Receiving device, wireless communication system, and X-ray CT scanner

Abstract

To reduce changes in the characteristic impedance of the transmission line and suppress the occurrence of reception errors. [Solution] The receiving device according to this embodiment comprises a receiving coupler and a shield. The receiving coupler is electromagnetically coupled to the transmission line. The shield protects the receiving coupler from external electromagnetic waves. A coupling suppression region that suppresses capacitive coupling between the transmission line and the shield wall is provided on the wall of the shield facing the transmission line.

Description

Technical Field

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

Background Art

[0002] Wireless communication systems that perform wireless communication using near electromagnetic fields have been developed. For example, in said wireless communication system, wireless communication is performed using a ring-shaped transmission path that transmits transmission data (communication signals) and a coupler (receiving coupler) that receives communication signals through electromagnetic field coupling. When the coupler receives a communication signal from a transmission line, the characteristic impedance of the transmission line changes at the location where the coupler is disposed, and the communication signal reflects at the end of the coupler. If large reflection occurs in the signal received by the coupler, such as multiple reflection of the communication signal at the end of the coupler, this may cause reception errors.

[0003] Accordingly, in a wireless communication system that performs wireless communication via near electromagnetic fields using a transmission line and a coupler, a technology is known that suppresses the occurrence of reception errors by forming the end of the coupler into a narrow shape to reduce reflection of the signal received by the coupler.

[0004] Further, from the perspective of EMC (Electromagnetic Compatibility), a communication device (receiving device) including a coupler that receives communication signals from a transmission line is sometimes covered by a shield case for protecting the coupler from external electromagnetic waves. From the perspective of EMC, in order to prevent noise propagation from the periphery of the receiving device, it is preferable for the wall surface of the shield case to be as close to the transmission line as possible. However, capacitive coupling between the transmission line and the shield case changes the characteristic impedance of the transmission line. As a result, reflection occurs at locations where the characteristic impedance changes, making reception errors more likely to occur.

Prior Art Literature

Patent Literature

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-006523 [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the problems that the embodiments disclosed in this specification and drawings aim to solve is to reduce changes in the characteristic impedance of the transmission line without significantly impairing shielding performance, thereby suppressing the occurrence of reception errors. However, the problems solved by the embodiments disclosed in this specification and 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]

[0007] The receiving device according to this embodiment comprises a receiving coupler and a shield. The receiving coupler is electromagnetically coupled to the transmission line. The shield protects the receiving coupler from external electromagnetic waves. A coupling suppression region, which suppresses capacitive coupling between the transmission line and the shield wall, is provided on the wall of the shield facing the transmission line. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example of the configuration of an X-ray CT apparatus to which the wireless communication system according to this embodiment is applied. [Figure 2] Figure 2 shows an example of the configuration of the wireless communication system according to this embodiment. [Figure 3] Figure 3 is a diagram illustrating the configuration of the wireless communication system shown in Figure 2. [Figure 4] Figure 4 is a diagram illustrating the phenomenon that occurs when the shield case shown in Figure 3 is used. [Figure 5A] Figure 5A shows an example of the configuration of a receiving device in a wireless communication system according to the first embodiment. [Figure 5B]Figure 5B shows an example of the configuration of a receiving device in a wireless communication system according to the first embodiment. [Figure 5C] Figure 5C shows an example of the configuration of a receiving device in a wireless communication system according to the first embodiment. [Figure 6] Figure 6 shows an example of the configuration of a receiving device in a wireless communication system according to the second embodiment. [Figure 7] Figure 7 shows an example of the configuration of a receiving device in a wireless communication system according to a modified example of the second embodiment. [Figure 8] Figure 8 shows an example of the configuration of a receiving device in a wireless communication system according to a modified example of the second embodiment. [Figure 9] Figure 9 shows an example of the configuration of a receiving device in a wireless communication system according to a modified example of the second embodiment. [Figure 10] Figure 10 shows an example of the configuration of a receiving device in a wireless communication system according to the third embodiment. [Figure 11] Figure 11 shows an example of the configuration of a receiving device in a wireless communication system according to a modified example of the third embodiment. [Figure 12] Figure 12 shows an example of the configuration of a receiving device in a wireless communication system according to a modified example of the third embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the receiving device, wireless communication system, and X-ray CT apparatus will be described in detail with reference to the drawings. Here, an embodiment of a wireless communication system equipped with a receiving device will be described as an example. Note that the embodiments are not limited to the embodiments described below. Also, the contents described in one embodiment will, in principle, be applied similarly to other embodiments.

[0010] The wireless communication system according to this embodiment is applied, for example, to an X-ray computed tomography (CT) apparatus.

[0011] FIG. 1 is a diagram showing an example configuration of an X-ray CT apparatus 100 to which the wireless communication system according to the present embodiment is applied. The X-ray CT apparatus 100 acquires CT image data of a subject. Specifically, the X-ray CT apparatus 100 rotationally moves an X-ray tube and an X-ray detector approximately around the subject, detects X-rays transmitted through the subject, and acquires projection data. Then, the X-ray CT apparatus 100 generates CT image data based on the acquired projection data. As shown in FIG. 1, the X-ray CT apparatus 100 includes a gantry device 10, a couch device 30, and a console device 40.

[0012] In the present embodiment, the rotation axis of the rotating frame 13 in the non-tilt state or the longitudinal direction of the top plate 33 of the couch device 30 is defined as the Z-axis direction. An axial direction orthogonal to the Z-axis direction and horizontal with respect to the floor surface is defined as the X-axis direction. An axial direction orthogonal to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. FIG. 1 illustrates the gantry device 10 drawn from a plurality of directions for explanation, and shows a case where the X-ray CT apparatus 100 includes one gantry device 10.

[0013] The gantry device 10 includes 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.

