Multiplexer and imaging system

Abstract

This multiplexer 100 comprises an input unit 11 to which a plurality of image signals respectively acquired by a plurality of imaging devices 2 and based on a first data communication standard are inputted, an output unit 14 for outputting image signals based on a second data communication standard the data transfer rate of which is slower than the first data communication standard, and a storage unit 12 for temporarily buffering the plurality of image signals inputted from the input unit 11. With a multiplexer 100 such as this, it is possible to collectively convert the image data acquired by a plurality of imaging devices for which some communication standard is adopted to another data communication standard, and to suppress a delay in data transfers that is caused by conversion.

Description

[Technical Field]

[0001] The present invention relates to a multiplexer that receives a plurality of signal inputs and outputs one signal, and an imaging system using the same. [Background technology]

[0002] Conventionally, when image data captured by an imaging device such as an industrial digital camera is transmitted to a terminal device (such as a general-purpose personal computer or a dedicated processing terminal) for image processing and image display at manufacturing sites of industrial products such as semiconductors, research institutes, universities, hospitals, etc., a mechanism called a multiplexer is used to combine image data captured by a plurality of imaging devices into one or to select and output one of the image data. For example, Patent Document 1 discloses a multiplexer that combines data received from a first camera and data received from a second camera and transmits the combined data to an external device.

[0003] As shown in Non-Patent Document 1, various data communication standards have been established for imaging devices such as industrial digital cameras, and the characteristics and configuration of each imaging device vary depending on the data communication standard adopted. For example, industrial digital cameras that comply with "GigE Vision," one of the data communication standards, require a frame buffer on the data transmission side. Furthermore, because the camera's internal power supply is generated from a 48V superimposed power supply via a transformer, the power circuit is large, resulting in high heat generation. Therefore, the camera's housing must be reasonably large. However, they are easy to use because they can be directly connected to terminal devices such as personal computers via an LAN cable. Meanwhile, industrial digital cameras that comply with "CoaXPress," another data communication standard, require a smaller power circuit because the camera's internal power supply is generated from a 24V superimposed power supply without a transformer. Furthermore, they do not require a frame buffer, allowing for a smaller housing than industrial digital cameras that adopt the "GigE Vision" standard. While this has the advantage of allowing the camera to be used even in restricted installation environments, they also require a grabber board on the image data receiving side in order to process the image data on the terminal device.

[0004] In systems that transmit image data acquired by an imaging device such as an industrial digital camera to a terminal device such as a personal computer for image processing and image display, imaging devices that comply with the "GigE Vision" standard are generally being adopted, taking into account their feature of being able to be directly connected to the terminal device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 183706 [Non-patent literature]

[0006] [Non-Patent Document 1] "Machine Vision Interface Standard" (issued January 2014, Japan Industrial Imaging Association, http: / / jiia.org / wp-content / themes / jiia / pdf / fsf.pdf) Summary of the Invention [Problem to be solved by the invention]

[0007] On the other hand, when there is a limit to the installation space for the imaging device, there is a need to use an imaging device with a small housing, such as an industrial digital camera that complies with the "CoaXPress" standard. When using an imaging device that complies with the "CoaXPress" standard, in order to accept image data on the terminal device, it is possible to prepare a separate "CoaXPress" grabber board or to convert the image data into another medium that the host device has, such as "GigE Vision." However, preparing a "CoaXPress" grabber board increases costs, and if a conversion device is used, in a system using multiple imaging devices, there is the problem that preparing a conversion unit for each imaging device also increases costs.

