Wireless communication system, reception coupler, and x-ray ct device

Abstract

To suppress occurrence of a reception error by reducing a change in characteristic impedance of a transmission line.SOLUTION: A wireless communication system according to the present embodiment includes a transmission line and a coupler. The transmission line transmits a communication signal. The coupler faces the transmission line, has a conductor that receives the communication signal by electromagnetic field coupling with the transmission line, and has such a shape that an end portion of the conductor in an extension direction of the transmission line is more apart from the transmission line than a center portion of the conductor.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The embodiments disclosed in this specification and the drawings relate to a wireless communication system, a receiving coupler, and an X-ray CT apparatus. [Background technology]

[0002] A wireless communication system that performs wireless communication using a near electromagnetic field has been developed. For example, in this wireless communication system, wireless communication is performed using a ring-shaped transmission line that transmits transmission data (communication signal) and a coupler (receiving coupler) that receives the communication signal by electromagnetic field coupling. When the coupler receives the communication signal from the transmission line, the communication signal is reflected at the end of the coupler, and the characteristic impedance of the transmission line changes at the point where the coupler is placed. Here, if the communication signal is reflected multiple times at the end of the coupler, or if a large reflection occurs in the signal received by the coupler, a reception error may occur.

[0003] In a wireless communication system that uses a transmission line and a coupler to perform wireless communication by near electromagnetic fields, a technique is known in which the end of the coupler is made thin to reduce the reflection of the signal received by the coupler, thereby suppressing the occurrence of reception errors. This technique is useful as a technique for reducing the change in the characteristic impedance of the transmission line, but it is necessary to thin the tip of the coupler, and it is not easy to manufacture. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-006523 [Patent Document 2] JP 2014-150651 A Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce the change in characteristic impedance of the transmission line to suppress the occurrence of reception errors. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The wireless communication system according to the present embodiment includes a transmission line and a coupler. The transmission line transmits a communication signal. The coupler has a conductor that faces the transmission line and receives the communication signal by electromagnetic coupling with the transmission line, and the end of the conductor in the extension direction of the transmission line is farther from the transmission line than the center of the conductor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus to which a communication system according to this embodiment is applied. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of the communication system according to the first embodiment. [Diagram 3] FIG. 3 is a diagram for explaining the configuration of the communication system according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the configuration of a coupler in the communication system according to the first embodiment. [Diagram 5] FIG. 5 is a diagram for explaining a problem with a wireless communication system that performs wireless communication using a transmission line and a coupler. [Figure 6] FIG. 6 is a diagram for explaining the effect of the wireless communication system according to the present embodiment. [Figure 7] FIG. 7 is a diagram for explaining another configuration of the coupler in the communication system according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining still another configuration of the coupler in the communication system according to the first embodiment. [Figure 9] FIG. 9 is a diagram for explaining an application example of the coupler in the communication system according to the first embodiment. [Figure 10] FIG. 10 is a diagram for explaining another application example of the coupler in the communication system according to the first embodiment. [Figure 11] FIG. 11 is a diagram for explaining the configuration of a coupler in the communication system according to the second embodiment. [Figure 12] FIG. 12 is a diagram for explaining another configuration of the coupler in the communication system according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the drawings, embodiments of the wireless communication system, the receiving coupler, and the X-ray CT apparatus will be described in detail. Note that the embodiments are not limited to the following embodiments. In principle, the contents described in one embodiment are also applicable to other embodiments.

[0009] The wireless communication system according to this embodiment is applied to, for example, an X-ray computed tomography (CT) apparatus.

[0010] (First embodiment) FIG. 1 is a diagram showing an example of the configuration of an X-ray CT device 100 to which the wireless communication system according to this embodiment is applied. The X-ray CT device 100 collects CT image data of a subject. Specifically, the X-ray CT device 100 rotates an X-ray tube and an X-ray detector substantially around the subject, detects X-rays that have passed through the subject, and collects projection data. Then, the X-ray CT device 100 generates CT image data based on the collected projection data. As shown in FIG. 1, the X-ray CT device 100 includes a gantry device 10, a bed device 30, and a console device 40.

[0011] In this embodiment, the rotation axis of the rotating frame 13 in a non-tilted state or the longitudinal direction of the top board 33 of the bed device 30 is defined as the Z-axis direction. The axial direction that is perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction. The axial direction that is perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. For the sake of explanation, FIG. 1 illustrates the gantry device 10 from multiple directions, and shows a case in which the X-ray CT device 100 has one gantry device 10.

[0012] The gantry device 10 has an X-ray tube 11, an X-ray detector 12, a rotating frame 13, an X-ray high voltage device 14, a control device 15, a wedge 16, a collimator 17, a data acquisition system (DAS) 18, and a fixed frame 19.

[0013] The X-ray tube 11 is a vacuum tube having a cathode (filament) that generates thermoelectrons and an anode (target) that generates X-rays upon impact of the thermoelectrons. The X-ray tube 11 generates X-rays to be irradiated onto the subject P by irradiating thermoelectrons from the cathode to the anode upon application of high voltage from the X-ray high voltage device 14. For example, the X-ray tube 11 may be a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermoelectrons.