[0014] The X-ray tube 11 is a vacuum tube including a cathode (filament) that generates thermoelectrons and an anode (target) that generates X-rays when bombarded with thermoelectrons. When a high voltage is applied from the X-ray high-voltage device 14, the X-ray tube 11 emits thermoelectrons from the cathode toward the anode, thereby generating X-rays for irradiation onto the subject P. For example, the X-ray tube 11 may be a rotating anode type X-ray tube that generates X-rays by irradiating thermoelectrons onto a rotating anode.

[0015] The wedge 16 is a filter for adjusting the X-ray dose irradiated from the X-ray tube 11. Specifically, the wedge 16 is a filter that transmits and attenuates X-rays irradiated from the X-ray tube 11 such that 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, and is a filter formed by processing a material such as aluminum to have a predetermined target angle and a predetermined thickness.

[0016] The collimator 17 is a lead plate or the like for narrowing down the irradiation range of X-rays that have passed through the wedge 16, and forms a slit by a combination of a plurality of lead plates or the like. Note that the collimator 17 may also be referred to as an X-ray diaphragm. In addition, although FIG. 1 shows a case where the wedge 16 is arranged between the X-ray tube 11 and the collimator 17, the collimator 17 may be arranged between the X-ray tube 11 and the wedge 16. In this case, the wedge 16 transmits and attenuates X-rays irradiated from the X-ray tube 11 whose irradiation range is limited by the collimator 17.

[0017] The X-ray detector 12 includes a plurality of detection elements that detect X-rays. Each detection element in the X-ray detector 12 detects X-rays that are irradiated from the X-ray tube 11 and pass through the subject P, and outputs a signal corresponding to the detected X-ray dose to the DAS 18. For example, the X-ray detector 12 has a plurality of detection element arrays in which a plurality of detection elements are arranged in a channel direction along one arc centered on the focal point of the X-ray tube 11. For example, the X-ray detector 12 has a structure in which a plurality of detection element arrays each having a plurality of detection elements arranged in the channel direction are arranged in a column direction (slice direction, row direction).

[0018] For example, the X-ray detector 12 is an indirect conversion type detector having a grid, a scintillator array, and a photosensor array. The scintillator array has multiple scintillators. The scintillators have scintillator crystals that output light in a quantity of photons corresponding to the amount of incident X-rays. The grid is arranged on the X-ray incident side of the scintillator array and has an X-ray shielding plate that absorbs scattered X-rays. The grid is sometimes called a collimator (one-dimensional collimator or two-dimensional collimator). The photosensor array has the function of converting the amount of light from the scintillators into an electrical signal, and has a photosensor such as a photodiode. The X-ray detector 12 may also be a direct conversion type detector having semiconductor elements that convert incident X-rays into electrical signals.

[0019] The X-ray high-voltage device 14 includes an electrical circuit such as a transformer and a rectifier, a high-voltage generator that generates a high voltage to be applied to the X-ray tube 11, and an X-ray control device that controls the output voltage according to the X-rays generated by the X-ray tube 11. The high-voltage generator may be of the transformer type or the inverter type. The X-ray high-voltage device 14 may be installed on the rotating frame 13 or on the fixed frame 19. Here, the fixed frame 19 is a frame that rotatably supports the rotating frame 13 and has a rotation mechanism for rotating the rotating frame 13. Here, the rotating frame 13 and the fixed frame 19 are examples of the "rotating part" and "fixed part," respectively.

[0020] The DAS18 collects X-ray signals detected by each detection element of the X-ray detector 12. For example, the DAS18 has an amplifier that performs amplification processing on the electrical signals output from each detection element, and an A / D converter that converts the electrical signals into digital signals, thereby generating detection data. The DAS18 is implemented, for example, by a processor. Here, the DAS18 is an example of a "data acquisition device".

[0021] The rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 opposite 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. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 can also support an X-ray high-voltage device 14, a wedge 16, a collimator 17, a DAS 18, etc. Furthermore, the rotating frame 13 can also support various other components not shown in Figure 1.

[0022] Communication devices are provided on both the rotating frame 13 and the fixed frame 19, which is the non-rotating part of the mounting device 10. For example, data generated by the DAS 18 (collected X-ray signals) is transmitted wirelessly from the communication device on the rotating frame 13 to the communication device on the fixed frame 19 and then forwarded to the console device 40. Also, for example, control signals transmitted by the console device 40 to the rotating frame 13 are transmitted wirelessly from the communication device on the fixed frame 19 to the communication device on the rotating frame 13. The communication devices on the rotating frame 13 and the communication devices on the fixed frame 19 constitute a wireless communication system 500, which will be described later.

[0023] The control device 15 includes a processing circuit with a CPU (Central Processing Unit), etc., and a drive mechanism such as a motor and actuator. The control device 15 receives input signals from the input interface 43 and controls the operation of the frame device 10 and the bed device 30. For example, the control device 15 controls the rotation of the rotating frame 13, the tilt of the frame device 10, and the operation of the bed device 30 and the top plate 33. To give one example, as a control to tilt the frame device 10, the control device 15 rotates the rotating frame 13 around an axis parallel to the X-axis direction based on the input tilt angle information. The control device 15 may be installed on the frame device 10 or on the console device 40.

[0024] The patient bed apparatus 30 is a device for placing and moving the subject P to be photographed, and comprises a base 31, a patient bed drive 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 patient bed drive device 32 is a drive mechanism that moves the top plate 33 on which the subject P is placed in the direction of the long axis of the top plate 33, and includes a motor and 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. In addition to moving the top plate 33, the patient bed drive device 32 may also move the support frame 34 in the direction of the long axis of the top plate 33.

