Wireless communication system, x-ray ct apparatus, and communication control method

Abstract

To perform stable communication between a rotating part and a fixed part when simultaneously performing data communication by a plurality of channels.SOLUTION: A wireless communication system according to the present embodiment includes a reception-side communication device, a transmission-side communication device, and a switching unit. In the reception-side communication device, a plurality of reception media are arranged apart from each other along a circumferential direction in one of a fixed part and a rotating part, and signals of a plurality of channels are received. In the transmission-side communication device, a plurality of transmission media, the number of which is larger than the number of channels, are arranged at intervals in a circumferential direction in the other of the fixed portion and the rotating portion, and signals of the plurality of channels are transmitted. The switching unit allocates signals of the plurality of channels in which data is divided to respective transmission media. With regard to two transmission media respectively facing two reception media adjacent in the circumferential direction, the switching unit stops or relatively attenuates a signal outputted to one of the two transmission media.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Communication systems that use electromagnetic coupling to perform wireless communication within or between nearby devices are known. For example, wireless transmission in rotating, movable parts of robotic hands and network cameras can reduce cable wear and enable free rotation. Meanwhile, the amount of image data acquired by cameras and other devices installed on the rotating parts that must be transmitted is becoming enormous to meet demands for higher resolution. A communication data mechanism that can transfer this large amount of communication data without increasing the mounting space is known.

[0003] The above-described data communication mechanism discloses a configuration in which data is divided into multiple channels and output to multiple transmission media (long-length transmitting couplers) spaced apart along the circumference of the rotating part, and the data is received by multiple receiving media (short-length receiving couplers) corresponding to the multiple channels arranged in the fixed part. In this case, multiple channels can be communicated simultaneously in the rotating part, enabling stable communication between the rotating part and the fixed part without increasing the mechanical thickness or transmission speed. The above-described data communication mechanism uses a long-length coupler (long-length transmitting) on ​​the transmitting side and a short-length coupler (short-length receiving) on ​​the receiving side. However, if a similar configuration were used for data transmission from the fixed part to the rotating part, a long-length transmitting coupler would also be required on the fixed part, leaving room for further improvement in order to reduce the device's size. Therefore, a configuration using a short-length coupler (short-length transmitting) on ​​the transmitting side and a long-length coupler (long-length receiving) on ​​the receiving side is desired to enable stable communication between the rotating part and the fixed part. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5121236 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 achieve stable communication between a rotating part and a fixed part when performing data communication simultaneously over multiple channels. 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 below can also be positioned as other problems. [Means for solving the problem]

[0006] The wireless communication system according to this embodiment includes a signal generating unit, a receiving communication device, a transmitting communication device, and a switching unit. The signal generating unit divides data and outputs signals of multiple channels. The receiving communication device receives signals of the multiple channels from one of a fixed unit and a rotating unit, where multiple receiving media are spaced apart in the circumferential direction. The transmitting communication device transmits signals of the multiple channels from the other of a fixed unit and a rotating unit, where multiple transmission media are spaced apart in the circumferential direction and the number of transmission media is greater than the number of channels. The switching unit assigns the signals of the multiple channels output from the signal generating unit to each transmission medium. When one of the multiple transmission media passes near a gap between two circumferentially adjacent receiving media, the switching unit switches the signals transmitted from the transmission medium to the two receiving media to signals of the same channel. For two transmission media facing two circumferentially adjacent receiving media, the switching unit stops or relatively attenuates the signals output to one of the two transmission media. [Brief explanation 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 wireless communication system according to this embodiment is applied. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of a wireless communication system according to this embodiment. [Figure 3A] FIG. 3A is a diagram illustrating an example of the configuration of a wireless communication system according to the first embodiment. [Figure 3B] FIG. 3B is a diagram illustrating an example of a 2-channel receiving communication device obtained by dividing the receiving side into two, as a receiving communication device of the wireless communication system according to the first embodiment. [Figure 4A] FIG. 4A is a diagram illustrating an example of a received waveform in the wireless communication system according to the first embodiment. [Figure 4B] FIG. 4B is a diagram illustrating an example of a received waveform in the wireless communication system according to the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of the wireless communication system according to the first embodiment when rotating. [Figure 6] FIG. 6 is a diagram showing the relationship between the rotation angle and the output of the transmission signal in the wireless communication system according to the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of the configuration of a wireless communication system according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing the relationship between the rotation angle and the output of the transmission signal in the wireless communication system according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing a specific example in which the communication system according to this embodiment is applied to an X-ray CT apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of a wireless communication system, an X-ray CT apparatus, and a communication control method will be described in detail with reference to the drawings. Note that the embodiments are not limited to the following embodiments. Furthermore, the content described in one embodiment is, in principle, 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] FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus 1 to which a wireless communication system according to this embodiment is applied. The X-ray CT apparatus 1 collects CT image data of a subject. Specifically, the X-ray CT apparatus 1 rotates an X-ray tube and an X-ray detector around the subject, detects X-rays that have passed through the subject, and collects projection data. The X-ray CT apparatus 1 then generates CT image data based on the collected projection data. As shown in FIG. 1, the X-ray CT apparatus 1 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 tabletop 33 of the bed device 30 is defined as the Z-axis direction. The axis direction that is perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction. The axis direction that is perpendicular to the Z-axis direction and vertical to the floor surface is defined as the Y-axis direction. For the sake of explanation, FIG. 1 depicts the gantry device 10 from multiple directions, and shows a case where the X-ray CT device 1 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 when a high voltage is applied 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 the irradiation range of the X-rays that have passed through the wedge 16, and a slit is formed by combining a plurality of lead plates or the like. The collimator 17 is also sometimes 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 irradiated from the X-ray tube 11 and whose irradiation range has been 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 that have been irradiated from the X-ray tube 11 and passed 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 focal point of the X-ray tube 11. The X-ray detector 12 has, for example, a structure in which 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 a photosensor array. The scintillator array has multiple scintillators. The scintillator has scintillator crystals that output light with a photon amount 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 a function of converting the amount of light from the scintillator into an electrical signal corresponding to the amount of light, and has a photosensor such as a photodiode. The X-ray detector 12 may also be a direct conversion type detector having a semiconductor element that converts incident X-rays into an electrical signal.

[0018] X-ray high voltage device 14 has electrical 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.

[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 amplifies the electrical signals output from each detection element and an A / D converter that converts the electrical signals into digital signals, and generates detection data. The DAS 18 is realized by, for example, a processor. 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 using a control device 15. For example, the rotating frame 13 is an aluminum casting. 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] The control device 15 includes 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 input signals 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, and the operation of the bed 30 and the tabletop 33. As an example, to control the tilt of the gantry 10, the control device 15 rotates the rotating frame 13 around an axis parallel to the X-axis direction based on input inclination angle (tilt angle) information. The control device 15 may be provided in the gantry 10 or in the console device 40.

[0022] 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 addition to the top plate 33 in the longitudinal direction of the top plate 33.

[0023] 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.

[0024] 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. Furthermore, for example, the memory 41 stores programs that enable circuits included in the X-ray CT apparatus 1 to realize their functions. The memory 41 may also be realized by a group of servers (cloud) connected to the X-ray CT apparatus 1 via a network.

[0025] The display 42 displays various types of information. For example, the display 42 displays various images generated by the processing circuitry 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 gantry 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.

[0026] The input interface 43 accepts various input operations from the operator, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuitry 44. For example, the input interface 43 accepts input operations from the operator, such as reconstruction conditions for reconstructing CT image data and image processing conditions for generating post-processed images from the CT image data. For example, the input interface 43 may be implemented by a mouse, keyboard, trackball, switch, button, joystick, a touchpad for performing input operations by touching the operation surface, a touchscreen integrating a display screen and a touchpad, a non-contact input circuit using an optical sensor, a voice input circuit, or the like. The input interface 43 may also be provided in the gantry 10. The input interface 43 may also be implemented by 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 those having physical operation components such as a mouse and 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 as an example of the input interface 43.

[0027] The processing circuitry 44 controls the overall operation of the X-ray CT apparatus 1. For example, the processing circuitry 44 executes a system control function 440, a scan control function 441, a preprocessing function 442, a reconstruction processing function 443, and a display control function 444.