[0014] The wedge 16 is a filter for adjusting the amount of X-rays irradiated from the X-ray tube 11. Specifically, the wedge 16 is a filter that transmits and attenuates the X-rays irradiated from the X-ray tube 11 so that the X-rays irradiated from the X-ray tube 11 to the subject P have a predetermined distribution. For example, the wedge 16 is a wedge filter or a bow-tie filter, which is a filter made of processed aluminum or the like so as to have a predetermined target angle and a predetermined thickness.

[0015] The collimator 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 16, and a slit is formed by combining a plurality of lead plates or the like. The collimator 17 may also be called an X-ray aperture. Although FIG. 1 shows a case where the wedge 16 is disposed between the X-ray tube 11 and the collimator 17, the collimator 17 may also be disposed between the X-ray tube 11 and the wedge 16. In this case, the wedge 16 transmits and attenuates the X-rays that are emitted from the X-ray tube 11 and whose irradiation range is limited by the collimator 17.

[0016] The X-ray detector 12 has a plurality of detection elements that detect X-rays. Each detection element in the X-ray detector 12 detects X-rays irradiated from the X-ray tube 11 and passing through the subject P, and outputs a signal corresponding to the detected X-ray dose to the DAS 18. The X-ray detector 12 has, for example, a plurality of detection element rows in which a plurality of detection elements are arranged in a channel direction (channel direction) along an arc centered on the focus of the X-ray tube 11. The X-ray detector 12 has a structure in which, for example, a plurality of detection element rows in which a plurality of detection elements are arranged in the channel direction are arranged in a row direction (slice direction, row direction).

[0017] For example, the X-ray detector 12 is an indirect conversion type detector having a grid, a scintillator array, and an optical sensor array. The scintillator array has a plurality of scintillators. The scintillator has a scintillator crystal that outputs light with a photon amount corresponding to the amount of incident X-rays. The grid is disposed on the X-ray incident side of the scintillator array, and has an X-ray shielding plate that absorbs scattered X-rays. The grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The optical sensor array has a function of converting the amount of light from the scintillator into an electrical signal corresponding to the amount of light, and has an optical sensor such as a photodiode. The X-ray detector 12 may be a direct conversion type detector having a semiconductor element that converts the incident X-ray into an electrical signal.

[0018] X-ray high voltage device 14 has electric circuits such as a transformer and a rectifier, and includes a high voltage generator that generates a high voltage to be applied to X-ray tube 11, and an X-ray control device that controls the output voltage according to the X-rays generated by X-ray tube 11. The high voltage generator may be of a transformer type or an inverter type. X-ray high voltage device 14 may be provided on rotating frame 13 or fixed frame 19. Here, fixed frame 19 is a frame that rotatably supports rotating frame 13, and has a rotation mechanism for rotating rotating frame 13. Here, rotating frame 13 and fixed frame 19 are examples of a "rotating unit" and a "fixed unit", respectively.

[0019] The DAS 18 collects X-ray signals detected by each detection element of the X-ray detector 12. For example, the DAS 18 has an amplifier that performs an amplification process on the electrical signal output from each detection element, and an A / D converter that converts the electrical signal into a digital signal, and generates detection data. The DAS 18 is realized by, for example, a processor. Here, the DAS 18 is an example of a "data collection device."

[0020] The rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 facing each other and rotates the X-ray tube 11 and the X-ray detector 12 by the control device 15. For example, the rotating frame 13 is a casting made of aluminum. Note that the rotating frame 13 can further support an X-ray high voltage device 14, a wedge 16, a collimator 17, a DAS 18, etc. in addition to the X-ray tube 11 and the X-ray detector 12. Furthermore, the rotating frame 13 can further support various components not shown in FIG. 1.

[0021] A communication device is provided on each of the rotating frame 13 and the fixed frame 19, which is a non-rotating part of the gantry 10. For example, data (collected X-ray signals) generated by the DAS 18 is transmitted from the communication device provided on the rotating frame 13 to the communication device provided on the fixed frame 19 by wireless communication, and then transferred to the console device 40. Also, for example, a control signal for the rotating frame 13 transmitted by the console device 40 is transmitted from the communication device provided on the fixed frame 19 to the communication device provided on the rotating frame 13 by wireless communication. The communication device provided on the rotating frame 13 and the communication device provided on the fixed frame 19 constitute a wireless communication system 500, which will be described later.

[0022] The control device 15 has a processing circuit having a CPU (Central Processing Unit) and the like, and a driving mechanism such as a motor and an actuator. The control device 15 receives an input signal from the input interface 43 and controls the operation of the gantry 10 and the bed 30. For example, the control device 15 controls the rotation of the rotating frame 13, the tilt of the gantry 10, the operation of the bed 30 and the tabletop 33, and the like. As an example, the control device 15 rotates the rotating frame 13 around an axis parallel to the X-axis direction according to input inclination angle (tilt angle) information as a control for tilting the gantry 10. The control device 15 may be provided in the gantry 10 or in the console device 40.

[0023] The bed device 30 is a device on which the subject P to be imaged is placed and moved, and includes a base 31, a bed driving device 32, a top plate 33, and a support frame 34. The base 31 is a housing that supports the support frame 34 so that it can move in the vertical direction. The bed driving device 32 is a drive mechanism that moves the top plate 33 on which the subject P is placed, in the longitudinal direction of the top plate 33, and includes a motor, an actuator, etc. The top plate 33, which is provided on the upper surface of the support frame 34, is a plate on which the subject P is placed. Note that the bed driving device 32 may move the support frame 34 in the longitudinal direction of the top plate 33 in addition to the top plate 33.

