greater than 0 and shorter than the period (1 / recording speed) of the camera with the fastest recording speed from the end time of the image frame of the camera with the slowest image speed.

15. The synchronized camera device consisting of a plurality of high-speed cameras as described in claim 1, characterized in that the current time signal is obtained from a wireless time synchronization device that is connected to each of the high-speed cameras by an electric signal cable without the need for an electronic device and is configured to wirelessly synchronize with each other.

16. 3. A synchronized camera device comprising a plurality of high-speed cameras according to claim 2, wherein said trigger time receiving means receives the trigger time through communication means in a communication format according to the TCP / IP protocol.

17. The synchronized camera device comprising a plurality of high-speed cameras according to claim 16, characterized in that the communication means using the communication format according to the TCP / IP protocol is data communication using the Wi-Fi standard.

18. 17. A synchronized camera system comprising a plurality of high-speed cameras according to claim 16, wherein the communication means in the communication format according to the TCP / IP protocol is data communication according to the Ethernet standard.

19. 3. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 2, further comprising a means for transmitting the trigger time accepted by the trigger time accepting means of at least one of the plurality of high-speed cameras to a device which transmits the trigger time to the trigger time accepting means of the other high-speed cameras.

20. 3. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 2, further comprising a means for transmitting the trigger time accepted by the trigger time accepting means of at least one of the plurality of high-speed cameras to the trigger time accepting means of the other high-speed cameras by wire or wirelessly.

21. The synchronized camera device consisting of a plurality of high-speed cameras according to claim 2, characterized in that the trigger time setting means is provided in a device separate from each of the high-speed cameras, and the trigger time generated by the trigger time setting means is transmitted to each of the high-speed cameras via wired or wireless communication.

22. the trigger time setting means is provided in at least one high-speed camera among the plurality of high-speed cameras, 3. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 2, characterized in that the trigger time generated by the trigger time setting means is notified to the trigger time receiving means of at least one of the high-speed cameras and is also transmitted to the trigger time receiving means of the other high-speed cameras.

23. 23. The synchronized camera device comprising a plurality of high-speed cameras according to claim 22, wherein the trigger time generated by the trigger time setting means is generated based on a trigger signal input to the at least one high-speed camera.

24. The trigger signal is generated by a trigger generator; A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 23, characterized in that the generated signal is transmitted to the trigger time setting means by a communication means in a communication format according to the TCP / IP protocol provided in the trigger generator.

25. The trigger signal is generated by an electrical signal input of a trigger generator; 24. A synchronized camera apparatus comprising a plurality of high-speed cameras as described in claim 23, characterized in that the generated signal is transmitted from the electrical signal input unit to the trigger time setting means via an electrical signal cable without the intervention of an electronic device.

26. the system control unit has a sequence number setting unit which sequentially assigns numbers to image frames recorded in the recording memory at a preset exposure timing; The synchronization signal setting means sets the synchronization signal and transmits the set synchronization signal to each of the high-speed cameras, a sequence number match time setting means for setting (generating) a sequence number match time for setting the sequence number of each of the high-speed cameras to a predetermined number and transmitting the sequence number match time to each of the high-speed cameras; a trigger sequence number transmission means for generating and transmitting a trigger sequence number corresponding to an image frame to which a trigger signal is to be transmitted; the camera synchronization means is a sequence number synchronization means, The synchronization signal receiving means for receiving the synchronization signal from the synchronization signal setting means comprises: a sequence number match time receiving means for receiving a sequence number match time from the sequence number match time setting means; a trigger sequence number receiving means for receiving a trigger sequence number from the trigger sequence number transmitting means, When it is determined that the current time acquired from the current time generating means has reached the synchronization signal received by the synchronization signal receiving means, a frame associating means associates the synchronization signal with the image frame at that time, 2. The synchronized camera device consisting of a plurality of high-speed cameras according to claim 1, further comprising: a frame associating means for, when it is determined that the current time generated by the current time generating means has reached the sequence number match time received by the sequence number match time receiving means, setting the sequence numbers of each high-speed camera to a predetermined value by a sequence number matching unit to make the sequence numbers of each high-speed camera match, and, when it is determined that the sequence numbers of each high-speed camera have reached the trigger sequence number received by the trigger sequence number receiving means, associating the trigger sequence number with the image frame at that time.

27. The frame association means includes:

27. A synchronized camera device consisting of a plurality of high-speed cameras according to claim 26, characterized in that the synchronized camera device judges whether the current time generated by the current time generating means has reached the sequence number match time obtained from the sequence number match time receiving means, and if it is judged that the current time has reached the sequence number match time, sets the sequence number of each high-speed camera to a predetermined value by a sequence number matching unit to match the sequence numbers of each high-speed camera, and when the sequence number of each high-speed camera reaches the trigger sequence number received by the trigger sequence number receiving means, sets the image frame at that time as the image frame for the trigger sequence number, transmits a trigger signal to the recording unit, and synchronizes each of the cameras by matching the image frame for this trigger sequence number.

28. A synchronized camera device consisting of a plurality of high-speed cameras as described in claim 26 or claim 27, characterized in that, when the exposure timing of each of the cameras is different, each camera is provided with a sequence number correction unit that corrects the sequence numbers so that they have the same sequence numbers at the same time.

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