[0028] 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 .

[0029] 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 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 collection by the DAS 18 by sending a control signal to the DAS 18.

[0030] The preprocessing function 442 generates preprocessed data by performing preprocessing on the X-ray detection data transmitted from the DAS 18. Specifically, the preprocessing function 442 generates preprocessed data by performing logarithmic conversion processing and correction processing such as offset correction, sensitivity correction, and beam hardening correction. Note that the data before preprocessing (X-ray detection data) and the data after preprocessing may be collectively referred to as projection data.

[0031] 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), iterative approximation, etc.). The reconstruction processing function 443 also stores the generated CT image data in the memory 41.

[0032] The display control function 444 causes the display 42 to display various images generated by the processing circuitry 44. For example, the display control function 444 causes the display 42 to display CT image data generated by the reconstruction processing function 443.

[0033] 1, each processing function is stored in the form of a program executable by a computer in memory 41. Processing circuitry 44 is a processor that realizes the function corresponding to each program by reading and executing the program from memory 41. In other words, once each program has been read, processing circuitry 44 has the function corresponding to the read program.

[0034] The term "processor" used in the above description refers to circuits such as a central processing unit (CPU), a graphics processing unit (GPU), and an application-specific integrated circuit (ASIC). The term "processor" also refers to circuits such as a programmable logic device. Examples of programmable logic devices include simple programmable logic devices (SPLDs) and complex programmable logic devices (CPLDs). Examples of programmable logic devices include field programmable gate arrays (FPGAs). When the processor is a CPU, for example, the processor realizes its functions by reading and executing a program stored in memory 41. On the other hand, when the processor is an ASIC, for example, the program is directly embedded in the processor circuitry instead of storing the program in memory 41. Note that each processor in this embodiment is not limited to being configured as a single circuit, but may be configured as a single processor by combining multiple independent circuits to realize its functions. Furthermore, the functions of the multiple components in FIG. 1 may be realized by integrating them into a single processor.

[0035] Here, 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 by wireless communication from the communication device provided on the rotating frame 13 to the communication device provided on the fixed frame 19, and then transferred to the console device 40. For example, a control signal for the rotating frame 13 transmitted by the console device 40 is transmitted by wireless communication from the communication device provided on the fixed frame 19 to the communication device provided on the rotating frame 13. The communication devices provided on the rotating frame 13 and the communication devices provided on the fixed frame 19 constitute a wireless communication system 100, which will be described later.

[0036] FIG. 2 is a block diagram showing an example of the configuration of a wireless communication system 100 according to this embodiment.

[0037] In this embodiment, a mode in which N-channel signals are transmitted from transmission couplers arranged on the fixed frame 19 to reception couplers arranged in a ring shape on the rotating frame 13 will be described.

[0038] The wireless communication system 100 includes a receiving communication device 101 , a transmitting communication device 102 , and a mobility control unit 103 .

[0039] First, we will explain the transmitting communication device 102. The transmitting communication device 102 has a transmission signal control unit 160, (N+1) transmitters 122, and (N+1) transmission couplers 121. Here, N is an integer equal to or greater than 2.

[0040] The transmission signal control unit 160 has a function of receiving N channel signals from the signal generation unit 180 (described later), switching or controlling the signals based on a control signal from the mobility control unit 103, and outputting the signals to each transmitter 122. Here, it is necessary to connect the transmission signal control unit 160 and each transmitter 122 so that the effective electrical lengths between them are approximately equal, or to control the propagation times by using delay elements or the like. A control method based on the control signal from the mobility control unit 103 will be described in detail in the examples described later. Furthermore, the transmission signal control unit 160 may have an opto-electrical conversion function, various equalizers, a clock recovery function, etc. for receiving signals from the signal generation unit 180, and may also have a transmission signal compensation function such as emphasis.

[0041] The transmitter 122 adjusts the output level of the transmission signal from the transmission signal control unit 160, shapes the waveform, and outputs the signal to the transmission coupler 121. Specifically, the transmitter 122 may have a waveform shaping function such as emphasis or a signal amplification function using an RF amplifier, and may have an output configuration such as a differential buffer or single-ended. Alternatively, the transmitter 122 may be configured by combining an amplifier, a distributor, an attenuator, a switch, etc.

[0042] The transmitting coupler 121 may be an antenna or directional coupler used in proximity communication using capacitance or an electric field, magnetic field, or electromagnetic field. The length of the transmitting coupler 121 is determined by the transmission speed and encoding method, and the transmitting coupler 121 is formed of a circuit board, conductive material, or the like. In addition, a sensor or the like may be provided to measure the distance to the receiving coupler (described later) or the offset between the couplers.

[0043] The transmitters 122 and the transmission couplers 121 can be connected via a transmission line or a connector, or directly by soldering, etc. Here, it is preferable that the propagation delay times between each transmitter 122 and each transmission coupler 121 are set to be approximately equal.

[0044] In this embodiment, it is assumed that a signal switched by a control signal from the transmission signal control unit 160 is converted into a desired output waveform from the transmitter 122 and output to the transmission coupler 121, but there is no particular limitation, and each transmitter 122 may itself switch its output by a control signal from the mobility control unit 103. Note that when switching is performed by the transmitter 122, the signal generation unit 180 and each transmitter 122 need to be connected so that the electrical lengths from the transmitter 122 to the signal generation unit 180 are approximately equal.

[0045] Next, a description will be given of the receiving communication device 101. The receiving communication device 101 has N receivers 112, 2N receiving couplers 111, and N termination units (not shown).

[0046] The length of the receiving coupler 111 in the extension direction is longer than that of the transmitting coupler 121. Hereinafter, the receiving coupler 111 may be referred to as a long coupler, and the transmitting coupler 121 may be referred to as a short coupler.

[0047] The receiving coupler 111 is configured with transmission lines whose electrical lengths are approximately equal. For example, the receiving coupler 111 has both ends of its transmission line terminated, and is connected to the receiver 112 at approximately equal electrical lengths from each end, that is, at the center. The transmission line can also be divided into two. In this case, for example, the receiver 112 has a multiplexer, and one end of each long coupler is connected to the multiplexer of the receiver 112, and the other end is connected to a termination unit (not shown). Examples of the termination unit configuration include a resistor that is approximately equal to the characteristic impedance of the long coupler connected to ground, a resistor that is approximately equal to the differential characteristic impedance connected between the differential transmission lines, or a termination structure with a topology such as Thevenin termination, T-type, or Π-type termination, and are not particularly limited.

[0048] The receiving coupler 111 is formed of a circuit board material such as a general printed circuit board material or a flexible substrate. The receiving coupler 111 is preferably in the form of a transmission line that transmits differential signals, but the form is not particularly limited, and various types of transmission lines such as microstrip and coplanar may be used. Furthermore, a conductive support member that supports the long coupler (receiving coupler 111) can be used as the reference potential, and the transmission form is not limited. In addition, the form of a transmission line that transmits differential signals is preferable. The long coupler functions as a coupler that realizes wireless communication between the receiving communication device 101 and the transmitting communication device 102 by coupling with the short coupler in an electric field or electromagnetic field.

[0049] The receiver 112 includes a receiving circuit that converts the voltage and current waveforms (analog signals) generated in the long-length coupler by electric or electromagnetic field coupling into digital signals and outputs the digital signals to the device to which the signals are to be transmitted. Various circuits can be used as the conversion means, but a comparator with hysteresis characteristics is preferred. The receiver 112 may also include various passive components such as low-pass filters, high-pass filters, band-pass filters, common mode filters, and beads, as well as active components such as amplifiers and functions for correcting frequency characteristics. If the distance between the receiver 112 and the device to which the signals are to be transmitted is long or the transmission speed is high, a transmission method such as optical fiber can be used. In this case, the receiver 112 may have, for example, an opto-electrical conversion function.