[0008] Furthermore, the data transfer speeds stipulated by each data communication standard vary. For example, if the data communication standard for an imaging device is "CoaXPress," even when transferring image data at the slowest speed, the data transfer speed is standardized to 1.25 Gbps (effective transfer speed is about 1 Gbps). On the other hand, the "GigE Vision" standard has a maximum data transfer speed of 1 Gbps (effective transfer speed is about 900 Mbps). Therefore, when converting the image data interface from "CoaXPress" to "GigE Vision," there is a problem of insufficient communication bandwidth. In particular, when image data sent from multiple imaging devices is sent together to a single terminal device, the lack of communication bandwidth becomes even more pronounced.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a multiplexer that can collectively convert image data acquired by multiple imaging devices that adopt a certain data communication standard into another data communication standard and can suppress delays in data transfer caused by the conversion. Another aim of the present invention is to provide an imaging system that includes multiple such multiplexers and can suppress deviations in imaging timing. [Means for solving the problem]

[0010] In order to achieve the above object, firstly, the present invention provides a multiplexer comprising: an input unit to which a plurality of image signals based on a first data communication standard acquired by a plurality of imaging devices are input; an output unit to output image signals based on a second data communication standard having a data transfer rate slower than that of the first data communication standard; a processing unit to convert the plurality of image signals based on the first data communication standard input to the input unit into image signals based on the second data communication standard; and a memory unit to temporarily buffer the plurality of image signals input from the input unit (Invention 1).

[0011] According to this invention (Invention 1), in a system using multiple imaging devices employing a first data communication standard, when converting to a second data communication standard having a slower data transfer rate than the first data communication standard, it is possible to perform interface conversion of image data from multiple devices using a single unit, without providing a separate conversion unit for each imaging device. Furthermore, even if the data transfer rate of the first data communication standard is faster than that of the second data communication standard, input image data can be temporarily stored in a storage unit, thereby avoiding overflow due to insufficient bandwidth on the output side. In this way, image data acquired by multiple imaging devices employing the first data communication standard can be collectively converted to the second data communication standard, thereby suppressing delays in data transfer due to conversion.

[0012] In the above invention (invention 1), the first data communication standard may be CoaXPress, and the second data communication standard may be GigE Vision (invention 2).

[0013] According to this invention (Invention 2), it is possible to accept image data input from multiple imaging devices that comply with the "CoaXPress" standard, and output data to be sent to a terminal device for image processing in the "GigE Vision" standard, making it possible to build an imaging system that has a high degree of freedom in the installation location of the imaging devices and a simple device configuration.

[0014] In the above inventions (Inventions 1 and 2), when each of the plurality of imaging devices is an nth imaging device (n=1 to m), and packet data input to the input unit from the nth imaging device (n=1 to m) is each nth packet data (n=1 to m), the output unit sequentially outputs image signals based on the second data communication standard converted from the first packet data input to the input unit from the first imaging device, through image signals based on the second data communication standard converted from the mth packet data input to the input unit from the mth imaging device, and the nth packet data (n=1 to m) may be data smaller than one screen's worth of image data captured by each of the nth imaging devices (n=1 to m) (Invention 3).

[0015] Furthermore, in the above invention (Invention 3), the nth packet data (n=1 to m) may be image data for one pixel, multiple pixels, one line, or multiple lines constituting one screen captured by each of the nth imaging devices (n=1 to m) (Invention 4).

[0016] When multiple imaging devices capture images simultaneously, image data is input to the input unit simultaneously from each imaging device, but if the image data for one screen captured by each imaging device is accumulated before interface conversion and output, the more images captured simultaneously, the more the synchronicity of the captured images is lost and the transfer timing of the image data is delayed. According to such inventions (Inventions 3 and 4), by sequentially outputting image data in units smaller than the image data for one screen captured by each imaging device, such as packet data units input from each imaging device to the input unit, or units of one pixel, multiple pixels, one line, or multiple lines constituting one screen captured by each imaging device, it is possible to sequentially perform interface conversion and output image data without waiting for the image data for one screen captured by each imaging device to be accumulated, so that the image data can be transferred while minimizing the loss of synchronicity of the captured images and suppressing delays in the transfer timing of the image data.

[0017] Secondly, the present invention provides an imaging system having a plurality of multiplexers according to the above inventions 1 to 4, with a plurality of imaging devices connected to each of the multiple multiplexers, and further comprising a synchronization means for synchronizing the time of each of the multiple multiplexers (invention 5).