[0024] The console device 40 has a memory 41, a display 42, an input interface 43, and a processing circuit 44. Although the console device 40 will be described as being separate from the gantry device 10, the gantry device 10 may include the console device 40 or some of the components of the console device 40.

[0025] The memory 41 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, etc. The memory 41 stores, for example, projection data and CT image data. Also, for example, the memory 41 stores a program for enabling a circuit included in the X-ray CT device 100 to realize its function. Note that the memory 41 may be realized by a server group (cloud) connected to the X-ray CT device 100 via a network.

[0026] The display 42 displays various types of information. For example, the display 42 displays various images generated by the processing circuit 44, or displays a GUI (Graphical User Interface) for receiving various operations from an operator. For example, the display 42 is a liquid crystal display or a CRT (Cathode Ray Tube) display. The display 42 may be provided on the pedestal device 10. The display 42 may be a desktop type, or may be configured as a tablet terminal or the like capable of wireless communication with the console device 40 main body.

[0027] The input interface 43 receives various input operations from an operator, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuitry 44. For example, the input interface 43 receives input operations from the operator, such as reconstruction conditions for reconstructing CT image data and image processing conditions for generating post-processed images from CT image data. For example, the input interface 43 is realized by a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touchpad for performing input operations by touching an operation surface, a touchscreen in which a display screen and a touchpad are integrated, a non-contact input circuit using an optical sensor, a voice input circuit, and the like. The input interface 43 may be provided in the gantry device 10. The input interface 43 may also be configured as a tablet terminal or the like capable of wireless communication with the console device 40 main body. The input interface 43 is not limited to only those having physical operation parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the console device 40 and outputs the electrical signal to the processing circuitry 44 is also included in the input interface 43.

[0028] The processing circuitry 44 controls the overall operation of the X-ray CT apparatus 100. For example, the processing circuitry 44 executes a system control function 440, a scan control function 441, a pre-processing function 442, a reconstruction processing function 443, and a display control function 444.

[0029] The system control function 440 controls various functions of the processing circuit 44 based on input operations received from an operator via the input interface 43 .

[0030] The scan control function 441 executes a scan using X-rays on the subject P. For example, the scan control function 441 controls the scan based on an input operation received from an operator via the input interface 43. Specifically, the scan control function 441 controls the output voltage from the high voltage generator by transmitting a control signal to the X-ray high voltage device 14 based on the input operation. In addition, the scan control function 441 controls data collection by the DAS18 by transmitting a control signal to the DAS18.

[0031] The pre-processing function 442 generates pre-processed data by performing pre-processing on the X-ray detection data transmitted from the DAS 18. Specifically, the pre-processing function 442 generates pre-processed data by performing correction processes such as logarithmic conversion, offset correction, sensitivity correction, and beam hardening correction. Note that the data before pre-processing (X-ray detection data) and the data after pre-processing may be collectively referred to as projection data.

[0032] The reconstruction processing function 443 generates CT image data by reconstructing the projection data generated by the pre-processing function 442 using various reconstruction methods (for example, back projection methods such as FBP (Filtered Back Projection), iterative approximation, etc.). In addition, the reconstruction processing function 443 stores the generated CT image data in the memory 41.

[0033] The display control function 444 causes various images generated by the processing circuitry 44 to be displayed on the display 42. For example, the display control function 444 causes the display 42 to display CT image data generated by the reconstruction processing function 443.

[0034] 1, each processing function is stored in the form of a program executable by a computer in the memory 41. The processing circuitry 44 is a processor that realizes a function corresponding to each program by reading and executing the program from the memory 41. In other words, the processing circuitry 44 in a state in which each program has been read has a function corresponding to the read program.

[0035] The term "processor" used in the above description means a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), or an application specific integrated circuit (ASIC). The term "processor" also means a circuit such as a programmable logic device. Examples of programmable logic devices include a simple programmable logic device (SPLD) and a complex programmable logic device (CPLD). Examples of programmable logic devices include a field programmable gate array (FPGA). When the processor is a CPU, for example, the processor realizes a function by reading and executing a program stored in the memory 41. On the other hand, when the processor is an ASIC, for example, instead of storing the program in the memory 41, the program is directly incorporated into the circuit of the processor. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, and may be configured as one processor by combining multiple independent circuits to realize its function. Furthermore, multiple components in FIG. 1 may be integrated into one processor to realize the functions thereof.

[0036] The overall configuration of the X-ray CT apparatus 100 to which the wireless communication system 500 according to this embodiment is applied has been described above.

[0037] FIG. 2 is a diagram showing an example of the configuration of a wireless communication system 500 according to the first embodiment.

[0038] As shown in Fig. 2, the wireless communication system 500 includes a communication device 600 on the rotation side, a ring-shaped transmission path 700, and a communication device 800 on the fixed side. In the example shown in Fig. 2, the communication device 600 and the ring-shaped transmission path 700 are arranged on a rotating part (rotating frame 13), and the communication device 800 is arranged on a fixed part (fixed frame 19). The communication devices 600 and 800 communicate via the ring-shaped transmission path 700. In the example shown in Fig. 2, the rotation direction of the rotating part, the communication device 600 on the rotation side, and the ring-shaped transmission path 700 is clockwise.