[0025] The console device 40 includes a memory 41, a display 42, an input interface 43, and a processing circuit 44. Although the console device 40 is described separately from the mounting device 10, the mounting device 10 may include the console device 40 or some of its components.

[0026] Memory 41 can be implemented using, for example, semiconductor memory elements such as RAM (Random Access Memory) or flash memory, a hard disk, or an optical disc. Memory 41 stores, for example, projection data or CT image data. It can also store, for example, programs for circuits included in the X-ray CT scanner 100 to perform their functions. Alternatively, memory 41 may be implemented using a group of servers (cloud) connected to the X-ray CT scanner 100 via a network.

[0027] The display 42 displays various types of information. For example, the display 42 may display various images generated by the processing circuit 44, or it may display a GUI (Graphical User Interface) to receive various operations from the operator. For example, the display 42 may be a liquid crystal display or a CRT (Cathode Ray Tube) display. The display 42 may also be mounted on the stand device 10. Furthermore, the display 42 may be a desktop type, or it may be composed of a tablet terminal or the like that can communicate wirelessly with the console device 40.

[0028] The input interface 43 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs them to the processing circuit 44. For example, the input interface 43 receives input operations from the operator such as reconstruction conditions when reconstructing CT image data, and image processing conditions when generating post-processed images from CT image data. For example, the input interface 43 can be implemented by a mouse, keyboard, trackball, switch, button, joystick, touchpad that performs input operations by touching the operating surface, touchscreen that integrates a display screen and a touchpad, non-contact input circuit using an optical sensor, audio input circuit, etc. The input interface 43 may also be provided on the mounting device 10. Furthermore, the input interface 43 may consist of the console device 40 main unit and a tablet terminal that can communicate wirelessly. In addition, the input interface 43 is not limited to those equipped with physical operating components such as a mouse or keyboard. For example, an electrical signal processing circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the console device 40 and outputs these electrical signals to the processing circuit 44 is also included as an example of the input interface 43.

[0029] The processing circuit 44 controls the operation of the entire X-ray CT apparatus 100. For example, the processing circuit 44 performs system control functions 440, scan control functions 441, preprocessing functions 442, reconstruction processing functions 443, and display control functions 444.

[0030] The system control function 440 controls various functions of the processing circuit 44 based on input operations received from the operator via the input interface 43.

[0031] The scan control function 441 performs an X-ray scan on the subject P. For example, the scan control function 441 controls the scan based on input operations received from the operator via the input interface 43. Specifically, the scan control function 441 controls the output voltage from the high-voltage generator by sending a control signal to the X-ray high-voltage device 14 based on the input operation. The scan control function 441 also controls data acquisition by the DAS 18 by sending a control signal to the DAS 18.

[0032] The preprocessing function 442 generates preprocessed data by performing preprocessing on the X-ray detection data transmitted from the DAS18. Specifically, the preprocessing function 442 generates preprocessed data by performing correction processes such as logarithmic transformation, offset correction, sensitivity correction, and beam hardening correction. Note that the data before preprocessing (X-ray detection data) and the data after preprocessing are sometimes collectively referred to as projection data.

[0033] The reconstruction processing function 443 generates CT image data by reconstructing the projection data generated by the preprocessing function 442 using various reconstruction methods (for example, back projection methods such as FBP (Filtered Back Projection) and iterative approximation methods). The reconstruction processing function 443 also stores the generated CT image data in the memory 41.

[0034] The display control function 444 displays various images generated by the processing circuit 44 on the display 42. For example, the display control function 444 displays CT image data generated by the reconstruction processing function 443 on the display 42.

[0035] In the X-ray CT scanner 100 shown in Figure 1, each processing function is stored in memory 41 in the form of a program that can be executed by a computer. The processing circuit 44 is a processor that realizes the function corresponding to each program by reading and executing the program from memory 41. In other words, the processing circuit 44, when it has read a program, has the function corresponding to the read program.

[0036] In the above description, the term "processor" refers to circuits such as CPUs (Central Processing Units), GPUs (Graphics Processing Units), and Application Specific Integrated Circuits (ASICs). It also refers to circuits such as programmable logic devices. Examples of programmable logic devices include Simple Programmable Logic Devices (SPLDs) and Complex Programmable Logic Devices (CPLDs). Another example of a programmable logic device is a Field Programmable Gate Array (FPGA). When the processor is a CPU, it functions by reading and executing a program stored in memory 41. On the other hand, when the processor is an ASIC, instead of storing the program in memory 41, the program is directly embedded within the processor's circuitry. Note that each processor in this embodiment is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor, and its functions may be realized through this configuration. Furthermore, the multiple components shown in Figure 1 may be integrated into a single processor to realize their functions.

[0037] 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.

[0038] Figure 2 shows an example of the configuration of the wireless communication system 500 according to this embodiment.

[0039] As shown in Figure 2, the wireless communication system 500 comprises a rotating communication device 600, a ring-shaped transmission line 700, and a stationary communication device 800. In the example shown in Figure 2, the communication device 600 and the ring-shaped transmission line 700 are located on the rotating part (rotating frame 13), and the communication device 800 is located on the stationary part (stationary frame 19). The communication devices 600 and 800 communicate via the ring-shaped transmission line 700. In the example shown in Figure 2, the rotation direction of the rotating part, the rotating communication device 600, and the ring-shaped transmission line 700 is clockwise.

[0040] The ring-shaped transmission path 700 has multiple transmission paths (hereinafter referred to as segments) for transmitting transmission data (communication signals). In the example shown in Figure 2, the ring-shaped transmission path 700 is divided into two segments (hereinafter referred to as the first segment 701 and the second segment 702) at 180° intervals. For example, the ring-shaped transmission path 700 is divided into the second segment 702, which transmits the communication signal in the direction of rotation of the rotating part, and the first segment 701, which transmits the communication signal in the direction opposite to the direction of rotation.