[0018] Some data communication standards for image data, such as the "GigE Vision" standard, do not guarantee delay times along the transmission path. In a system equipped with multiple multiplexers, each of which is connected to multiple imaging devices, if the multiplexers and the image processing terminal device are connected using such a data communication standard, simultaneous imaging using the multiple imaging devices connected to each multiplexer will result in a difference in imaging timing due to the difference in delay time between each multiplexer system. According to this invention (Invention 5), the synchronization means synchronizes the times of the multiple multiplexers, thereby synchronizing the times of the multiple imaging devices connected to each multiplexer, thereby enabling simultaneous imaging using the multiple imaging devices without any time difference.

[0019] In the above invention (Invention 5), it is preferable that the synchronization means synchronizes the time of each of the multiple multiplexers using a time synchronization protocol (Invention 6).

[0020] According to this invention (Invention 6), it is possible to synchronize the time of the entire system using the time of one of the multiplexers and imaging devices that make up the system, or the time of a terminal device connected to the system for image processing, without providing a separate mechanism within the system that sends a synchronization signal to the multiplexer. [Effects of the Invention]

[0021] The multiplexer of the present invention can convert image data acquired by multiple imaging devices that adopt a certain data communication standard into another data communication standard at once, and can suppress delays in data transfer caused by the conversion. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic configuration diagram of an imaging system including a multiplexer according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic configuration diagram of a multiplexer according to the embodiment. [Figure 3] FIG. 2 is a schematic diagram for explaining the processing of image data in a multiplexer. [Figure 4] FIG. 2 is a schematic configuration diagram of an imaging system including two multiplexers according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are examples, and the present invention is not limited to these embodiments.

[0024] FIG. 1 is a schematic diagram of an imaging system 100 including a multiplexer 1 according to an embodiment of the present invention. The imaging system 100 is configured by connecting multiple imaging devices 2 to an input unit 11 of the multiplexer 1 via cables. In this embodiment, four imaging devices 2 (2a, 2b, 2c, and 2d) are connected to the multiplexer 1. Specifically, the input unit 11 of the multiplexer 1 is composed of four input units: a first input unit 11a, a second input unit 11b, a third input unit 11c, and a fourth input unit 11d. The first input unit 11a is connected to the first imaging device 2a, the second input unit 11b is connected to the second input unit 11b, the third imaging device 2c is connected to the third input unit 11c, and the fourth input unit 11d is connected to the fourth imaging device 2d. By connecting a terminal device 200 to the output unit 14 of the multiplexer 1, the imaging system 100 is configured to be able to transfer image data acquired by the imaging devices 2 to the terminal device 200. The number of imaging devices 2 connected to the multiplexer 1 is not particularly limited as long as it is plural, and the number of input units 11 provided in the multiplexer 1 is also not particularly limited as long as it is plural. It is also permissible for the number of imaging devices 2 connected to be less than the number of input units 11 provided in the multiplexer 1 (that is, there may be an input unit among the plural input units 11 to which no imaging device 2 is connected).

[0025] In this embodiment, the imaging devices 2 are industrial digital cameras that comply with the "CoaXPress" standard, and the four imaging devices 2 (2a, 2b, 2c, and 2d) are connected to the first input section 11a, the second input section 11b, the third input section 11c, and the fourth input section 11d of the multiplexer 1 using general-purpose coaxial cables. Illumination devices (not shown) that illuminate the respective imaging targets are connected to the four imaging devices 2 (2a, 2b, 2c, and 2d), and an illumination control signal that controls the on / off of the illumination is sent from the terminal device 200 to each illumination device via the multiplexer 1 and each imaging device 2.

[0026] The terminal device 200 performs image processing and image display based on image data transmitted from the imaging system 100, and also outputs control signals to the imaging system 100 for controlling the imaging device 2 and lighting devices that constitute the imaging system 100. The terminal device 200 may be, for example, a general-purpose personal computer, or may be an operation terminal dedicated to the imaging system 100. The terminal device 200 is configured to be able to accept image data output in accordance with the "GigE Vision" standard, and is connected to the output unit 14 of the multiplexer 1 via a general-purpose LAN cable. An operator of the imaging system 100 can issue various instructions to the imaging system 100 by operating the terminal device 200.