[0050] The movement control unit 103 moves the receiving communication device 101 and the transmitting communication device 102 relatively in a predetermined direction while supporting the receiving communication device 101 and the transmitting communication device 102 so that the long coupler (receiving coupler 111) and the short coupler (transmitting coupler 121) maintain a positional relationship in which they face each other. For example, the movement control unit 103 is composed of a rail that supports the communication device 100, a motor for moving the communication device 100 along the rail, a power supply that supplies power to the motor, etc. For example, the movement control unit 103 corresponds to a device that controls the rotation mechanism of the X-ray CT apparatus 1. For example, the movement control unit 103 corresponds to the control device 15. The movement control unit 103 also outputs a control signal to the transmission signal control unit 160, the control signal including angle information such as a rotation angle, position information, and a switching signal.

[0051] In this way, the wireless communication system 100 performs wireless communication by electromagnetic field coupling between the long coupler (receiving coupler 111) and the short coupler (transmitting coupler 121) while the receiving communication device 101 and the transmitting communication device 102 move relative to each other. Note that the electromagnetic field coupling in this embodiment includes both electric field coupling and magnetic field coupling. In other words, wireless communication between transmission lines may be performed by electric field coupling, magnetic field coupling, or both electric field coupling and magnetic field coupling.

[0052] The wireless communication system according to the present embodiment has been described above. With this configuration, the wireless communication system according to the present embodiment performs stable communication between the rotating unit and the fixed unit when simultaneously performing data communication over multiple channels. In wireless communication systems, for example, a configuration in which the transmitting side is a long coupler (long transmission) and the receiving side is a short coupler (short reception) is known. Here, even in a configuration in which the transmitting side is a short coupler (short transmission) and the receiving side is a long coupler (long reception), it is desirable to perform stable communication between the rotating unit and the fixed unit.

[0053] Therefore, the wireless communication system 100 according to this embodiment includes a signal generating unit 180, a receiving communication device 101, a transmitting communication device 102, and a switching unit. The signal generating unit 180 divides data and outputs signals of multiple channels (N channels). The receiving communication device 101 receives N channel signals from 2N receiving couplers 111 (long couplers) arranged at intervals along the circumferential direction on one of the fixed frame 19 and the rotatable frame 13. The transmitting communication device 102 transmits N channel signals from (N+1) transmitting couplers 121 (short couplers) arranged at intervals along the circumferential direction on the other of the fixed frame 19 and the rotatable frame 13, the number of which is greater than the number of channels N. The switching unit assigns the signals of the multiple channels output from the signal generating unit 180 to each transmitting coupler 121. Here, when one of the (N+1) transmitting couplers 121 passes near the separation between two circumferentially adjacent receiving couplers 111, the switching unit switches the signal transmitted from that transmitting coupler 121 to the two receiving couplers 111 to a signal of the same channel. Furthermore, for the two transmitting couplers 121 facing the two circumferentially adjacent receiving couplers 111, respectively, the switching unit stops or relatively attenuates the signal output to one of the two transmitting couplers 121.

[0054] In the wireless communication system 100 according to this embodiment, the transmitting side is a short coupler (short transmission) and the receiving side is a long coupler (long reception). The rotating frame 13 and the fixed frame 19 are examples of a "rotating unit" and a "fixed unit", respectively. The 2N receiving couplers 111 (long couplers) are an example of a "plurality of receiving media". The (N+1) transmitting couplers 121 (short couplers) are an example of a "plurality of transmitting media". The transmitting signal control unit 160 is an example of a "switching unit".

[0055] [First Example] Next, a communication control method according to the positional relationship between transmission coupler 121, which is a transmission medium, and reception coupler 111, which is a reception medium, and the processing of signal generation unit 180 and transmission signal control unit 160 will be described with reference to FIGS. 2 and 3A.

[0056] Fig. 3A is a diagram showing an example of the configuration of a wireless communication system 100 according to the first embodiment. Fig. 3B is a diagram showing an example of a 2-channel receiving communication device 101 obtained by dividing the receiving side into two, as a receiving communication device 101 of the wireless communication system 100 according to the first embodiment.

[0057] 3A, the receiving communication device 101 has two (N=2) receivers 112, four (2N=4) receiving couplers 111, and two (N=2) termination units 114. In this case, the two receivers 112 are referred to as receivers 112_1 and 112_2, and the four receiving couplers 111 are referred to as receiving-side long couplers 111_A, 111_B, 111_C, and 111_D. The transmitting communication device 102 has three (N+1=3) transmitters 122 and three (N+1=3) transmitting couplers 121. In this case, the three transmitters 122 are referred to as transmitters 122_1 (Tx1), 122_2 (Tx2), and 122_3 (Tx3), and the three transmitting couplers 121 are referred to as transmitting-side short couplers 121_1, 121_2, and 121_3. The angle formed between the receiver 112_1 and the transmitter 122_1 (Tx1) is referred to as θ. Specifically, the angle formed between the line connecting the center of rotation of the rotating frame 13 and the receiver 112_1 and the line connecting the center of rotation and the transmitter 122_1 (Tx1) is referred to as θ.

[0058] In this embodiment, a case will be described in which the rotatable frame 13 rotates clockwise, but for ease of understanding, the following description will be given assuming that the rotatable frame 13 is fixed and the fixed-side transmitter 122 rotates counterclockwise relatively. The example shown in Fig. 3A shows a state in which the rotatable frame 13 has rotated 15 degrees clockwise, causing the fixed-side transmitter 122 to rotate 15 degrees counterclockwise relatively, and the angle (rotation angle) θ between the fixed-side transmitter 122_1 (Tx1) and the rotatable-side receiver 112_1 is 15 degrees.

[0059] 3A, the receiving communication device 101 is arranged in the rotating frame 13, and the transmitting communication device 102 is arranged in the fixed frame 14. That is, in the wireless communication system 100 according to this embodiment, the transmitting side is configured as a short coupler (short length transmission) and the receiving side is configured as a long length coupler (long length reception), so that, for example, the wireless communication system 100 performing short length transmission and long length reception is applied to the uplink of the X-ray CT scanner 1. In this case, the signal generation unit 180 is the console device 40 of the X-ray CT scanner 1 or a device connected to the console device 40, and divides data to output N channel signals. The data is a control signal for the rotating frame 13 transmitted by the console device 40.

[0060] On the rotating frame 13, four long couplers 111_A to 111_D on the receiving side, each having approximately the same length in the circumferential direction, are arranged at intervals along the circumferential direction of the rotating frame 13 as the receiving communication device 101.

[0061] In the receiving communication device 101, receivers 112_1 and 112_2 process two-channel (2ch) signals received by receiving-side long couplers 111_A, 111_B, 111_C, and 111_D. For example, one end of the receiving-side long couplers 111_A, 111_B, 111_C, and 111_D is terminated by a termination unit 114, and four long couplers are arranged in a ring so that the ends of the long couplers are adjacent to each other. Here, a termination circuit is provided at one end of each of the long couplers 111_A and 111_D, and the portions where the termination circuits are arranged adjacent to each other are referred to as the termination unit 114. Similarly, one end of the long couplers 111_B and 111_C is provided with a termination circuit, and the portions where the termination circuits are arranged adjacent to each other are referred to as the termination unit 114. The other ends of the receiving-side long couplers 111_A, 111_B, 111_C, and 111_D are connected to receivers 112_1 and 112_2, respectively. As a result, in the example shown in Fig. 3A, the receiver 112_1 processes the signals of the channels received by the receiving-side long couplers 111_A and 111_B, and the receiver 112_2 processes the signals of the channels received by the receiving-side long couplers 111_C and 111_D. For example, the receiver 112_1 processes the signal of "ch1" as the signal of channel 1, and the receiver 112_2 processes the signal of "ch2" as the signal of channel 2.

[0062] The fixed frame 14 includes, as a transmitting side communication device 102, a signal generating unit 180, a transmission signal control unit 160, transmitters 122_1 (Tx1), 122_2 (Tx2), 122_3 (Tx3), and transmitting side short couplers 121_1, 121_2, 121_3.