[0041] The rotating communication device 600 includes a rotating communication unit 610 that transmits transmission data (communication signals) including a transmission signal and a clock signal, a signal input unit 620 for inputting signals (communication signals) to the input ends of each transmission line (first segment 701, second segment 702), and a signal termination unit 630 for preventing reflection of the signals at the ends of each transmission line. The signal input unit 620 is connected to the input end of each transmission line, and the signal termination unit 630 is connected to the end of each transmission line. For example, in Figure 2, each transmission line (first segment 701, second segment 702) is bent from the circumferential direction to the radial direction of the ring-shaped metal part, which is a reference potential conductor. The signal input unit 620 is located in the bent region as the input end of each transmission line, and the signal termination unit 630 is located in the bent region as the end of each transmission line. Here, the communication device 600 is an example of a "transmitting device".

[0042] The rotating communication unit 610 has an 8B10B conversion unit that performs clock signal recovery (restoration, repair) and encoding for DC balance assurance on the transmitted data (communication signals). The signal input unit 620 has a differential driver and a distributor for inputting the transmitted data to each segment. Note that the encoding method is not limited to 8B10B; other methods such as 64B66B or 128B130B may also be used.

[0043] The fixed-side communication device 800 includes a coupler 810, which is an antenna coupler, and a fixed communication unit 820. The coupler 810 receives communication signals flowing through the ring-shaped transmission path 700 by electromagnetic field coupling. The coupler 810 receives communication signals from one of the segments, the first segment 701 and the second segment 702. The fixed communication unit 820 recovers (restores, repairs) the clock signal according to the reception position where the coupler 810 receives the communication signal from one of the segments. Then, the fixed communication unit 820 generates received data (communication signals) based on the transmission signals included in the communication signals received by the coupler 810 and the recovered clock signal. Here, the communication device 800 is an example of a "receiving device".

[0044] In the example shown in Figure 2, when the communication device 600 and the ring-shaped transmission path 700 are located in the rotating part and the communication device 800 is located in the fixed part, the transmitted data (communication signal) is the X-ray signal (X-ray detection data) collected by the data acquisition device (DAS18). In this case, the fixed-side communication device 800 recovers the clock signal included in the transmitted data and generates received data (communication signal) based on the transmitted data and the recovered clock signal. For example, in the processing circuit 44 of the console device 40, the preprocessing function 442 preprocesses the received 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 preprocessing function 442.

[0045] Figure 3 is a diagram illustrating the configuration of the wireless communication system 500 shown in Figure 2.

[0046] As shown in Figure 3, the signal input section 620 of the rotating communication device 600 is configured with a differential transmission buffer and outputs the transmission data (communication signals) SIG+ and SIG- input from the rotating communication unit 610 to the ring-shaped transmission path 700.

[0047] The ring-shaped transmission line 700 has the above-mentioned plurality of transmission lines (in the example shown in Figure 2, the first segment 701 and the second segment 702), and each transmission line has transmission lines 711 and 712 that constitute the differential transmission line 710, and a reference potential conductor 720 (GND). The transmission lines 711 and 712 are provided in the circumferential direction of the ring-shaped metal part which is the reference potential conductor 720. The transmission lines 711 and 712 are arranged in the axial direction of the ring-shaped metal part and transmit the communication signals SIG+ and SIG-, respectively. The communication signals SIG+ and SIG- are differential signals transmitted over the differential transmission line 710. Here, the transmission lines 711 and 712 are examples of "transmission lines".

[0048] 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 this embodiment is not limited to this. For example, the differential transmission line 710 of each transmission line in the ring-shaped transmission line 700 may be other differential transmission lines such as a differential coplanar line or a grounded differential coplanar line. Alternatively, the differential transmission line 710 may be constructed using transmission lines patterned on a flexible substrate, and the ring-shaped transmission line 700 may be constructed using the differential transmission line 710 and a metal member (ring-shaped metal part) that serves as a reference potential conductor 720.

[0049] In the communication device 800, the coupler 810 is provided with respect to the differential transmission line 710. For example, the coupler 810 faces the transmission lines 711 and 712 that constitute the differential transmission line 710, and receives communication signals SIG+ and SIG- through electromagnetic field coupling with the transmission lines 711 and 712. In the example shown in Figure 3, the coupler 810 receives communication signals SIG+ and SIG- from the transmission lines 711 and 712 that constitute the differential transmission line 710 of one of the segments (first segment 701) of the first segment 701 and second segment 702 of the ring-shaped transmission line 700, respectively. Here, the coupler 810 is an example of a "coupler" or "receiving coupler".

[0050] The coupler 810 of the communication device 800 has two electrode conductors 811 and a flexible substrate 812 on which the two electrode conductors 811 are formed. Note that the flexible substrate 812 shown in Figure 4 is omitted in Figure 3. The two electrode conductors 811 each face the transmission lines 711 and 712, and receive the communication signals SIG+ and SIG- through electromagnetic field coupling with the transmission lines 711 and 712.

[0051] As shown in Figure 3, the fixed communication unit 820 of the communication device 800 includes a waveform shaping unit 821 such as a comparator, a clock signal recovery unit 822, a generation unit 823, and a shield case 1830. In Figure 3, the fixed communication unit 820 is shown through the wall surface of the shield case 1830 to illustrate the various components of the fixed communication unit 820.

[0052] The waveform shaping unit 821 amplifies the communication signal received by the coupler 810. The clock signal recovery unit 822 recovers (restores, repairs) 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 the coupler 810 and the clock signal recovered by the clock signal recovery unit 822. For example, the generation unit 823 generates received data by performing decoding such as 10B8B conversion according to the encoding performed by the rotating communication unit 610. Note that other encoding and decoding methods may be used.