[0027] 2, the multiplexer 1 according to this embodiment includes an input unit 11 to which a plurality of image signals based on a first data communication standard acquired by a plurality of image capture devices are input, an output unit 14 that outputs image signals based on a second data communication standard having a slower data transfer rate than the first data communication standard, a processing unit 13 that converts the plurality of image signals based on the first data communication standard input to the input unit 11 into image signals based on the second data communication standard, a storage unit 12 that temporarily buffers the plurality of image signals input from the input unit 11, and a power supply unit 15 that supplies power to four image capture devices 2 (2a, 2b, 2c, 2d) connected to the multiplexer 1. In this embodiment, the first data communication standard is the "CoaXPress" standard, and the second data communication standard is the "GigE Vision" standard.

[0028] The input unit 11 is composed of four input units, a first input unit 11a, a second input unit 11b, a third input unit 11c, and a fourth input unit 11d, each assigned to one of the four imaging devices 2 (2a, 2b, 2c, 2d). The first input unit 11a, the second input unit 11b, the third input unit 11c, and the fourth input unit 11d all have an interface structure (connector) adopted by the "CoaXPress" standard, and the four imaging devices 2 (2a, 2b, 2c, 2d) are connected via coaxial cables.

[0029] The storage unit 12 is a memory device, so-called frame memory, for storing one screen's worth of image data input from the input unit 11, and may be realized by a DRAM or an SRAM. In this embodiment, the storage unit 12 independently stores the image data input from the first input unit 11a, the second input unit 11b, the third input unit 11c, and the fourth input unit 11d, and independently outputs each piece of image data to the processing unit 13, which will be described later.

[0030] The processing unit 13 is a processor for converting and synthesizing image data and controlling the imaging device 2, and may be implemented by an FPGA, a CPU, or the like. The processing unit 13 provides functions such as various processes on image signals input from the imaging device 2, sending and receiving control signals to and from the imaging device 2, controlling power supply to the imaging device 2, and controlling on / off of lighting devices. In this embodiment, the processing unit 13 can convert multiple image data based on the "CoaXPress" standard input to the input unit 11 into image data based on the "GigE Vision" standard. The processing unit 13 can also generate composite image data by synthesizing two or more pieces of image data input from the first input unit 11a, the second input unit 11b, the third input unit 11c, and the fourth input unit 11d. The processing unit 13 can also transmit control signals that instruct each imaging device 2 to perform imaging, based on control signals received from the terminal device 200.

[0031] The output unit 14 outputs the image data converted into the "GigE Vision" standard by the processing unit 13 to the outside of the multiplexer 1. The output unit 14 has an interface structure (connector) that conforms to the "GigE Vision" standard, and is connected to the terminal device 200 via a LAN cable.

[0032] The power supply unit 15 is a power supply circuit that outputs power to be supplied to the imaging devices 2 (2a, 2b, 2c, and 2d).

[0033] The processing unit 13 of the multiplexer 1 receives, via the output unit 14, a control signal transmitted from the terminal device 200 when the operator operates the terminal device 200, and based on the control signal, can transmit a control signal to each imaging device 2 (2a, 2b, 2c, 2d) so that the imaging device 2 realizes the following functions: (1) Any one of the four imaging devices 2 (2a, 2b, 2c, 2d) is caused to capture an image. (2) Of the four imaging devices 2 (2a, 2b, 2c, 2d), two or more of the imaging devices 2 are caused to simultaneously capture images. (3) The imaging device 2 to be used for imaging is switched.