[0063] In the transmitting communication device 102, the transmitting-side short couplers 121_1, 121_2, and 121_3 are arranged at approximately equal intervals from the rotation center of the rotating frame 13 and spaced apart in the circumferential direction of the rotating frame 13. In the example shown in Fig. 3A, the transmitting-side short couplers 121_1, 121_2, and 121_3 are arranged to have a positional relationship of 120 degrees from each other, but they do not necessarily have to be arranged at exactly 120 degrees. The transmitting-side short couplers 121_1, 121_2, and 121_3 are arranged so that the short couplers and the long couplers face each other and maintain a state in which they are coupled to the receiving-side long couplers 111_A, 111_B, 111_C, and 111_D by electromagnetic field coupling.

[0064] In the transmitting communication device 102, the transmission signal control unit 160 allocates the two-channel signals output from the signal generation unit 180 to transmitters 122_1 (Tx1), 122_2 (Tx2), and 122_3 (Tx3) in accordance with a control signal including angle information such as a rotation angle, position information, and a switching signal output from the movement control unit 103.

[0065] The transmitters 122_1 (Tx1), 122_2 (Tx2), and 122_3 (Tx3) control the waveform or amplitude of a signal to be output to the short couplers 121_1, 121_2, and 121_3 on the transmitting side in response to a signal from the transmission signal control unit 160. Examples of the control of the waveform or amplitude include the amplification degree of an amplifier, the attenuation amount of a variable attenuator, and on / off of the output by a switch connection. Note that the signal control means is not limited to this, and may be implemented by software that sets the output of an output driver, or by other hardware configurations.

[0066] There are various timings for switching signals depending on how close the corresponding transmitting short coupler 121 is to the opposing receiving coupler 111. For example, signal switching is performed based on information such as the rotation angle and position when the rotation of the rotating frame 13 is controlled, or a movement sequence preset in the system.

[0067] 3A, a channel 1 signal "ch1" is transmitted from a transmitter 122_1 (Tx1) to a receiving-side long coupler 111_B via a transmitting-side short coupler 121_1, and a channel 2 signal "ch2" is transmitted from a transmitter 122_3 (Tx3) to a receiving-side long coupler 111_C via a transmitting-side short coupler 121_3. In this case, the channel 1 signal "ch1" can be received by a receiver 112_1 connected to the receiving-side long coupler 111_B, and the channel 2 signal "ch2" can be received by a receiver 112_2 connected to the receiving-side long coupler 111_C.

[0068] Here, if the transmitter 122_2 (Tx2) outputs the channel 2 signal "ch2" to the receiving side long coupler 111_D via the transmitting side short coupler 121_2, the channel 2 signal "ch2" can be received by the receiver 112_2 connected to the long coupler 111_D.

[0069] As described above, the receivers 112_1 and 112_2 each include a multiplexer that combines channel signals received by two circumferentially adjacent receiving couplers 111, and a receiving circuit (comparator). For example, in the receiver 112_2, the multiplexer combines the signal "ch2" of channel 2 received by the long coupler 111_C on the receiving side and the signal "ch2" of channel 2 received by the long coupler 111_D on the receiving side, and the comparator converts the analog signal output from the multiplexer into a digital signal.

[0070] However, while this is not a problem when the transmission speed of the transmitted signal is low, if the transmission speed is high, it may become a problem because the phase of the signal from the receiving side long coupler 111_C and the signal from the receiving side long coupler 111_D input to the multiplexer will be out of phase.

[0071] This will be explained using Figures 3A, 3B, 4A, and 4B. As shown in Figure 3A, the propagation length of the long coupler 111_C on the receiving side from the short coupler 121_3 on the transmitting side to the receiver 112_2 via the long coupler 111_C on the receiving side is set to L1, and the propagation length of the long coupler 11_D from the short coupler 121_2 on the transmitting side to the receiver 112_2 via the long coupler 11_D is set to L2. In this case, in the example shown in Figure 3A (θ = 15 degrees), the propagation distance of the propagation length L2 is longer than the propagation length L1.

[0072] 4A and 4B are diagrams showing examples of received waveforms in the wireless communication system 100 according to the first embodiment. Fig. 4A shows an example of the waveform at the receiver 112_2 when the difference in propagation distance is relatively short. Note that the example of the waveform shown in Fig. 4A is an example assuming a waveform when a contactless signal is received with an impedance of about 50 Ω single and 100 Ω differential, which are used for general high-speed signals.

[0073] 4A, the signal levels (logical values) of the signals transmitted from the short couplers 121_2 and 121_3 on the transmitting side (hereinafter referred to as transmission signals) transition in the order of "L (low level)", "H (high level)", and "L" from the time T = 0. The input signals from the long coupler 111_C on the receiving side to the multiplexer and from the long coupler 111_D on the receiving side to the multiplexer change at the rising and falling edges of the transmission signals.

[0074] For example, in the waveform shown in the upper part of Figure 4A, when the signal level of the transmission signal transitions from "L" to "H," the capacitor formed by the long coupler on the receiving side and the short coupler on the transmitting side begins to charge, causing the potential of the long coupler on the receiving side to rise from the reference potential of the receiver 112. Next, when the signal level of the transmission signal is held at "H," the charge stored in the capacitor begins to discharge, causing the potential of the long coupler on the receiving side to drop toward the reference potential. Note that, for the sake of simplicity, the propagation delay time in the long coupler is omitted from the timing chart of Figure 4A.

[0075] The signals input from the receiving-side long coupler 111_C and the receiving-side long coupler 111_D to the multiplexer of the receiver 112_2 are combined by the multiplexer, and the signal output from the multiplexer is input to the receiving circuit of the receiver 112_2. Here, a comparator with hysteresis characteristics is used as the receiving circuit. Two thresholds TH and TL are set in the comparator.

[0076] In the waveform shown in the lower part of FIG. 4A, first, an input signal is input to the comparator of the receiver 112_2, and the comparator maintains the signal level of the output signal at "L" until a potential exceeding the upper threshold TH is input to the comparator as an input signal. Next, a potential exceeding the upper threshold TH is input to the comparator as an input signal, and the comparator maintains the signal level of the output signal at "H" until the signal level (logical value) of the input signal falls below the lower threshold TL. Next, when a potential whose signal level is below the lower threshold TL is input to the comparator as an input signal, the comparator transitions the signal level of the output signal to "L," and maintains the signal level of the output signal at "L" until a potential exceeding the upper threshold TH is input to the comparator as an input signal.

[0077] The input to the comparator, which is a receiving circuit, is a signal added (combined) by the multiplexer, and the analog signal output from the multiplexer is converted into a digital signal by the operation of the comparator described above. Here, the output signals (channel 1 signal "ch1" and channel 2 signal "ch2") output from the comparators of the receivers 112_1 and 112_2, respectively, become control signals for the rotating frame 13.

[0078] In the waveforms shown in the upper part of Fig. 4A, the difference between the signal input from long coupler 111_C on the receiving side to the multiplexer and the signal input from long coupler 111_D on the receiving side to the multiplexer is ΔT. As shown in Fig. 4A, when the time difference ΔT is shorter than the transition time of one bit of the transmission signal (unit interval = UI), the effect of the difference in signal propagation time is small, and the output signal output from receiver 112_2 (in this case, signal "ch2" of channel 2) is normal. However, as shown in Fig. 4B, when the time difference ΔT becomes 1 UI or more, there is an increased possibility that an error will occur in the output signal output from receiver 112_2.

[0079] 3A, when a signal is transmitted from the short coupler 121_2 on the transmitting side to the long coupler 111_D on the receiving side, the transmission signal control unit 160 controls the output of the transmitter 122_2 (Tx2) to stop or relatively attenuate the signal output to the short coupler 121_2 on the transmitting side. As a result, the wireless communication system 100 according to the first embodiment can reduce the influence of phase shift due to differences in propagation length depending on the angle, thereby improving communication quality.

[0080] The signal "ch1" from channel 1 and the signal "ch2" from channel 2 received by the long coupler are converted into digital signals by each receiving circuit, but other signal processing such as frequency characteristic correction and common mode noise removal may also be performed.