[0039] The ring-shaped transmission path 700 has a plurality of transmission paths (hereinafter referred to as segments) that transmit transmission data (communication signals). In the example shown in Fig. 2, the ring-shaped transmission path 700 is configured by dividing it into two segments (hereinafter referred to as a first segment 701 and a second segment 702) at 180° intervals. For example, the ring-shaped transmission path 700 is divided into a second segment 702 that transmits a communication signal in the rotation direction of the rotating part, and a first segment 701 that transmits a communication signal in the opposite direction to the rotation direction.

[0040] The communication device 600 on the rotation side has a rotation communication unit 610 that transmits transmission data (communication signal) including a transmission signal and a clock signal, a signal input unit 620 for inputting a signal (communication signal) to the input end of each transmission line (first segment 701, second segment 702), and a signal termination unit 630 for preventing reflection of the signal at the end of each transmission line. Specifically, the signal input unit 620 is connected to the input end of the first segment 701 and the input end of the second segment 702, and the signal termination unit 630 is connected to the end of the first segment 701 and the end of the second segment 702.

[0041] The rotary communication unit 610 has an 8B10B conversion unit that performs clock signal recovery (restoration, repair) and coding for ensuring DC balance for the transmission data (communication signal). The signal input unit 620 has a differential driver and a distributor for inputting the transmission data to each segment. Note that the coding method is not limited to 8B10B, and other methods such as 64B66B and 128B130B may be used.

[0042] The fixed communication device 800 has a coupler 810 which is an antenna coupler, and a fixed communication unit 820. The coupler 810 receives a communication signal flowing through the ring-shaped transmission line 700 by electromagnetic field coupling. The coupler 810 receives a communication signal from one of the first segment 701 and the second segment 702. The fixed communication unit 820 recovers (restores, restores) a clock signal according to a receiving position where the coupler 810 receives the communication signal from one of the segments. Then, the fixed communication unit 820 generates received data (communication signal) based on a transmission signal included in the communication signal received by the coupler 810 and the recovered clock signal.

[0043] In the example shown in FIG. 2, when the communication device 600 and the ring-shaped transmission path 700 are arranged in the rotating part and the communication device 800 is arranged in the fixed part, the transmission data (communication signal) is an X-ray signal (X-ray detection data) collected by the data collection device (DAS18). In this case, the communication device 800 on the fixed side recovers a clock signal included in the transmission data, and generates reception data (communication signal) based on the transmission data and the recovered clock signal. For example, in the processing circuit 44 of the console device 40, the pre-processing function 442 performs pre-processing on the reception data transmitted from the DAS18 to generate projection data. The reconstruction processing function 443 generates CT image data by reconstructing the projection data generated by the pre-processing function 442.

[0044] In the wireless communication system 500 according to the present embodiment, wireless communication is performed using, for example, a ring-shaped transmission line 700 that transmits transmission data (communication signals) and a coupler 810 that receives the communication signals by electromagnetic field coupling. When the coupler 810 receives the communication signals from the transmission line, the communication signals are reflected at the end of the coupler, and the characteristic impedance of the transmission line changes at the point where the coupler is arranged. Here, if a large reflection occurs in the signal received by the coupler, such as multiple reflection of the communication signals at the end of the coupler, a reception error may occur. Therefore, in order to reduce the reflection of the signal received by the coupler, for example, it is conceivable to make the end of the coupler thin, but this is not easy to manufacture.

[0045] Therefore, the wireless communication system 500 according to the present embodiment includes a transmission line and a coupler. The transmission line transmits a communication signal. The coupler faces the transmission line and has a conductor that receives the communication signal by electromagnetic coupling with the transmission line, and the end of the conductor in the extension direction of the transmission line is farther from the transmission line than the center of the conductor.

[0046] Fig. 3 is a diagram for explaining the configuration of the communication system 500 according to the first embodiment. Fig. 4 is a diagram for explaining the configuration of the coupler 810 of the communication system 500 according to the first embodiment.

[0047] As shown in FIG. 3, signal input unit 620 of rotation-side communication device 600 is configured with a differential transmit buffer, and outputs transmission data (communication signals) SIG+, SIG− input from the above-mentioned rotation communication unit 610 to ring transmission path 700.

[0048] The ring-shaped transmission line 700 has the above-mentioned multiple transmission lines (in the example shown in FIG. 2, a first segment 701 and a second segment 702), and each transmission line has transmission lines 711 and 712 constituting a differential transmission line 710, and a reference potential conductor 720 (GND). The transmission lines 711 and 712 transmit communication signals SIG+ and SIG-, respectively. The communication signals SIG+ and SIG- are differential signals transmitted on the differential transmission line 710. Here, the transmission lines 711 and 712 are examples of "transmission lines".

[0049] The ring-shaped transmission line 700 will be described as a differential microstrip line formed on a dielectric substrate such as FR (Flame Retardant)-4 or PTFE (Polytetrafluoroethylene), but the present invention is not limited to this. For example, the differential transmission line 710 of each transmission line of the ring-shaped transmission line 700 may be another differential transmission line such as a differential coplanar line or a grounded differential coplanar line. In addition, the differential transmission line 710 may be formed by a transmission line patterned on a flexible substrate, and the ring-shaped transmission line 700 may be formed by the differential transmission line 710 and a metal member serving as a reference potential conductor 720.