[0034] According to the multiplexer 1 described above, in a system using four imaging devices 2 that employ the "CoaXPress" standard (first data communication standard), when converting image data from the four imaging devices 2 to the "GigE Vision" standard (second data communication standard), which has a slower data transfer rate than the "CoaXPress" standard, it is possible to perform interface conversion of image data from the four imaging devices 2 using a single unit, without providing a separate conversion unit for each of the four imaging devices 2. Furthermore, even if the data transfer rate of the "CoaXPress" standard is faster than that of the "GigE Vision" standard, the input image data can be temporarily stored in the storage unit 12, thereby resolving bandwidth shortages on the output side. In this way, image data acquired by the four imaging devices 2 that comply with the "CoaXPress" standard can be collectively converted to the "GigE Vision" standard, and delays in data transfer due to conversion can be suppressed.

[0035] Furthermore, by utilizing such a multiplexer 1, it is possible to accept image data input from multiple imaging devices 2 that comply with the "CoaXPress" standard and output data to be sent to the terminal device 200 in the "GigE Vision" standard, making it possible to construct an imaging system 100 that has a high degree of freedom in the installation location of the imaging devices 2 and a simple device configuration.

[0036] When multiple imaging devices 2 simultaneously capture images, image data from each imaging device 2 is simultaneously input to the input unit 11 of the multiplexer 1. However, if image data for one screen captured by each imaging device 2 is accumulated and then interface-converted and output, the more images captured simultaneously, the more the synchronicity of the captured images is lost and the transfer timing of the image data is delayed. To solve this problem, the multiplexer 1 according to this embodiment is configured such that the output unit 14 outputs image signals based on a second data communication standard ("GigE Vision") for each line of an image formed by image signals based on a first data communication standard ("CoaXPress") input to the input unit 11. With this multiplexer 1, for example, when image data from four imaging devices 2 (2a, 2b, 2c, 2d) is collectively sent to the terminal device 200, delays can be reduced by repeatedly sending the image data for each imaging device 2 in sets of four, one line at a time, rather than sending the image data for each imaging device 2 in complete form for one screen in sequence.

[0037] Specifically, when image data for one image consisting of N lines is input to the input unit 11 simultaneously from the first imaging device 2a, the second imaging device 2b, the third imaging device 2c, and the fourth imaging device 2d, the output unit 14 successively outputs image data based on the "GigE Vision" standard corresponding to the image data for the Mth line (M=1 to N) input from the first imaging device 2a to the input unit 11a, image data based on the "GigE Vision" standard corresponding to the image data for the Mth line (M=1 to N) input from the second imaging device 2b to the input unit 11b, image data based on the "GigE Vision" standard corresponding to the image data for the Mth line (M=1 to N) input from the third imaging device 2c to the input unit 11c, and image data based on the "GigE Vision" standard corresponding to the image data for the Mth line (M=1 to N) input from the fourth imaging device 2d to the input unit 11d.

[0038] 3, if the image data input from the first imaging device 2a to the input unit 11a is image data for one image consisting of N lines, then the image data for line 1 is designated as PDa1, the image data for line 2 is designated as PDa2, the image data for line 3 is designated as PDa3, ..., the image data for line N is designated as PDaN. Similarly, for the image data input from the second imaging device 2b to the input unit 11b, the image data for line 1 is designated as PDb1, the image data for line 2 is designated as PDb2, the image data for line 3 is designated as PDb3, ..., the image data for line N is designated as PDbN. For the image data input from the third imaging device 2c to the input unit 11c, the image data for line 1 is designated as PDc1, the image data for line 2 is designated as PDc2, the image data for line 3 is designated as PDc3, ..., the image data for line N is designated as PDcN. For the image data input from the fourth imaging device 2d to the input unit 11d, the image data for line 1 is designated as PDd1, the image data for line 2 is designated as PDd2, the image data for line 3 is designated as PDd3, ..., the image data for line N is designated PDdN.