[0081] In the above example, the short coupler 121_1 on the transmitting side transmits a signal "ch1" on channel 1, and the short coupler 121_3 on the transmitting side transmits a signal "ch2" on channel 2. While maintaining this transmission condition, the rotating frame 13 is rotated counterclockwise, and when the rotation angle θ formed between the fixed-side transmitter 122_1 (Tx1) and the rotating-side receiver 112_1 exceeds 90 degrees, the short coupler 121_1 on the transmitting side no longer faces the long coupler 111_B on the receiving side, but faces the long coupler 111_C on the receiving side. Furthermore, the short coupler 121_3 on the transmitting side no longer faces the long coupler 111_C on the receiving side, but faces the long coupler 111_D on the receiving side.

[0082] In this case, the multiplexer of the receiver 112_2 receives the signal "ch1" of channel 1 received by the long receiving coupler 111_C and the signal "ch2" of channel 2 received by the long receiving coupler 111_D, resulting in signal interference. Furthermore, the multiplexer of the receiver 112_1 receives the signal received by the long receiving coupler 111_A and the signal received by the long receiving coupler 111_B, but the transmission signal from the short transmitting coupler 121_2 opposite the long receiving coupler 111_A is stopped or attenuated, making it difficult for the receiver 112_1 to receive the signal "ch1" of channel 1. For this reason, it is necessary to appropriately switch the transmission signal at the rotation angle θ.

[0083] Therefore, in the wireless communication system 100 according to the first embodiment, for two short transmitting couplers that face two long receiving couplers that are adjacent in the circumferential direction, the transmission signal control unit 160 stops or relatively attenuates the signal output to one of the two short transmitting couplers, depending on the propagation length to one receiver provided in the two long receiving couplers. This will be described in detail.

[0084] Fig. 5 is a diagram showing an example of the configuration of the wireless communication system 100 according to the first embodiment when it rotates. Fig. 6 is a diagram showing the relationship between the rotation angle and the output of the transmission signal in the wireless communication system 100 according to the first embodiment. Figs. 5 and 6 show an example in which, like the example shown in Fig. 3A, N=2 and the rotating frame 13 rotates clockwise, causing the fixed-side transmitter 122 to rotate counterclockwise relatively.

[0085] 5 and 6, similarly to the example shown in Fig. 3A, the short couplers 121_1, 121_2, and 121_3 on the transmitting side are arranged to have a positional relationship of 120 degrees relative to one another. For example, when the rotation angle θ formed between the fixed-side transmitter 122_1 (Tx1) and the rotating-side receiver 112_1 is 60 degrees, the short coupler 121_1 on the transmitting side is at a position of 60 degrees, the short coupler 121_3 on the transmitting side is at a position of 180 degrees, and the short coupler 121_2 on the transmitting side is at a position of 300 degrees.

[0086] For example, the transmission signal control unit 160 controls the transmitter 122_1 (Tx1) to output a signal "ch1" of channel 1 from the short coupler 121_1 on the transmitting side, controls the transmitter 122_3 (Tx3) to output a signal "ch2" of channel 2 from the short coupler 121_3 on the transmitting side, and controls the transmitter 122_3 (Tx3) not to output a signal from the short coupler 121_2 on the transmitting side.

[0087] Here, when the angle θ formed between the transmitter 122_1 (Tx1) and the receiver 112_1 is 60 degrees, the short coupler 121_3 on the transmitting side passes near the separation portion between two long couplers 111_C and 111_D on the receiving side that are adjacent in the circumferential direction. At this time, the transmission signal control unit 160 controls the transmitter 122_3 (Tx3) to switch the signal to be transmitted from the short coupler 121_3 on the transmitting side to the long couplers 111_C and 111_D on the receiving side to the signal "ch2" on the same channel. In this case, the signal "ch1" on channel 1 is input to the receiver 112_1 from the long coupler 111_B on the receiving side, and the signal "ch2" on channel 2 is input to the receiver 112_2 from both the long coupler 111_C and the long coupler 111_D on the receiving side, thereby establishing communication. However, the angle θ formed between the short coupler 121_1 on the transmitting side and the receiver 112_1 is 60 degrees, and the angle θ formed between the short coupler 121_2 on the transmitting side and the receiver 112_1 is also 60 degrees. That is, the time it takes for the signal output from the short coupler 121_1 on the transmitting side to propagate to the receiver 112_1 is approximately equal to the time it takes for the signal output from the short coupler 121_2 on the transmitting side to propagate to the receiver 112_1. Therefore, the transmission signal control unit 160 switches the transmission signal at an angle at which the propagation distances from each short coupler 121 on the transmitting side to the receiver 112 are approximately equal. For example, the transmission signal control unit 160 controls the transmitter 122_2 (Tx2) to output the channel 1 signal "ch1" from the transmitting side short coupler 121_2, which had stopped outputting, and controls the transmitter 122_1 (Tx1) to stop outputting the channel 1 signal "ch1" from the transmitting side short coupler 121_1.

[0088] That is, as shown in FIG. 6, when the angle θ between the transmitter 122_1 (Tx1) and the receiver 112_1 is 60 degrees, the transmission signal control unit 160 controls the transmitter 122_1 (Tx1) so as not to output a signal from the transmitting-side short coupler 121_1, controls the transmitter 122_2 (Tx2) so as to output the channel 1 signal "ch1" from the transmitting-side short coupler 121_2, and controls the transmitter 122_3 (Tx3) so as to output the channel 2 signal "ch2" from the transmitting-side short coupler 121_3.

[0089] Similarly, when the angle θ formed between the transmitter 122_1 (Tx1) and the receiver 112_1 is 120 degrees, the short coupler 121_2 on the transmitting side passes near the separation portion between two long couplers 111_A and 111_B on the receiving side that are adjacent in the circumferential direction. At this time, the transmission signal control unit 160 controls the transmitter 122_2 (Tx2) so as to switch the signal to be transmitted from the short coupler 121_2 on the transmitting side to the long couplers 111_A and 111_B on the receiving side to the signal "ch1" on the same channel. In this case, the angle θ formed between the short coupler 121_1 on the transmitting side and the receiver 112_2 is 60 degrees, and the angle θ formed between the short coupler 121_3 on the transmitting side and the receiver 112_2 is also 60 degrees. That is, the time taken for the signal output from the short coupler 121_1 on the transmitting side to propagate to the receiver 112_2 is approximately equal to the time taken for the signal output from the short coupler 121_3 on the transmitting side to propagate to the receiver 112_2. Therefore, the transmission signal control unit 160 controls the transmitter 122_1 (Tx1) to output the signal "ch2" of channel 2 from the short coupler 121_1 on the transmitting side, which has stopped outputting, and controls the transmitter 122_3 (Tx3) to stop outputting the signal "ch2" of channel 2 from the short coupler 121_2 on the transmitting side, which has been outputting the signal "ch2".

[0090] That is, as shown in FIG. 6, when the angle θ between the transmitter 122_1 (Tx1) and the receiver 112_1 is 120 degrees, the transmission signal control unit 160 controls the transmitter 122_1 (Tx1) to output the channel 2 signal "ch2" from the transmitting side short coupler 121_1, controls the transmitter 122_2 (Tx2) to output the channel 1 signal "ch1" from the transmitting side short coupler 121_2, and controls the transmitter 122_3 (Tx3) not to output a signal from the transmitting side short coupler 121_3.

[0091] In this way, the transmission signal control unit 160 switches the transmission signal at an angle where the propagation distance from each transmitting short coupler 121 to the receiver 112 is approximately equal, so that N channel signals are input to the receiver 112, enabling stable communication regardless of rotational movement.

[0092] Although the present embodiment has been described taking the case where the rotatable frame 13 rotates clockwise as an example, it is also possible to rotate the rotatable frame 13 counterclockwise. Even in this case, it is sufficient to switch the transmission signal at an angle where the propagation distances from each transmitting coupler to the receiver 112 are approximately equal.

[0093] As explained above, in the wireless communication system 100 according to the first embodiment, the signal output to one of the two short transmitting couplers 121 is stopped or relatively attenuated depending on the propagation length to the receivers 112 provided in the two long receiving couplers 111. As a result, in the wireless communication system 100 according to the first embodiment, stable communication can be performed between the rotating frame 13 and the fixed frame 14 when transmitting two-channel signals in one lane.