[0053] The shielding case 1830 is a case for protecting the coupler 810 from external electromagnetic waves. For example, from an EMC (Electromagnetic Compatibility) perspective, the coupler 810 and the fixed communication unit 820 of the communication device 800 are covered by the shielding case 1830. Here, from an EMC perspective, in order to prevent the propagation of noise from the surroundings of the communication device 800, it is better if the walls of the shielding case 1830 are as close as possible to the transmission lines 711 and 712.

[0054] The shield case 1830 is also provided with a connector (not shown) for, for example, transmitting received data generated by the communication device 800 to the console device 40 via a transmission cable.

[0055] Figure 4 is a diagram illustrating the phenomenon when the shield case 1830 shown in Figure 3 is used. Note that, similar to Figure 3, Figure 4 shows the fixed communication unit 820 from Figure 3, visible through the wall surface of the shield case 1830. In Figure 4, the clock signal recovery unit 822 and generation unit 823 from Figure 3 are omitted. Also, the connectors provided on the shield case 1830 are omitted in Figure 4.

[0056] It is desirable that communication signals on transmission lines 711 and 712 be transmitted to the communication device 800 without reflection. In other words, it is desirable that the characteristic impedance of transmission lines 711 and 712 remain constant. However, capacitive coupling between transmission lines 711 and 712 and the shield case 1830 causes the characteristic impedance of transmission lines 711 and 712 to change. For example, in Figure 4, capacitive coupling between transmission lines 711 and 712 and the wall surface of the shield case 1830 that faces transmission lines 711 and 712 causes the characteristic impedance of transmission lines 711 and 712 to change. As a result, reflection occurs at locations where the characteristic impedance changes, making reception errors more likely.

[0057] Therefore, the receiving device (communication device 800) of the wireless communication system 500 according to this embodiment includes a coupler 810 that electromagnetically couples with the transmission lines 711 and 712, and a shielding case that protects the coupler 810 from external electromagnetic waves. In this embodiment, a coupling suppression region that suppresses capacitive coupling between the transmission lines 711 and 712 and the wall surface of the shielding case is provided on the wall surface of the shielding case that faces the transmission lines 711 and 712. As a result, in this embodiment, since the coupling suppression region is provided on the wall surface of the shielding case that faces the transmission lines 711 and 712 in the communication device 800, it is possible to reduce changes in the characteristic impedance of the transmission lines and suppress the occurrence of reception errors.

[0058] (First Embodiment) In the first embodiment, the coupling suppression region is provided at the lower part of the wall surface facing the transmission lines 711 and 712. Specifically, in the first embodiment, at least one opening is formed as the coupling suppression region at the lower part of the wall surface facing the transmission lines 711 and 712. More specifically, in the first embodiment, one opening is formed as the coupling suppression region.

[0059] Figures 5A to 5C show an example of the configuration of a receiving device (communication device 800) of a wireless communication system 500 according to the first embodiment. Note that in Figure 5A, the clock signal recovery unit 822 and generation unit 823 shown in Figure 3 are omitted, and in Figures 5B and 5C, the coupler 810 and fixed communication unit 820 (waveform shaping unit 821, clock signal recovery unit 822, generation unit 823) shown in Figure 3 are omitted. Also, in Figures 5B and 5C, the wall surface where the coupling suppression region is formed in the shield case is mainly shown.

[0060] As shown in Figures 5A to 5C, in the first embodiment, the communication device 800 is equipped with a shield case 830 instead of the shield case 1830 in Figure 3. The shield case 830 is a case for protecting the coupler 810 from external electromagnetic waves. For example, the coupler 810 and the fixed communication unit 820 of the communication device 800 are covered by the shield case 830. Here, the shield case 830 is an example of a "shield".

[0061] The shield case 830 is also provided with a connector (not shown) for, for example, transmitting received data generated by the communication device 800 to the console device 40 via a transmission cable.

[0062] As shown in Figures 5A to 5C, the shield case 830 consists of one top surface 831 and four wall surfaces 832 to 835 connected to the top surface 831, which constitute the shield.

[0063] Wall surfaces 832 and 833 are walls aligned with the direction of extension of the transmission lines 711 and 712, and are not facing the transmission lines 711 and 712, but are facing each other. Wall surfaces 834 and 835 are walls aligned with a direction that intersects (is perpendicular to) the direction of extension of the transmission lines 711 and 712, and are facing the transmission lines 711 and 712, and are facing each other. Here, the direction of extension of the transmission lines 711 and 712 corresponds to the circumferential direction of the ring-shaped metal part which is the reference potential conductor 720 (GND), and the direction that intersects (is perpendicular to) the direction of extension of the transmission lines 711 and 712 corresponds to the axial direction of the ring-shaped metal part.

[0064] Of the walls 832 to 835 of the shield case 830, wall surfaces 834 and 835 facing the transmission lines 711 and 712 are provided with coupling suppression regions 900 to suppress capacitive coupling between the transmission lines 711 and 712 and the walls of the shield case 830. For example, the coupling suppression regions 900 are provided at the lower part of wall surfaces 834 and 835. Specifically, the coupling suppression regions 900 are areas including openings formed at the lower part of wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712. Although Figures 5B and 5C illustrate wall surface 834 with an opening, wall surface 835 also has a similar opening. Furthermore, the lower part of the wall surfaces 834 and 835 is the part that is radially close to the transmission lines 711 and 712. For example, if the coupler 810 is located on the inner circumference of the ring-shaped transmission line 700 as shown in Figure 2, then it is the radially outer part of the wall surfaces 834 and 835.

[0065] For example, in the coupling suppression region 900, the width of the opening (axial length) is formed considering the width of the transmission lines 711 and 712, the distance between transmission lines 711 and 712, and a slight displacement between the shield case 830 and the transmission lines 711 and 712 during rotation.