[0039] Here, the processing unit 13 of the multiplexer 1 outputs from the output unit 14 a set of image data PDa1 for line 1 input from the first imaging device 2a to the input unit 11a, image data PDb1 for line 1 input from the second imaging device 2b to the input unit 11b, image data PDc1 for line 1 input from the third imaging device 2c to the input unit 11c, and image data PDd1 for line 1 input from the fourth imaging device 2d to the input unit 11d, and thereafter repeatedly generates an image data set for line 2 (PDa2, PDb2, PDc2, PDd2), an image data set for line 3 (PDa3, PDb3, PDc3, PDd3), ... and outputs these from the output unit 14. By performing this processing, by outputting image data in units of an image line, it is possible to perform interface conversion and output each time one line's worth of image data is accumulated without waiting for the accumulation of one screen's worth of image data captured by each imaging device 2, thereby suppressing delays in the timing of image data transfer.

[0040] Note that while the output of image signals in units of lines of an image has been described above using an example in which image data for one image consisting of N lines is simultaneously input from the first imaging device 2a, the second imaging device 2b, the third imaging device 2c, and the fourth imaging device 2d, delays in the timing of image data transfer can be suppressed by performing similar processing even when, for example, two or three of the four imaging devices 2 simultaneously capture images. That is, when the imaging system 100 is provided with at least two imaging devices 2 and image signals for one image consisting of N lines are simultaneously input to the input unit 11 from at least two imaging devices 2, delays in the timing of image data transfer can be suppressed as long as the output unit 14 continuously outputs an image signal based on the “GigE Vision” standard corresponding to the image signal for the Mth line (M=1 to N) input to the input unit 11 from one imaging device 2 and an image signal based on the “GigE Vision” standard corresponding to the image signal for the Mth line (M=1 to N) input to the input unit 11 from the other imaging device 2.

[0041] In the above explanation, it is assumed that four imaging devices 2 (2a, 2b, 2c, 2d) are connected to the multiplexer 1, but the number of imaging devices 2 connected to the multiplexer 1 is not limited to this, and similar processing is possible if multiple imaging devices 2 are connected. That is, in the multiplexer 1 of this embodiment, when each of the multiple imaging devices 2 is the nth imaging device (n=1 to m) and the packet data of image data input from the nth imaging device (n=1 to m) to the input unit 11 is the nth packet data (n=1 to m), the output unit 14 is configured to sequentially output image signals based on the second data communication standard converted from the first packet data input from the first imaging device to the input unit 11, to image signals based on the second data communication standard converted from the mth packet data input from the mth imaging device to the input unit 11.If the nth packet data (n=1 to m) is smaller than the image data for one screen captured by each of the nth imaging devices (n=1 to m), the interface can be converted sequentially and the image data can be output without waiting for the image data for one screen captured by each imaging device 2 to be accumulated.Therefore, it is possible to transfer image data while minimizing the loss of synchronicity of the captured images and suppress delays in the timing of transferring the image data.

[0042] Furthermore, in the above explanation, each image data captured by each imaging device 2 is sent line by line in succession, and the interface is converted and output each time one line is accumulated without waiting for the image data for one screen captured by each imaging device 2 to be accumulated, but it is also possible to continuously send image data for one pixel, multiple pixels, or multiple lines that make up one screen captured by each imaging device 2. For example, an image signal of the second data communication standard corresponding to image data of four pixels input from the first imaging device 2a to the input unit 11 may be output from the output unit 14, then an image signal of the second data communication standard corresponding to image data of four pixels input from the second imaging device 2b to the input unit 11 may be output from the output unit 14, then an image signal of the second data communication standard corresponding to image data of four pixels input from the third imaging device 2c to the input unit 11 may be output from the output unit 14, then an image signal of the second data communication standard corresponding to image data of four pixels input from the fourth imaging device 2d to the input unit 11 may be output from the output unit 14, or an image signal of the second data communication standard corresponding to image data of one pixel input from the first imaging device 2a to the input unit 11 may be output from the output unit 14, then an image signal of the second data communication standard corresponding to image data of three pixels input from the second imaging device 2b to the input unit 11 may be output from the output unit 14, It is also possible to output from the output unit 14 an image signal of the second data communication standard corresponding to image data of 5 pixels input to the input unit 11 from the imaging device 2c, and then output from the output unit 14 an image signal of the second data communication standard corresponding to image data of 7 pixels input to the input unit 11 from the fourth imaging device 2d; alternatively, it is also possible to output from the output unit 14 an image signal of the second data communication standard corresponding to image data of 5 pixels input to the input unit 11 from the first imaging device 2a, then output from the output unit 14 an image signal of the second data communication standard corresponding to image data of one line input to the input unit 11 from the second imaging device 2b, then output from the output unit 14 an image signal of the second data communication standard corresponding to image data of 5 pixels input to the input unit 11 from the third imaging device 2c, and then output from the output unit 14 an image signal of the second data communication standard corresponding to image data of half a line input to the input unit 11 from the fourth imaging device 2d.In other words, if the nth packet data (n=1 to m), which is packet data of image data input to the input unit 11 from the nth imaging device (n=1 to m), is smaller than the image data for one screen captured by each of the nth imaging devices (n=1 to m), delays in the timing of transferring the image data can be suppressed, so the sizes of the image data output consecutively from the output unit 14 may be uniform or may vary.