[0094] [Second Example] Fig. 7 is a diagram showing an example of the configuration of a wireless communication system 100 according to a second embodiment. Fig. 8 is a diagram showing the relationship between the rotation angle and the output of a transmission signal in the wireless communication system 100 according to the second embodiment. Here, Figs. 7 and 8 show an example of a 3-channel (N=3) wireless communication system in which the receiving side is divided into three. Note that the same components as those in the first embodiment are given the same reference numerals and their description will be omitted.

[0095] 7, the receiving communication device 101 has three (N=3) receivers 112, six (2N=6) receiving couplers 111, and three (N=3) termination units 114. In this case, the three receivers 112 are referred to as receivers 112_1, 112_2, and 112_3, and the six receiving couplers 111 are referred to as receiving-side long couplers 111_A, 111_B, 111_C, 111_D, 111_E, and 111_F. The transmitting communication device 102 has four (N+1=4) transmitters 122 and four (N+1=4) transmitting couplers 121. In this case, the four transmitters 122 are referred to as transmitters 122_1 (Tx1), 122_2 (Tx2), 122_3 (Tx3), and 122_4 (Tx4), and the four transmitting couplers 121 are referred to as transmitting-side short couplers 121_1, 121_2, 121_3, and 121_4. The angle formed between the receiver 112_1 and the transmitter 122_1 (Tx1) is referred to as θ. Specifically, the angle formed between the line connecting the center of rotation of the rotating frame 13 and the receiver 112_1 and the line connecting the center of rotation and the transmitter 122_1 (Tx1) is referred to as θ.

[0096] 7 and 8 show an example in which the fixed-side transmitter 122 rotates counterclockwise relative to the fixed-side transmitter 122 due to the clockwise rotation of the rotating frame 13. In the example shown in Fig. 7, the angle (rotation angle) θ between the fixed-side transmitter 122_1 (Tx1) and the rotating-side receiver 112_1 is 45 degrees.

[0097] 7, similarly to the first embodiment (FIGS. 3A, 5, and 6), the receiving communication device 101 is arranged on the rotating frame 13, and the transmitting communication device 102 is arranged on the fixed frame 14. That is, in the wireless communication system 100 according to this embodiment, the transmitting side is configured as a short coupler (short-length transmission) and the receiving side is configured as a long coupler (long-length reception). Therefore, for example, the wireless communication system 100 performing short-length transmission and long-length reception is applied to the uplink of the X-ray CT scanner 1. In this case, the signal generation unit 180 is the console device 40 of the X-ray CT scanner 1 or a device connected to the console device 40, and divides data to output three-channel (N=3) signals. The data is a control signal for the rotating frame 13 transmitted by the console device 40.

[0098] On the rotating frame 13, six long couplers 111_A to 111_F on the receiving side, each having approximately the same length in the circumferential direction, are arranged at intervals along the circumferential direction of the rotating frame 13 as the receiving communication device 101.

[0099] In the receiving-side communication device 101, receivers 112_1, 112_2, and 112_3 process three-channel (3ch) signals received by receiving-side long couplers 111_A, 111_B, 111_C, 111_D, 111_E, and 111_F. For example, one end of the receiving-side long couplers 111_A, 111_B, 111_C, 111_D, 111_E, and 111_F is terminated by a termination unit 114, and six long couplers are arranged in a ring so that the ends of the long couplers are adjacent to each other. The other ends of the receiving-side long couplers 111_A, 111_B, 111_C, 111_D, 111_E, and 111_F are connected to receivers 112_1, 112_2, and 112_3, respectively. 7, the receiver 112_1 processes the signals of the channels received by the long couplers 111_A and 111_B on the receiving side, the receiver 112_2 processes the signals of the channels received by the long couplers 111_C and 111_D on the receiving side, and the receiver 112_3 processes the signals of the channels received by the long couplers 111_E and 111_F on the receiving side. For example, the receiver 112_1 processes the signal of "ch1" as the signal of channel 1, the receiver 112_2 processes the signal of "ch2" as the signal of channel 2, and the receiver 112_3 processes the signal of "ch3" as the signal of channel 2.

[0100] The fixed frame 14 includes a transmitting side communication device 102, which includes a signal generating unit 180, a transmission signal control unit 160, transmitters 122_1 (Tx1), 122_2 (Tx2), 122_3 (Tx3), 122_4 (Tx4), and transmitting side short couplers 121_1, 121_2, 121_3, 121_4.

[0101] In the transmitting-side communication device 102, the transmitting-side short couplers 121_1, 121_2, 121_3, and 121_4 are arranged at approximately equal intervals from the rotation center of the rotating frame 13 and at intervals in the circumferential direction of the rotating frame 13. In the example shown in Fig. 7, the transmitting-side short couplers 121_1, 121_2, 121_3, and 121_4 are arranged to be at 90-degree angles to one another. The transmitting-side short couplers 121_1, 121_2, 121_3, and 121_4 are arranged so that the short couplers and the long couplers 111_A, 111_B, 111_C, 111_D, 111_E, and 111_F are opposed to each other so as to maintain a state in which the short couplers and the long couplers are coupled to each other by electromagnetic field coupling.

[0102] Here, when the angle θ formed between the transmitter 122_1 (Tx1) and the receiver 112_1 is 45 degrees, the short coupler 121_2 on the transmitting side passes near the space between two long couplers 111_C and 111_D on the receiving side that are adjacent in the circumferential direction. At this time, the transmission signal control unit 160 controls the transmitter 122_2 (Tx2) so as to switch the signal to be transmitted from the short coupler 121_2 on the transmitting side to the long couplers 111_C and 111_D on the receiving side to the signal "ch2" of the same channel. In addition, the short coupler 121_3 on the transmitting side passes near the space between two long couplers 111_E and 111_F on the receiving side that are adjacent in the circumferential direction. At this time, the transmission signal control unit 160 controls the transmitter 122_2 (Tx3) so as to switch the signal to be transmitted from the short coupler 121_3 on the transmitting side to the long couplers 111_E and 111_F on the receiving side to the signal "ch3" of the same channel. In this case, the angle θ formed between the short coupler 121_1 on the transmitting side and the receiver 112_1 is 45 degrees, and the angle θ formed between the short coupler 121_4 on the transmitting side and the receiver 112_1 is also 45 degrees. In other words, the time required for the signal output from the short coupler 121_1 on the transmitting side to propagate to the receiver 112_1 is approximately equal to the time required for the signal output from the short coupler 121_4 on the transmitting side to propagate to the receiver 112_1. Therefore, the transmission signal control unit 160 controls the transmitter 122_1 (Tx4) to output the channel 1 signal "ch1" from the transmitting side short coupler 121_4, which had stopped outputting, and controls the transmitter 122_1 (Tx1) to stop outputting the channel 1 signal "ch1" from the transmitting side short coupler 121_1, which had been outputting the channel 1 signal "ch1".

[0103] That is, as shown in FIG. 8, when the angle θ between the transmitter 122_1 (Tx1) and the receiver 112_1 is 45 degrees, the transmission signal control unit 160 controls the transmitter 122_1 (Tx1) so as not to output a signal from the transmitting-side short coupler 121_1, controls the transmitter 122_2 (Tx2) so as to output the channel 2 signal "ch2" from the transmitting-side short coupler 121_2, controls the transmitter 122_3 (Tx3) so as to output the channel 3 signal "ch3" from the transmitting-side short coupler 121_3, and controls the transmitter 122_4 (Tx4) so ​​as to output the channel 1 signal "ch1" from the transmitting-side short coupler 121_4.

[0104] In this way, the transmission signal control unit 160 switches the transmission signal at an angle where the propagation distance from each transmitting short coupler 121 to the receiver 112 is approximately equal, so that N channel signals are input to the receiver 112, enabling stable communication regardless of rotational movement.

[0105] Next, the case where N-channel signals are transmitted in one lane will be generalized using N.

[0106] The (N+1) transmitting-side short couplers 121 are arranged at approximately equal intervals from the rotation center of the rotating frame 13 and spaced apart in the circumferential direction of the rotating frame 13. That is, the transmitting-side short couplers 121 are arranged every θ1=360 / (N+1) degrees. In the example shown in Fig. 7, N=3, so the transmitting-side short couplers 121 are arranged every θ1=360 / (3+1)=90 degrees.