[0050] In the communication device 800, two couplers 810 are provided for the differential transmission line 710. For example, the two couplers 810 face the transmission lines 711 and 712 constituting the differential transmission line 710, respectively, and receive the communication signals SIG+ and SIG- by electromagnetic field coupling with the transmission lines 711 and 712. In the example shown in Fig. 3, the two couplers 810 receive the communication signals SIG+ and SIG-, respectively, from the transmission lines 711 and 712 constituting the differential transmission line 710 of one segment (first segment 701) of the first segment 701 and the second segment 702 of the ring-shaped transmission line 700. Here, the coupler 810 is an example of a "coupler" or a "receiving coupler".

[0051] As shown in FIG. 3, a fixed communication unit 820 of a communication device 800 includes a waveform shaping unit 821 such as a comparator, a clock signal recovery unit 822, and a generation unit 823 (10B8B conversion unit).

[0052] The waveform shaping unit 821 amplifies the communication signal received by each coupler 810. The clock signal recovery unit 822 recovers (restores, restores) the clock signal included in the communication signal. The generation unit 823 generates received data (communication signal) based on the transmission signal included in the communication signal received by each coupler 810 and the clock signal recovered by the clock signal recovery unit 822.

[0053] In the example shown in FIG. 4, of the transmission lines 711 and 712 that constitute the differential transmission line 710 of the ring-shaped transmission line 700, a coupler 810 that receives a communication signal SIG+ from the transmission line 711 is illustrated.

[0054] 4, coupler 810 has electrode conductor 811, flexible substrate 812 on which electrode conductor 811 is formed, and dielectric member 813 which is a member for holding flexible substrate 812 in a shape described below. Electrode conductors 811 of two couplers 810 face transmission lines 711 and 712, respectively, and receive communication signals SIG+ and SIG- by electromagnetic coupling with transmission lines 711 and 712. Here, electrode conductor 811 is an example of "conductor". Also, dielectric member 813 is an example of "holding member".

[0055] As shown in the side views of Figures 3 and 4, each coupler 810 has a shape in which the end portion of the electrode conductor 811 in the extension direction of the differential transmission line 710 (transmission lines 711, 712) is farther from the differential transmission line 710 than the center portion of the electrode conductor 811.

[0056] 4, the electrode conductor 811 is provided on one of the two main surfaces of the flexible substrate 812. The dielectric member 813 holds the other main surface of the flexible substrate 812 such that the ends XE1, XE2 of the electrode conductor 811 are farther from the transmission line 711 than the center portion XC of the electrode conductor 811.

[0057] In this manner, in the wireless communication system 500 according to this embodiment, the dielectric member 813 holds the flexible substrate 812, on which the electrode conductors 811 are formed, in the above-mentioned shape, so that the coupler 810 can be easily manufactured.

[0058] Here, the reason why coupler 810 is formed in the above-mentioned shape in this embodiment will be explained.

[0059] First, the problems that arise when the coupler is not formed in the above-mentioned shape will be described, and then the effects that arise when coupler 810 is formed in the above-mentioned shape will be described.

[0060] Fig. 5 is a diagram for explaining a problem of a wireless communication system that performs wireless communication using a transmission line and a coupler. Fig. 5 shows an example in which the distance between the electrode conductor 1811 of the coupler 1810 and the differential transmission line 1710 (two transmission lines) is uniform from one end XE11 to the other end XE12 in the extension direction of the differential transmission line 1710 of the electrode conductor 1811. The example shown in Fig. 5 shows a coupler 1810 that receives a communication signal SIG+ from the transmission line 1711, which is one of the two transmission lines that configure the differential transmission line 1710 of the ring-shaped transmission path.

[0061] 5, the inductance of the transmission line 1711 and the reference potential conductor 1720 is "L", the capacitance between the transmission line 1711 and the reference potential conductor 1720 is "C", and the capacitance between the transmission line 1711 and the electrode conductor 1811 of the coupler 1810 is "Cc". Here, in the example shown in Fig. 5, the distance between the electrode conductor 1811 and the transmission line 1711 is uniform from one end XE11 to the other end XE12 of the electrode conductor 1811 in the extension direction of the transmission line 1711, so that the capacitance "Cc" between the transmission line 1711 and the electrode conductor 1811 is uniform from one end XE11 to the other end XE12 of the electrode conductor 1811.