[0066] In this first embodiment, by forming an opening as a coupling suppression region 900, the distance between the transmission lines 711 and 712 and the shield case 830 can be increased, and the capacitive coupling C between the transmission lines 711 and 712 and the wall surface of the shield case 830 can be suppressed.

[0067] For example, in Figures 5A and 5B, let "d" be the distance between the transmission lines 711 and 712 and the upper end of the wall surface 834 where the coupling suppression region 900 of the shield case 830 is provided. Let "C" be the capacitive coupling between the transmission lines 711 and 712 and the wall surface 834, let "S" be the area between the transmission lines 711 and 712 and the wall surface 834, and let ε be the dielectric constant. In this case, the capacitive coupling C between the transmission lines 711 and 712 and the wall surface 834 is calculated as C = ε × S / d. Similarly to the case of wall surface 834, the capacitive coupling C between the transmission lines 711 and 712 and the wall surface 835 is calculated as C = ε × S / d.

[0068] Therefore, in the first embodiment, by forming an opening as a coupling suppression region 900, the distance d between the transmission lines 711 and 712 and the shield case 830 can be increased, and the capacitive coupling C between the transmission lines 711 and 712 and the wall surface of the shield case 830 can be suppressed.

[0069] For example, the distance d between the transmission lines 711 and 712 and the upper ends of the wall surfaces 834 and 835, where the coupling suppression region 900 of the shield case 830 is provided, in Figures 5A and 5B is sufficiently longer than the distance between the transmission lines 711 and 712 and the wall surface of the shield case 1830 in Figures 3 and 4. In this case, according to C = ε × S / d, the capacitive coupling C between the transmission lines 711 and 712 and the wall surface of the shield case 830 is reduced compared to the capacitive coupling between the transmission lines 711 and 712 and the wall surface of the shield case 1830. That is, in the first embodiment, the capacitive coupling C can be suppressed by reducing the average value of S / d along the axial direction.

[0070] As a result, in the first embodiment, it is possible to reduce the change in the characteristic impedance of the differential transmission lines 710 (transmission lines 711, 712) of the ring-shaped transmission line 700 and suppress the occurrence of reception errors.

[0071] (Second Embodiment) In the first embodiment, a case was described in which one large opening is formed as a coupling suppression region 900 in the lower part of the wall surfaces 834 and 835 facing the transmission lines 711 and 712 of the shield case 830. In the second embodiment, a case is described in which multiple openings are formed as coupling suppression regions 900 in the lower part of the wall surfaces 834 and 835.

[0072] Figure 6 shows an example of the configuration of a receiving device (communication device 800) of the wireless communication system 500 according to the second embodiment. Note that in Figure 6, the fixed communication unit 820 (waveform shaping unit 821, clock signal recovery unit 822, generation unit 823) shown in Figure 3 is omitted. Also, in Figure 6, the connector provided on the shield case 830 is omitted. Furthermore, in Figure 6, the wall surface 834 (835) where the coupling suppression region 900 is formed in the shield case 830 is mainly shown.

[0073] For example, in Figure 6, the lower parts of the wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712 are formed in a rectangular wave shape. For example, a rectangular wave-shaped opening is formed in the region from the upper end to the lower end of the coupling suppression region 900. Specifically, the coupling suppression region 900 is a region that includes the rectangular wave-shaped portion 910 formed in the lower part of the wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712, and the openings between adjacent rectangular waves of the rectangular wave-shaped portion 910. Although Figure 6 shows the wall surface 834 with the rectangular wave-shaped opening formed therein, the wall surface 835 also has a similar opening formed therein.

[0074] Here, as in the first embodiment, increasing the aperture area reduces the change in the characteristic impedance of the transmission lines 711 and 712, but the shielding performance deteriorates from an EMC standpoint.

[0075] Therefore, in the second embodiment, rectangular wave-shaped openings are provided as coupling suppression regions 900 on the wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712. By reducing the area of ​​the openings on the wall surfaces 834 and 835 and decreasing the average value of S / d along the axial direction, it is possible to suppress the capacitive coupling C between the transmission lines 711 and 712 and the wall surface of the shield case 830 while maintaining shielding performance.

[0076] As a result, in the second embodiment, it is possible to reduce the change in the characteristic impedance of the transmission lines 711 and 712 without significantly impairing the shielding performance, thereby suppressing the occurrence of reception errors.

[0077] (modified version) Figures 7 to 9 show an example of the configuration of a receiving device (communication device 800) of a wireless communication system 500 according to a modified example of the second embodiment. Note that in Figures 7 to 9, the fixed communication unit 820 (waveform shaping unit 821, clock signal recovery unit 822, generation unit 823) shown in Figure 3 is omitted. Also, in Figures 7 to 9, the connector provided on the shield case 830 is omitted. Furthermore, in Figures 7 to 9, the wall surface 834 (835) where the coupling suppression region 900 is formed in the shield case 830 is mainly shown.

[0078] In the example shown in Figure 7, the lower parts of the walls 834 and 835 of the shield case 830 facing the transmission lines 711 and 712 are formed in a triangular wave shape. For example, triangular wave-shaped openings are formed in the region from the upper end to the lower end of the coupling suppression region 900. Specifically, the coupling suppression region 900 is a region that includes the triangular wave portion 920 formed in the lower part of the walls 834 and 835 of the shield case 830 facing the transmission lines 711 and 712, and the openings between adjacent triangular waves of the triangular wave portion 920.

[0079] Furthermore, in the example shown in Figure 8, the lower end of the triangular corrugated portion 920 is formed in a rounded shape. For example, the lower end of the triangular corrugated portion 920 is given an R-shaped finish.