[0043] Next, a mechanism for suppressing the occurrence of deviation in imaging timing in the imaging system 100A including two multiplexers 1A and 1B will be described.

[0044] Some data communication standards for image data, such as the "GigE Vision" standard, do not guarantee delay times along the transmission path. In a system including multiple multiplexers 1, each of which is connected to multiple imaging devices 2, and the multiplexers 1 are connected to a terminal device 200 using such a data communication standard, simultaneous imaging using the multiple imaging devices 2 connected to each multiplexer 1 will result in a difference in imaging timing due to the difference in delay time between the multiplexer systems. To solve this problem, when constructing an imaging system including multiple multiplexers 1 as described above, each of which is connected to multiple imaging devices 2, the system preferably includes a synchronization unit that synchronizes the time of each of the multiple multiplexers 1. By synchronizing the time of the multiple multiplexers 1 using the synchronization unit, the time of the multiple imaging devices 2 connected to each multiplexer 1 is also synchronized, allowing simultaneous imaging using the multiple imaging devices 2 without any time difference.

[0045] A specific example of an imaging system equipped with a synchronization unit will be described below. As shown in FIG. 4, the imaging system 100A has two multiplexers 1A and 1B. Four imaging devices 2 are connected to the input sides of the two multiplexers 1A and 1B, respectively, and the output sides of the two multiplexers 1A and 1B are both connected to a terminal device 200. That is, the imaging system 100A has two imaging lines: one consisting of the multiplexer 1A and four imaging devices 2, and the other consisting of the multiplexer 1B and four imaging devices 2. Note that in this embodiment, the imaging system 100A is equipped with two multiplexers 1, and four imaging devices 2 are connected to each multiplexer 1, but this is not limited thereto. Three or more multiplexers 1 may be provided, and two, three, or five or more imaging devices 2 may be connected to each multiplexer 1.

[0046] The imaging system 100A uses a time synchronization protocol, PTP (Precision Time Protocol), as a synchronization means. By performing time synchronization within the network of the imaging system 100A using the time synchronization protocol PTP, it is possible to synchronize the time of the entire imaging system 100A using the time of any one of the multiplexers 1A and 1B and the imaging device 2 that constitute the imaging system 100A, or the time of the terminal device 200 connected to the imaging system 100A, without providing a separate mechanism inside or outside the imaging system 100A that sends a synchronization signal to the multiplexer 1.

[0047] In time synchronization using the time synchronization protocol PTP, at least one of the multiplexers 1A and 1B and the imaging device 2 that make up the imaging system 100A, and the terminal device 200 connected to the imaging system 100A functions as a master device, and the others function as slave devices. The master device is a device that provides time, and the slave devices synchronize their own time with the time of the master device.