[0062] In the example shown in FIG. 5, when the coupler 1810 receives the communication signal SIG+ from the transmission line 1711, the communication signal SIG+ is reflected at one end XE11 of the coupler 1810, and the characteristic impedance of the transmission line 1711 changes at the location where the coupler 1810 is arranged. For example, at a location where the coupler 1810 is not arranged on the transmission line 1711, the characteristic impedance of the transmission line 1711 is expressed as the square root of L / C. Here, generally, when the resistance is "R", the conductance is "G", the imaginary number is "j", and the angular frequency is "ω", the characteristic impedance of the transmission line is expressed as the square root of (R+jωL) / (G+jωC), but "R" and "G" are negligibly small. For this reason, the characteristic impedance of the transmission line 1711 is expressed as the square root of L / C as a general approximation. On the other hand, at a location where the coupler 1810 is disposed on the transmission line 1711, the characteristic impedance of the transmission line 1711 is expressed as the square root of L / (C+Cc) as a general approximation. It is desirable for a communication signal to be transmitted on the transmission line without reflection, but the characteristic impedance of the transmission line changes significantly at the location where the coupler is disposed. For this reason, the communication signal may be reflected at the end of the coupler, causing a reception error. In the example shown in FIG. 5, the communication signal is multiple-reflected at the ends XE11 and XE12 of the coupler 1810, and the coupler 1810 receives a composite wave of multiple reflections, which may cause a reception error. The higher the communication speed, the more likely it is that reception errors will occur due to reflections, so measures must be taken.

[0063] Fig. 6 is a diagram for explaining the effect of the wireless communication system 500 according to this embodiment. Fig. 6 shows an example of a case where the coupler 810 in this embodiment has a shape in which the ends XE1 and XE2 of the electrode conductor 811 in the extension direction of the differential transmission line 710 (transmission lines 711 and 712) are farther from the differential transmission line 710 than the center part XC of the electrode conductor 811. In the example shown in Fig. 6, the coupler 810 that receives the communication signal SIG+ from the transmission line 711 of the transmission lines 711 and 712 that configure the differential transmission line 710 of the ring-shaped transmission line 700 is shown.

[0064] 6, the inductance of the transmission line 711 and the reference potential conductor 720 is "L", the capacitance between the transmission line 711 and the reference potential conductor 720 is "C", and the capacitance between the transmission line 711 and the electrode conductor 811 of the coupler 810 is "Cc". In the example shown in FIG. 6, the shape of the coupler 810 is such that the ends XE1 and XE2 of the electrode conductor 811 in the extension direction of the transmission line 711 are farther from the transmission line 711 than the center part XC of the electrode conductor 811, so that the capacitance "Cc" between the transmission line 711 and the electrode conductor 811 changes gradually at the location where the coupler 810 is disposed. Specifically, the capacitance "Cc" between the transmission line 711 and the electrode conductor 811 increases from one end XE1 to the center part XC of the electrode conductor 811, and decreases from the center part XC to the other end XE2.

[0065] In the example shown in FIG. 6, when the coupler 810 receives the communication signal SIG+ from the transmission line 711, the characteristic impedance of the transmission line 711 changes gradually at the location where the coupler 810 is arranged. For example, at the location where the coupler 810 is not arranged on the transmission line 711, the characteristic impedance of the transmission line 711 is expressed as a square root of L / C as a general approximation. On the other hand, at the location where the coupler 810 is arranged on the transmission line 711, the characteristic impedance of the transmission line 711 is expressed as a square root of L / (C+Cc) as a general approximation. Here, since the ends XE1 and XE2 of the electrode conductor 811 are shaped to be farther away from the transmission line 711 than the center part XC of the electrode conductor 811, the capacitance "Cc" between the transmission line 711 and the ends XE1 and XE2 of the electrode conductor 811 is smaller than the capacitance "Cc" between the transmission line 711 and the center part XC of the electrode conductor 811. Therefore, in the example shown in FIG. 6, the characteristic impedance of the transmission line 711 changes gradually at the location where the coupler 810 is disposed, making it possible to suppress reception errors due to reflection of the communication signal.

[0066] In this manner, in the wireless communication system 500 according to this embodiment, the coupler 810 is easy to manufacture, and the occurrence of reception errors can be suppressed by reducing changes in the characteristic impedance of the differential transmission line 710 (transmission lines 711, 712) of the ring-shaped transmission line 700.

[0067] 4, the coupler 810 is shaped so that the electrode conductor 811 is curved from one end XE1 to the other end XE2, but the shape of the coupler 810 is not limited to this. For example, only the ends XE1, XE2 of the electrode conductor 811 of the coupler 810 may be curved or bent.

[0068] 7 is a diagram for explaining another configuration of the coupler 810 of the communication system 500 according to the first embodiment. In the example shown in FIG. 7, of the transmission lines 711 and 712 constituting the differential transmission line 710 of the ring-shaped transmission line 700, the coupler 810 that receives the communication signal SIG+ from the transmission line 711 is illustrated. In the example shown in FIG. 7, the coupler 810 has a curved shape such that the ends XE1 and XE2 of the electrode conductor 811 are farther from the transmission line 711 than the central portion XC. Specifically, the central portion XC has a planar shape, and the ends XE1 and XE2 have a curved shape such that they are farther from the transmission line 711 than the central portion XC.

[0069] 8 is a diagram for explaining still another configuration of the coupler 810 of the communication system 500 according to the first embodiment. In the example shown in FIG. 8, of the transmission lines 711 and 712 constituting the differential transmission line 710 of the ring-shaped transmission line 700, the coupler 810 that receives the communication signal SIG+ from the transmission line 711 is illustrated. In the example shown in FIG. 8, the coupler 810 is bent so that the ends XE1 and XE2 of the electrode conductor 811 are farther from the transmission line 711 than the central portion XC. Specifically, the ends XE1 and XE2 and the central portion XC are planar, and further, the ends XE1 and XE2 are bent so as to be farther from the transmission line 711 than the central portion XC.