[0080] In the example shown in Figure 7, the shield case 830 has a structure that makes it easy to manufacture, and in the example shown in Figure 8, the shield case 830 is given a rounded edge, which improves safety, such as preventing injuries to workers when installing the shield case 830. Note that Figures 7 and 8 show a wall surface 834 with a triangular wave-shaped opening, but the wall surface 835 also has a similar opening.

[0081] Furthermore, in the example shown in Figure 9, the lower parts of the walls 834 and 835 facing the transmission lines 711 and 712 of the shield case 830 are formed in a mesh-like structure. For example, mesh-like openings are formed in the region from the upper end to the lower end of the coupling suppression region 900. Specifically, the coupling suppression region 900 is a region that includes the mesh-like portion 930 formed in the lower parts of the walls 834 and 835 facing the transmission lines 711 and 712 of the shield case 830, and the openings formed in the mesh-like portion 930. Note that although Figure 9 shows the wall 834 with the mesh-like openings formed therein, the wall 835 also has similar openings.

[0082] Thus, in the modified version of the second embodiment, triangular wave-shaped openings or mesh-shaped openings are provided as coupling suppression regions 900 on the wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712. By reducing the area of ​​the openings on the wall surfaces 834 and 835 and decreasing the average value of S / d along the axial direction, it is possible to suppress the capacitive coupling C between the transmission lines 711 and 712 and the wall surface of the shield case 830 while maintaining shielding performance.

[0083] As a result, even in the modified version of the second embodiment, it is possible to reduce the change in the characteristic impedance of the transmission lines 711 and 712 without significantly impairing the shielding performance, thereby suppressing the occurrence of reception errors.

[0084] (Third embodiment) In the first and second embodiments, the case in which at least one opening is formed as a coupling suppression region 900 in the lower part of the wall surface of the shield case 830 facing the transmission lines 711 and 712 was described as an example, but the embodiment is not limited thereto.

[0085] In the third embodiment, the configuration shown in Figure 10 reduces the aperture area compared to the first embodiment, thereby reducing the change in characteristic impedance without significantly impairing shielding performance.

[0086] Figure 10 shows an example of the configuration of a receiving device (communication device 800) of a wireless communication system 500 according to the third embodiment. Note that in Figure 10, the coupler 810, fixed communication unit 820 (waveform shaping unit 821, clock signal recovery unit 822, generation unit 823), and reference potential conductor 720 (GND) shown in Figure 3 are omitted. Also, in Figure 10, the connector provided on the shield case 830 is omitted. Furthermore, in Figure 10, the wall surface 834 (835) where the coupling suppression region 900 is formed in the shield case 830 is mainly shown.

[0087] For example, in Figure 10, the walls 834 and 835 of the shield case 830 facing the transmission lines 711 and 712 have a coupling suppression region 900 in which the thickness in the direction of extension of the transmission lines 711 and 712 (travel direction, signal transmission direction) decreases as it approaches the transmission lines 711 and 712. In the example shown in Figure 10, the walls 834 and 835 are tapered only at the bottom. Note that although Figure 10 shows the wall 834 with a tapered region formed only at the bottom, the wall 835 also has a similar region formed therein.

[0088] Thus, in the third embodiment, by tapering the lower part of the wall surfaces 834 and 835 of the shield case 830 that face the transmission lines 711 and 712, the average value of S / d along the axial direction is reduced, thereby suppressing the capacitive coupling C between the transmission lines 711 and 712 and the wall surfaces of the shield case 830 while maintaining shielding performance.

[0089] As a result, in the third embodiment, it is possible to reduce the change in the characteristic impedance of the transmission lines 711 and 712 without significantly impairing the shielding performance, thereby suppressing the occurrence of reception errors.

[0090] In the example shown in Figure 10, the wall surface of the shield 830 facing the transmission lines 711 and 712 is tapered only at the bottom, but the example is not limited to this, and the wall surface of the shield 830 facing the transmission lines 711 and 712 may be tapered from the top.

[0091] (modified version) Figure 11 shows an example of the configuration of a receiving device (communication device 800) of a wireless communication system 500 according to a modified example of the third embodiment. Note that in Figure 11, the coupler 810, fixed communication unit 820 (waveform shaping unit 821, clock signal recovery unit 822, generation unit 823), and reference potential conductor 720 (GND) shown in Figure 3 are omitted. Also, in Figure 11, the connector provided on the shield case 830 is omitted. Furthermore, in Figure 11, the wall surface 834 (835) where the coupling suppression region 900 is formed in the shield case 830 is mainly shown.

[0092] For example, in Figure 11, the wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712 have recessed areas in the direction of extension (travel direction, signal transmission direction) of the transmission lines 711 and 712, which serve as coupling suppression regions 900. Although Figure 11 shows wall surface 834 with the recessed area formed therein, wall surface 835 also has a similar area formed therein.

[0093] Thus, in this modified version of the third embodiment, the wall surfaces 834 and 835 of the shield case 830 facing the transmission lines 711 and 712 are recessed in the direction of extension of the transmission lines 711 and 712, thereby reducing the average value of S / d along the axial direction. This makes it possible to suppress the capacitive coupling C between the transmission lines 711 and 712 and the wall surface of the shield case 830 while maintaining shielding performance.

[0094] As a result, even in the modified version of the third embodiment, it is possible to reduce the change in the characteristic impedance of the transmission lines 711 and 712 without significantly impairing the shielding performance, thereby suppressing the occurrence of reception errors.

[0095] In the third embodiment, the configurations of the first and second embodiments may be combined.