[0048] For example, when one of the multiplexers 1A is the master device, the multiplexer 1A transmits a time signal at a certain time T1 for time synchronization to each of the slave devices, that is, the multiplexer 1B and eight imaging devices 2 constituting the imaging system 100A, and the terminal device 200 connected to the imaging system 100A. Based on this time signal, each slave device measures the network delay and calibrates its own clock. Specific clock calibration methods are well known, and a description thereof will be omitted here.

[0049] If the time of the multiplexer 1B and the terminal device 200 are synchronized with the time of the master device, multiplexer 1A, then by sending a command in advance from the terminal device 200 to the multiplexer 1A and the multiplexer 1B so that the multiplexer 1A and the multiplexer 1B send a trigger signal to start shooting at a specified time to the imaging devices 2 connected to them, each imaging device 2 will be able to take images simultaneously at the specified time, and simultaneous imaging by the multiple imaging devices 2 can be achieved without any delays.

[0050] Note that the configuration for synchronizing time using the time synchronization protocol PTP is one example of the synchronization means of the present invention, and the synchronization means is not limited to this as long as it can synchronize the times of the two multiplexers 1 included in the imaging system 100A. For example, a mechanism for transmitting a trigger signal for time synchronization to the two multiplexers 1 may be separately provided, and the times of the two multiplexers 1 may be synchronized based on the trigger signal from that mechanism, or a configuration for synchronizing time using the time synchronization protocol NTP (Network Time Protocol) may be employed.

[0051] The multiplexer 1 according to the present invention and the imaging systems 100 and 100A using the same have been described above, but the present invention is not limited to the above embodiment and various modifications are possible. For example, in this embodiment, the first data communication standard is the "CoaXPress" standard and the second data communication standard is the "GigE Vision" standard, but the data communication standards are not necessarily limited to these. As long as the data transfer rate of the second data communication standard is slower than that of the first data communication standard, a multiplexer having a similar configuration can be expected to achieve the same effects as the multiplexer 1 according to this embodiment. [Explanation of symbols]

[0052] 100, 100A Imaging System 1 Multiplexer 11 Input section 11a First input section 11b Second input section 11c Third input section 11d Fourth input section 12 Storage section 13 Processing section 14 Output section 15 Power supply section 2. Imaging device 2a First imaging device 2b Second imaging device 2c Third imaging device 2d Fourth imaging device 3 Coaxial Cable 4 LAN cables 200 Terminal Device

Claims

1. an input unit to which a plurality of image signals based on the first data communication standard acquired by a plurality of imaging devices are input; an output unit that outputs an image signal based on a second data communication standard having a data transfer rate slower than that of the first data communication standard; a processing unit that converts the plurality of image signals based on the first data communication standard input to the input unit into image signals based on the second data communication standard; a storage unit that temporarily buffers the plurality of image signals input from the input unit, When each of the plurality of imaging devices is an n-th imaging device (n = 1 to m), and packet data input from the n-th imaging device (n = 1 to m) to the input unit is n-th packet data (n = 1 to m), the output unit sequentially outputs image signals based on the second data communication standard converted from the first packet data input to the input unit from a first imaging device to an image signal based on the second data communication standard converted from the m-th packet data input to the input unit from an m-th imaging device, a multiplexer, wherein the nth packet data (n=1 to m) is data smaller than one screen's worth of image data captured by each of the nth imaging devices (n=1 to m);

2. the first data communication standard is CoaXPress, 2. The multiplexer of claim 1, wherein the second data communication standard is GigE Vision.

3. 2. The multiplexer according to claim 1, wherein the nth packet data (n = 1 to m) is image data for one pixel, multiple pixels, one line, or multiple lines constituting one screen captured by each of the nth imaging devices (n = 1 to m).

4. An imaging system comprising a plurality of multiplexers according to any one of claims 1 to 3, and a plurality of imaging devices connected to each of the plurality of multiplexers, An imaging system comprising a synchronization unit that synchronizes the time of each of the multiplexers.

5. 5. The imaging system according to claim 4, wherein the synchronization means synchronizes the time of each of the multiplexers using a time synchronization protocol.

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