[0107] The 2N receiving-side long couplers 111 are arranged in a ring shape such that one end of each long coupler is terminated by a termination portion 114 and the ends of the long couplers are adjacent to each other. The other ends of the 2N receiving-side long couplers 111 are connected to N receivers 112, respectively. The receiving-side long couplers 111 connected to the receivers 112 are arranged at intervals of θ2=360 / N degrees. In the example shown in FIG. 7, since N=3, the receiving-side long couplers 111_A and 111_B connected to the receiver 112_1, the receiving-side long couplers 111_C and 111_D connected to the receiver 112_2, and the receiving-side long couplers 111_E and 111_F connected to the receiver 112_3 are arranged at intervals of θ2=360 / 3=120 degrees.

[0108] 7, the angle formed between the short coupler 121_1 on the transmitting side facing the long coupler 111_B on the receiving side and the terminal end 114 of the long coupler 111_B on the receiving side closer to the short coupler 121_1 on the transmitting side is defined as X. Specifically, the angle formed between a line connecting the center of rotation of the rotating frame 13 and the short coupler 121_1 on the transmitting side and a line connecting the center of rotation and the terminal end 114 of the long coupler 111_B on the receiving side facing the short coupler 121_1 on the transmitting side is defined as X. Also, the angle formed between the short coupler 121_4 on the transmitting side facing the long coupler 111_A on the receiving side and the terminal end 114 of the long coupler 111_A on the receiving side closer to the short coupler 121_4 on the transmitting side is defined as Y. Specifically, let Y be the angle formed by the line connecting the center of rotation of the rotating frame 13 and the short coupler 121_4 on the transmitting side and the line connecting the center of rotation and the terminal end 114 of the long coupler 111_A on the receiving side opposite the short coupler 121_4 on the transmitting side.

[0109] In this case, in order for receiver 112_1 to receive signals from transmitting-side short couplers 121_1 and 121_4 at the same timing, the propagation length of the signal input from transmitting-side short coupler 121_1 to receiver 112_1 via receiving-side long coupler 111_B and the propagation length of the signal input from transmitting-side short coupler 121_4 to receiver 112_1 via long coupler 11_A must be equal to the propagation length of the signal input from transmitting-side short coupler 121_4 to receiver 112_1 via long coupler 11_A and ... receiving-side short coupler 121_4 to receiver 112_1 via long coupler 11_A must be equal.

[0110] Here, the two long transmission lines that make up the receiving coupler 111 are set to have approximately the same length, so when the angles θ1, θ2, X, and Y have the relationship shown in equation (1), the distances from the transmitting-side short couplers 121_1 and 121_4 to the termination 114 are also equal.

[0111]

number

[0112] Therefore, when X=Y=θ3, equation (1) is expanded as shown in equation (2), and the angle of θ3 is calculated as 180 / {N(N+1)} as shown in equation (3).

[0113]

number

number

[0114] For example, in FIG. 7, when the angle X between the transmitting-side short coupler 121_1 and the terminal end 114 of the receiving-side long coupler 111_B facing the transmitting-side short coupler 121_1 is 180 / {N(N+1)} degrees or less, the transmission signal control unit 160 controls the transmitter 122_1 (Tx1) to stop or relatively attenuate the signal output to the transmitting-side short coupler 121_1. In this way, switching the signal at an angle where X=Y=θ3 prevents degradation of the received signal due to differences in propagation time caused by the rotation angle. That is, the influence of differences in signal propagation time is small, and the possibility of errors occurring in the output signal output from the receiver 112_1 is reduced.

[0115] As explained above, in the wireless communication system 100 according to the second embodiment, when the angle between the short coupler 121 on the transmitting side and the terminal end 114 of the long coupler 111 on the receiving side facing the short coupler 121 on the transmitting side is 180 / {N(N+1)} degrees or less, the signal output to the short coupler 121 on the transmitting side is stopped or relatively attenuated. As a result, in the wireless communication system 100 according to the second embodiment, stable communication can be performed between the rotating frame 13 and the fixed frame 14 when transmitting N channel signals in one lane.

[0116] In the above-described embodiment, the receiving communication device 101 is arranged on the rotating frame 13, and the transmitting communication device 102 is arranged on the fixed frame 14, but this is not limiting. For example, the transmitting communication device 102 may be arranged on the rotating frame 13, and the receiving communication device 101 may be arranged on the fixed frame 19. That is, in the wireless communication system 100 according to this embodiment, the transmitting side is a short coupler (short length transmission) and the receiving side is a long coupler (long length reception). Therefore, for example, the wireless communication system 100 performing short length transmission and long length reception is applied to the downlink of the X-ray CT scanner 1. In this case, the signal generation unit 180 is the DAS 18 of the X-ray CT scanner 1 or a device connected to the DAS 18, and the data is an X-ray signal collected by the DAS 18.

[0117] Fig. 9 is a diagram showing a specific example of the case where the wireless communication system 100 according to this embodiment is applied to an X-ray CT scanner 1. Fig. 9 shows an example where the wireless communication system 100 performing short-length transmission and long-length reception is applied to the uplink of the X-ray CT scanner 1, and the wireless communication system performing long-length transmission and short-length reception is applied to the downlink of the X-ray CT scanner 1.

[0118] The X-ray CT apparatus 1 includes a first transmitting communication device, a first receiving communication device, a second transmitting communication device, and a second receiving communication device.

[0119] The first transmitting communication device and the first receiving communication device are applied to a wireless communication system 100 that performs short-length transmission and long-length reception as an uplink of the X-ray CT scanner 1. The first transmitting communication device is the above-mentioned transmitting communication device 102, which is arranged in the fixed frame 19. The first receiving communication device is the above-mentioned receiving communication device 101, which is arranged in the rotating frame 13. In this case, the signal generating unit 180 is the console device 40 of the X-ray CT scanner 1 or a device connected to the console device 40, and divides data and outputs N-channel signals. The data is a control signal for the rotating frame 13 transmitted by the console device 40. The first receiving communication device (receiving communication device 101) is arranged in a ring 300 shown in the middle of FIG. 9.

[0120] 9, short transmission and long reception are applied to the uplink of the X-ray CT scanner 1, and N channel signals are transmitted in the first lane. Specifically, in the first transmitting communication device (transmitting communication device 102), (N+1) transmitting short couplers 121 are arranged at approximately equal intervals around the circumferential direction of the rotating frame 13 from the center of rotation of the rotating frame 13. In the first receiving communication device (receiving communication device 101), 2N receiving long couplers 111 are arranged in a ring shape such that one end of each long coupler is terminated by a termination unit 114 and the ends of the long couplers are adjacent to each other. For example, in the first lane, signals of channel 1 (ch1) and channel 2 (ch2) are output from the transmitting short coupler 121 to the receiving long coupler 111 as two transmitting channel (N=2) signals.

[0121] In the diagram shown in the upper part of Fig. 9, the angle θ formed between the receiver 112_1 and the transmitter 122_1 (the short coupler 121_1 on the transmission side) is an angle between 0 and 60 degrees. For example, when the angle θ formed between the receiver 112_1 and the short coupler 121_1 on the transmission side is approximately 40 degrees, as shown in the middle part of Fig. 9, in the first lane, the signal of channel 1 (ch1) is output from the short coupler 121_1 on the transmission side to the long coupler 111_B on the reception side, and the signal of channel 2 (ch2) is output from the short coupler 121_3 on the transmission side to the long coupler 111_C on the reception side. In this case, no signal is output from the short coupler 121_2 on the transmission side to avoid being affected by the difference in signal propagation time.

[0122] The second transmitting communication device and the second receiving communication device are applied to a wireless communication system that performs long-range transmission and short-range reception as downlinks of the X-ray CT device 1. The second transmitting communication device is arranged on the rotating frame 13, and the second receiving communication device is arranged on the fixed frame 19. The second transmitting communication device is arranged on a ring 300 in which the first receiving communication device (receiving communication device 101) is arranged, and transmits X-ray signals collected by the DAS 18 to the second receiving communication device on the fixed frame 19. In other words, the second transmitting communication device shares the ring 300 with the first receiving communication device (receiving communication device 101).