[0070] In the examples shown in Figures 7 and 8, as in the example shown in Figure 4, the occurrence of reception errors can be suppressed by reducing the change in characteristic impedance of the differential transmission line 710 (transmission lines 711, 712) of the ring-shaped transmission line 700.

[0071] Fig. 9 is a diagram for explaining an application example of the coupler 810 of the communication system 500 according to the first embodiment. In Fig. 9, the coupler 810 and the electrode conductor 811 are described as a "coupler 810A" and an "electrode conductor 811A", respectively.

[0072] In the example shown in FIG. 9, the differential transmission line 710 (transmission lines 711, 712) is a ring-shaped transmission line 700 formed on the inner circumferential side surface (inner circumferential surface) of a ring-shaped housing that is a rotating frame 13. Here, in the example shown in FIG. 9, the electrode conductor 811A of the coupler 810A has a larger curvature than the ring-shaped transmission line 700 so that the ends XE1, XE2 of the electrode conductor 811A are shaped to move away from the differential transmission line 710 (transmission lines 711, 712). Thus, in the example shown in FIG. 9, since the ends XE1, XE2 of the electrode conductor 811A are shaped to move away from the differential transmission line 710, it is possible to reduce the change in characteristic impedance of the differential transmission line 710 (transmission lines 711, 712) of the ring-shaped transmission line 700 and suppress the occurrence of reception errors.

[0073] Fig. 10 is a diagram for explaining another application example of the coupler 810 of the communication system 500 according to the first embodiment. In Fig. 10, the coupler 810 and the electrode conductor 811 are described as "coupler 810B" and "electrode conductor 811B", respectively.

[0074] In the example shown in FIG. 10, the differential transmission line 710 (transmission lines 711, 712) is a ring-shaped transmission line 700 formed on the outer circumferential side surface (outer circumferential surface) of a ring-shaped housing. Here, in the example shown in FIG. 10, the coupler 810B is shaped to be curved from one end XE1 to the other end XE2 of the electrode conductor 811B, so that the ends XE1 and XE2 of the electrode conductor 811B are shaped to move away from the differential transmission line 710 (transmission lines 711, 712). Therefore, in the example shown in FIG. 10, the electrode conductor 811B does not need to have a larger curvature than the ring-shaped transmission line 700. Thus, even in the example shown in FIG. 10, the ends XE1 and XE2 of the electrode conductor 811B are shaped to move away from the differential transmission line 710, so that the change in the characteristic impedance of the differential transmission line 710 (transmission lines 711, 712) of the ring-shaped transmission line 700 can be reduced to suppress the occurrence of reception errors.

[0075] As described above, in the communication system 500 according to the first embodiment, the coupler 810 has an electrode conductor 811 that faces the transmission lines 711, 712 that transmit the communication signals SIG+, SIG- and receives the communication signals SIG+, SIG- by electromagnetic field coupling with the transmission lines 711, 712. The coupler 810 has a shape in which the ends XE1, XE2 of the electrode conductor 811 in the extension direction of the transmission lines 711, 712 are farther from the transmission lines 711, 712 than the center part XC of the electrode conductor 811. As a result, in the wireless communication system 500 according to the present embodiment, the coupler 810 is easy to manufacture, and the occurrence of reception errors can be suppressed by reducing changes in the characteristic impedance of the differential transmission lines 710 (transmission lines 711, 712) of the ring-shaped transmission line 700.

[0076] In this embodiment, the wireless communication system 500 including the transmission lines 711 and 712, which are the ring-shaped transmission line 700, and the above-mentioned coupler 810 has been described as an example of the X-ray CT apparatus 100, but is not limited thereto. For example, the transmission line does not need to be ring-shaped, and this embodiment can be similarly applied to a wireless communication system including a planar transmission line and the above-mentioned coupler 810.

[0077] Second embodiment In the first embodiment, the electrode conductor 811 of the coupler 810 has a rectangular shape. However, the shape is not limited to this.

[0078] Fig. 11 is a diagram for explaining the configuration of a coupler 810 of a communication system 500 according to the second embodiment. In the example shown in Fig. 11, of the transmission lines 711 and 712 constituting the differential transmission line 710 of the ring-shaped transmission line 700, the coupler 810 that receives a communication signal SIG+ from the transmission line 711 is illustrated.

[0079] 11, in a coupler 810, the width of the ends XE1 and XE2 of an electrode conductor 811 in a direction perpendicular to the extension direction of the transmission line 711 is narrower than the width of a central portion XC of the electrode conductor 811 in the perpendicular direction. That is, in the coupler 810, the width of the electrode conductor 811 in a direction perpendicular to the extension direction of the transmission line 711 is wider at the central portion XC of the electrode conductor 811. Furthermore, the coupler 810 has a curved shape such that the ends XE1 and XE2 of the electrode conductor 811 in the extension direction of the transmission line 711 are farther from the transmission line 711 than the central portion XC of the electrode conductor 811.

[0080] 11, in coupler 810, the width of electrode conductor 811 is narrowed toward ends XE1, XE2 of electrode conductor 811, and ends XE1, XE2 of electrode conductor 811 are curved, thereby making it possible to reduce the height of coupler 810. That is, in wireless communication system 500 according to the second embodiment, it is possible to achieve the effects of the first embodiment and to reduce the height of coupler 810.