[0096] For example, in the configuration shown in Figure 11, a large opening is formed in the direction of extension of the transmission lines 711 and 712. However, to improve shielding performance, it is desirable to reduce the size of the opening. For example, to reduce the size of the opening, suppose the walls 834 and 835 of the shield 830 facing the transmission lines 711 and 712 are formed in an uneven shape in the direction of extension of the transmission lines, as shown in Figure 12. However, in the configuration shown in Figure 12, the characteristic impedance of the transmission lines 711 and 712 may change due to capacitive coupling between the transmission lines 711 and 712 and the walls of the shield case 830.

[0097] Therefore, in the configuration shown in Figure 12, for example, it may be combined with any of the configurations shown in Figures 6 to 9 as the configuration of the second embodiment. In this case, for example, in the configuration shown in Figure 12, a plurality of openings are formed in the lower part of the wall surfaces 834 and 835.

[0098] Thus, in the third embodiment, by combining it with the configurations of the first and second embodiments, it is possible to reduce the change in the characteristic impedance of the transmission lines 711 and 712, thereby suppressing the occurrence of reception errors and improving shielding performance.

[0099] (Other embodiments) While embodiments have been described above, various other forms may also be used.

[0100] For example, in the embodiment described above, the communication device 600 and the ring-shaped transmission path 700 are arranged in a rotating part (rotating frame 13), the communication device 800 is arranged in a fixed part (fixed frame 19), and the transmission data (communication signal) is an X-ray signal collected by a data acquisition device (DAS 18). However, the embodiment is not limited to this example.

[0101] For example, if the communication device 600 and the ring-shaped transmission path 700 are located in the fixed part and the communication device 800 is located in the rotating part, the transmitted data (communication signal) is a control signal sent to the rotating part by the console device 40 of the X-ray CT apparatus 100.

[0102] Furthermore, in the above-described embodiment, a wireless communication system 500 comprising a ring-shaped transmission line 700, which is a transmission line 711, 712, and the above-described coupler 810 was described as an example of an X-ray CT apparatus 100, but the invention is not limited to this. For example, the transmission line does not need to be ring-shaped, and the same can be applied to a wireless communication system comprising a planar transmission line and the above-described coupler 810 in this embodiment.

[0103] It should be noted that the components of each device illustrated in this embodiment are functional concepts and do not necessarily need to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions. Furthermore, all or any part of the processing functions performed by each device can be realized by a CPU and a program that is analyzed and executed by the CPU, or by hardware using wired logic.

[0104] Furthermore, the method described in this embodiment can be implemented by executing a pre-prepared program on a computer such as a personal computer or workstation. This program can be distributed via a network such as the Internet. Alternatively, this program can be recorded on a computer-readable non-temporary recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD, and executed by reading it from the recording medium by a computer.

[0105] According to at least one embodiment described above, it is possible to reduce changes in the characteristic impedance of the transmission line and suppress the occurrence of reception errors.

[0106] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of 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 variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0107] 500 Wireless Communication Systems 710 Differential transmission line 711 Transmission line 712 Transmission line 800 Communication equipment 810 Coupler (Receiver Coupler) 830 Shield 900 Binding inhibition region

Claims

1. A receiving coupler that electromagnetically couples with the transmission line, A shield to protect the receiving coupler from external electromagnetic waves, Equipped with, A coupling suppression region is provided on the wall surface of the shield that faces the transmission line, thereby suppressing capacitive coupling between the transmission line and the shield wall surface. Receiving device.

2. The coupling suppression region is provided at the lower part of the wall surface of the shield facing the transmission line. The receiving device according to claim 1.

3. The coupling suppression region is a region that includes at least one opening formed in the lower part of the wall surface of the shield facing the transmission line. The receiving device according to claim 2.

4. The coupling suppression region is a region that includes a rectangular corrugated portion formed on the lower part of the wall surface of the shield facing the transmission line, and an opening between adjacent rectangular waves of the rectangular corrugated portion. The receiving device according to claim 3.

5. The coupling suppression region is a region that includes a triangular wave-shaped portion formed on the lower part of the wall surface of the shield facing the transmission line, and an opening between adjacent triangular waves of the triangular wave-shaped portion. The receiving device according to claim 3.

6. The lower end of the aforementioned triangular wavy portion is formed in a rounded shape. The receiving device according to claim 5.

7. The coupling suppression region includes a mesh-like portion formed on the lower part of the wall surface of the shield facing the transmission line, and an opening formed in the mesh-like portion. The receiving device according to claim 3.

8. The wall surface of the shield facing the transmission line has, as the coupling suppression region, a region in which the thickness in the direction of extension of the transmission line decreases as it approaches the transmission line. The receiving device according to claim 1.

9. The wall surface of the shield facing the transmission line has a recessed region in the direction of extension of the transmission line, which serves as the coupling suppression region. The receiving device according to claim 1.

10. A transmitting device that transmits communication signals, A transmission line for transmitting the aforementioned communication signal, A receiving device having a receiving coupler that electromagnetically couples with the transmission line, and a shield that protects the receiving coupler from external electromagnetic waves, Equipped with, A coupling suppression region is provided on the wall surface of the shield that faces the transmission line, thereby suppressing capacitive coupling between the transmission line and the shield wall surface. Wireless communication system.

11. A rotating unit having an X-ray tube, an X-ray detector for detecting X-rays irradiated from the X-ray tube, and a data acquisition device for collecting the X-ray signals detected by the X-ray detector, A fixing part that rotates the aforementioned rotating part, A transmitting device that transmits communication signals, A transmission line for transmitting the communication signal is arranged in one of the fixed part and the rotating part, A receiving device comprising a receiving coupler disposed on the other side of the fixed part and the rotating part and electromagnetically coupled with the transmission line, and a shield that protects the receiving coupler from external electromagnetic waves, Equipped with, A coupling suppression region is provided on the wall surface of the shield that faces the transmission line, thereby suppressing capacitive coupling between the transmission line and the shield wall surface. X-ray CT device.

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