[0123] For example, in the diagram shown in the lower part of FIG. 9 , long-length transmission and short-length reception are applied to the downlink of the X-ray CT scanner 1, and M-channel signals (M is an integer equal to or greater than 2) are transmitted in the second lane. Specifically, in the second transmitting-side communication device, 2(M+1) long-length transmitting couplers 211 are terminated at one end by a termination unit 214, and are arranged in a ring shape so that the ends of the long-length couplers are adjacent to each other. In the second receiving-side communication device, M short-length receiving couplers 221 are arranged at approximately equal intervals from the rotation center of the rotating frame 13 and spaced apart in the circumferential direction of the rotating frame 13. For example, in the second lane, signals of channel 1 (ch1) and channel 2 (ch2) are output from the long-length transmitting coupler 211 to the short-length receiving coupler 221 as two-channel (M=2) transmitting-side signals.

[0124] In the diagram shown in the lower part of Fig. 9, the angle θ formed between the short coupler 221_1 on the receiving side and the other end of the long coupler 211_A on the transmitting side is between 0 and 60 degrees. For example, when the angle θ formed between the short coupler 221_1 on the receiving side and the other end of the long coupler 211_A on the transmitting side is approximately 40 degrees, as shown in the middle part of Fig. 9, in the second lane, the signal of channel 1 (ch1) is output from the long coupler 211_A on the transmitting side to the short coupler 221_1 on the receiving side, and the signal of channel 2 (ch2) is output from the long coupler 211_D on the transmitting side to the short coupler 221_2 on the receiving side. In this case, no signals are output from the long couplers 211_B, 211_C, 211_E, and 211_F on the transmitting side to avoid being affected by interference noise from adjacent lanes.

[0125] In this way, in the example shown in Figure 9, by sharing the ring 300 for the uplink of the X-ray CT device 1 (a wireless communication system 100 that performs short-length transmission and long-length reception) and the downlink of the X-ray CT device 1 (a wireless communication system that performs long-length transmission and short-length reception), it is possible to achieve miniaturization of the device in a wireless communication system that simultaneously performs data communication on multiple channels.

[0126] According to at least one of the embodiments described above, when data communication is performed simultaneously over multiple channels, stable communication can be performed between the rotating part and the fixed part.

[0127] Although several 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 within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0128] 100 Wireless Communication System 101 Receiving communication device 102 Transmitting communication device 111 Receiving coupler (long receiving coupler) 121 Transmitting coupler (short coupler on the transmitting side) 160 Transmission signal control section 180 Signal Generation Unit

Claims

1. a signal generating unit that divides data and outputs signals of multiple channels; a receiving communication device in which a plurality of receiving media are arranged at intervals along a circumferential direction on one of the fixed part and the rotating part, and which receives signals of the plurality of channels; a transmitter communication device in which a plurality of transmission media are arranged at intervals in a circumferential direction on the other of the fixed part and the rotating part, the number of which is greater than the number of channels, and which transmits signals of the plurality of channels; a switching unit that assigns the signals of the plurality of channels output from the signal generating unit to each transmission medium; Equipped with The switching unit is When any one of the plurality of transmission media passes near a separation portion between two circumferentially adjacent receiving media, a signal transmitted from the transmission medium to the two receiving media is switched to a signal of the same channel; For two transmission media facing two circumferentially adjacent receiving media, a signal output to one of the two transmission media is stopped or relatively attenuated. Wireless communication system.

2. When the number of transmission media is (N+1), the (N+1) transmission media as the plurality of transmission media are arranged at equal intervals in the circumferential direction, When an angle between the one transmission medium and a terminal end of a receiving medium facing the one transmission medium is 180 / {N(N+1)} degrees or less, the switching unit stops or relatively attenuates a signal output to the one transmission medium.

10. The wireless communication system of claim 1.

3. the receiving communication device, N receivers for processing N-channel signals as the plurality of channel signals received by the plurality of receiving media; and One ends of the plurality of receiving media are terminated, and 2N receiving media are arranged in a ring so that the ends of the receiving media are adjacent to each other; the other ends of the 2N receiving media as the plurality of receiving media are connected to the N receivers, respectively.

3. The wireless communication system according to claim 2.

4. the receiving communication device, a plurality of receivers for processing the signals of the plurality of channels received by the plurality of receiving media; and With respect to two transmission media facing two receiving media adjacent to each other in the circumferential direction, the switching unit stops or relatively attenuates a signal output to one of the two transmission media in accordance with a propagation length to one receiver provided in the two receiving media.

10. The wireless communication system of claim 1.

5. Each receiver is provided on two adjacent receiving media in the circumferential direction, a combiner for combining the signals of the channels received by the two receiving media; a comparator for converting an analog signal output from the multiplexer into a digital signal; 5. The wireless communication system according to claim 3, further comprising:

6. the transmitting communication device is disposed on the fixed part, the receiving communication device is disposed on the rotating part, the signal generation unit is a console device of the X-ray CT device or a device connected to the console device, the data is a control signal for the rotating unit transmitted by the console device; 3. The wireless communication system according to claim 1.

7. the transmitting communication device is disposed on the rotating part, the receiving communication device is disposed on the fixed part, the signal generation unit is a data collection device of an X-ray CT device or a device connected to a data collection device, the data is an X-ray signal collected by the data collection device; 3. The wireless communication system according to claim 1.

8. a rotating unit having an X-ray tube, an X-ray detector that detects X-rays emitted from the X-ray tube, and a data acquisition device that collects X-ray signals detected by the X-ray detector; a fixed part having a rotation mechanism for rotating the rotating part; a signal generating unit that divides data and outputs signals of multiple channels; a receiving communication device in which a plurality of receiving media are arranged at intervals along a circumferential direction on one of the fixed part and the rotating part, and which receives signals of the plurality of channels; a transmitter communication device in which a plurality of transmission media are arranged at intervals in a circumferential direction on the other of the fixed part and the rotating part, the number of which is greater than the number of channels, and which transmits signals of the plurality of channels; a switching unit that assigns the signals of the plurality of channels output from the signal generating unit to each transmission medium; Equipped with The switching unit is When any one of the plurality of transmission media passes near a separation portion between two circumferentially adjacent receiving media, a signal transmitted from the transmission medium to the two receiving media is switched to a signal of the same channel; For two transmission media facing two circumferentially adjacent receiving media, a signal output to one of the two transmission media is stopped or relatively attenuated. X-ray CT device.

9. a first transmitter communication device as the transmitter communication device is disposed in the fixed unit; a first receiver-side communication device as the receiver-side communication device is disposed on the rotating part; the signal generation unit is a console device of the X-ray CT device or a device connected to the console device, the data is a control signal for the rotating unit transmitted by the console device, a second transmitting communication device disposed in the rotating part and configured to transmit the X-ray signal collected by the data collecting device to a second receiving communication device in the fixed part, the second transmitting communication device being disposed in the ring in which the first receiving communication device is disposed; The X-ray CT apparatus according to claim 8.

10. a receiving communication device in which a plurality of receiving media are arranged at intervals in the circumferential direction on one of the fixed unit and the rotating unit, and the receiving communication device receives the signals of the plurality of channels; and a transmitting communication device in which a plurality of transmitting media are arranged at intervals in the circumferential direction on the other of the fixed unit and the rotating unit, the number of transmitting media being greater than the number of channels, and the transmitting communication device transmits the signals of the plurality of channels, and the number of transmitting media is (N+1), where (N+1) transmission media are arranged at equal intervals in the circumferential direction, assigning the signals of the plurality of channels output from the signal generating unit to each transmission medium; When any one of the plurality of transmission media passes near a separation portion between two circumferentially adjacent receiving media, a signal transmitted from the transmission medium to the two receiving media is switched to a signal of the same channel; For two transmission media facing two circumferentially adjacent receiving media, when the angle between one of the two transmission media and the terminal end of the receiving medium facing the one transmission medium is 180 / {N(N+1)} degrees or less, the signal output to the one transmission medium is stopped or relatively attenuated. Communication control method.

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