[0081] The reduction in height of coupler 810 can also be achieved in a case where electrode conductor 811 of coupler 810 has a rhombus shape.

[0082] Fig. 12 is a diagram for explaining another configuration of the coupler 810 of the communication system 500 according to the second embodiment. In the example shown in Fig. 12, of the transmission lines 711 and 712 constituting the differential transmission line 710 of the ring-shaped transmission line 700, the coupler 810 that receives the communication signal SIG+ from the transmission line 711 is illustrated.

[0083] 12, in a coupler 810, the width of ends XE1, XE2 of an electrode conductor 811 in a direction perpendicular to the extension direction of a transmission line 711 is tapered from a central portion XC of the electrode conductor 811 toward the ends XE1, XE2. Furthermore, the coupler 810 is curved such that the ends XE1, XE2 of the electrode conductor 811 in the extension direction of the transmission line 711 are farther from the transmission line 711 than the central portion XC of the electrode conductor 811.

[0084] 12, in coupler 810, electrode conductor 811 is shaped like a rhombus and ends XE1, XE2 of electrode conductor 811 are curved, thereby making it possible to reduce the height of coupler 810. That is, even in the example shown in FIG 12, the effect of the first embodiment can be achieved and coupler 810 can be made low-profile.

[0085] (Other embodiments) Although the embodiment has been described above, the present invention may be embodied in various different forms other than the above-described embodiment.

[0086] In addition, in the above-described embodiment, the communication device 600 and the ring-shaped transmission path 700 are arranged in the rotating part (rotating frame 13), the communication device 800 is arranged in the fixed part (fixed frame 19), and the transmission data (communication signal) is an X-ray signal collected by the data collection device (DAS 18) is described as an example, but this is not limited to the above.

[0087] For example, when the communication device 600 and the ring-shaped transmission path 700 are arranged in a fixed part and the communication device 800 is arranged in a rotating part, the transmission data (communication signal) is a control signal for the rotating part transmitted by the console device 40 of the X-ray CT device 100.

[0088] In addition, each component of each device illustrated in the present embodiment is a functional concept, and does not necessarily have to be physically configured as illustrated. In other words, the specific form of distribution and integration of each device is not limited to that illustrated, and all or a part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions. Furthermore, each processing function performed by each device can be realized in whole or in any part by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0089] The method described in this embodiment can be realized by executing a prepared program on a computer such as a personal computer or a workstation. This program can be distributed via a network such as the Internet. This program can also be recorded on a non-transitory computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, or a DVD, and executed by being read from the recording medium by a computer.

[0090] According to at least one of the embodiments described above, it is possible to reduce the change in characteristic impedance of the transmission line and suppress the occurrence of reception errors.

[0091] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0092] 500 Wireless communication system 710 Differential Transmission Line 711 Transmission Line 712 Transmission Line 810 Coupler (receiving coupler) 811 Electrode conductor

Claims

1. A transmission line for transmitting a communication signal; a coupler including a conductor facing the transmission line and receiving the communication signal by electromagnetic coupling with the transmission line, the conductor having an end portion in an extension direction of the transmission line being farther from the transmission line than a center portion of the conductor; A wireless communication system comprising:

2. the coupler has a curved or bent shape such that the end portion of the conductor is farther from the transmission line than the central portion of the conductor; 2. The wireless communication system according to claim 1.

3. The coupler includes: a flexible substrate having one of two main surfaces on which the conductor is provided; a holding member that holds the other main surface of the flexible substrate so that the end portion of the conductor is farther from the transmission line than the central portion; The wireless communication system of claim 1 further comprising:

4. The transmission line is a ring-shaped transmission line formed on the outer peripheral side surface of a ring-shaped housing.

2. The wireless communication system according to claim 1.

5. the transmission line is a ring-shaped transmission line formed on an inner peripheral side surface of a ring-shaped housing, The conductor has a larger curvature than the ring-shaped transmission line.

2. The wireless communication system according to claim 1.

6. The width of the end portion of the conductor in a direction perpendicular to the extension direction is narrower than the width of the central portion of the conductor in the direction perpendicular to the extension direction.

2. The wireless communication system according to claim 1.

7. The width of the end of the conductor in a direction perpendicular to the extension direction is narrowed from the center of the conductor toward the end.

2. The wireless communication system according to claim 1.

8. A receiving coupler having a conductor that faces a transmission line that transmits a communication signal and receives the communication signal by electromagnetic coupling with the transmission line, wherein an end of the conductor in the extension direction of the transmission line is shaped to be farther away from the transmission line than a center portion of the conductor.

9. a rotating unit having an X-ray tube, an X-ray detector for detecting X-rays emitted from the X-ray tube, and a data acquisition device for acquiring signals of the X-rays detected by the X-ray detector; A fixed part that rotates the rotating part; a transmission line disposed in one of the fixed portion and the rotating portion and configured to transmit a communication signal; a coupler that is disposed on the other of the fixed portion and the rotating portion, that faces the transmission line, that has a conductor that receives the communication signal by electromagnetic coupling with the transmission line, and that has a shape such that an end portion of the conductor in an extension direction of the transmission line is farther from the transmission line than a center portion of the conductor; An X-ray CT apparatus comprising:

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