Communication device and communication system

Abstract

To enable reducing communication errors by firmly fixing substrates.SOLUTION: A communication device has a first substrate having a first transmission line, a metal part that functions as a ground with respect to the first substrate and is arranged spaced apart from the first transmission line, and a first termination circuit for terminating the first transmission line. The first substrate is fixed to any one of surfaces of the metal part other than a surface on which the first transmission line is located.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to a communication device and a communication system.

Background Art

[0002] A communication system that performs wireless communication using electromagnetic field coupling between adjacent devices is known. For example, in a swiveling movable part such as a robot arm part or a network camera, by performing wireless data transmission, it is possible to reduce cable wear and realize free swiveling.

[0003] Patent Document 1 discloses an information communication system having a first information communication device and a second information communication device. The first information communication device has a first non-contact power transmission coil and a first proximity wireless communication antenna formed coaxially with the first non-contact power transmission coil. The second information communication device has a second non-contact power transmission coil corresponding to the first non-contact power transmission coil and a second proximity wireless communication antenna formed coaxially with the second non-contact power transmission coil and corresponding to the first proximity wireless communication antenna.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, when the distance between the first information communication device and the second information communication device varies, the communication characteristics change, and there is a possibility of communication errors. Also, at the termination end, if the metal parts functioning as resistance and ground are not stably conductive, the reflection characteristics change, and the possibility of communication errors near the termination end increases.

[0006] The purpose of this disclosure is to enable robust mounting of the substrate and reduction of communication errors. [Means for solving the problem]

[0007] The communication device comprises a first substrate having a first transmission line, a metal part that functions as ground to the first substrate and is positioned with a space between it and the first transmission line, and a first termination circuit for terminating the first transmission line, wherein the first substrate is fixed to any of the metal parts other than the side on which the first transmission line is located. [Effects of the Invention]

[0008] According to this disclosure, the substrate can be securely fixed and communication errors can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of the configuration of a communication device according to the first embodiment. [Figure 2] This figure shows an example of the configuration of a communication device according to the second embodiment. [Figure 3] This figure shows an example of the configuration of a communication device according to the second embodiment. [Figure 4] This figure shows an example of the configuration of a communication device according to the second embodiment. [Modes for carrying out the invention]

[0010] A preferred embodiment will be described below with reference to the drawings. (First Embodiment) Figure 1(a) is a cross-sectional view showing an example of the configuration of the communication system 10 according to the first embodiment, and Figure 1(b) is a perspective view showing an example of the configuration of the communication system 10 according to the first embodiment. The communication system 10 includes a transmitting communication device 100 and a receiving communication device 200.

[0011] Communication devices 100 and 200 communicate wirelessly with each other using electromagnetic field coupling between transmission lines, as described later. In this embodiment, electromagnetic field coupling includes both electric field coupling and magnetic field coupling. That is, wireless communication between transmission lines may be performed by electric field coupling, by magnetic field coupling, or by both electric field coupling and magnetic field coupling.

[0012] First, let's describe the transmitting communication device 100 shown in Figure 1(a). The communication device 100 has a long configuration along the direction perpendicular to the plane of the paper as shown in Figure 1(a). The communication device 100 has a circuit board 101, a metal part 104, and a fixing member 105.

[0013] The substrate 101 is a flexible printed circuit board. The substrate 101 is made of materials such as polyimide, polyester, or liquid crystal polymer. The substrate 101 has flat top and bottom surfaces and is flexible in directions perpendicular to these surfaces. In this embodiment, the communication device 100 has two substrates 101 arranged adjacently in parallel along its longitudinal direction. However, the communication device 100 may have three or more substrates 101 arranged adjacently in parallel, or multiple substrates 101 may be integrated into a single unit.

[0014] The substrate 101 has transmission lines 102 and 103. Transmission lines 102 and 103 are formed as patterns on the substrate 101. Transmission lines 102 and 103 are transmitting transmission lines that transmit radio signals to transmission lines 202 and 203 of the receiving communication device 200, respectively. Transmission lines 102 and 103 function as transmitting couplers that transmit radio signals.

[0015] The transmission lines 102 and 103 are linear conductor members. For example, copper is used for the transmission lines 102 and 103. In this embodiment, the transmission lines 102 and 103 each constitute a differential transmission line by arranging two linear conductor members in parallel along the longitudinal direction on a single substrate 101. Note that the configuration is not limited to each substrate 101 having its own transmission line; a single substrate 101 may have both transmission lines 102 and 103.

[0016] The metal part 104 is a component that serves as the reference potential in the transmission lines 102 and 103. The metal part 104 functions as the ground potential relative to the substrate 101. The metal part 104 is positioned with respect to the transmission lines 102 and 103, with space between them. Specifically, the metal part 104 has a roughly U-shaped or V-shaped cross-section, with a space formed in the center in the width direction, and both ends in the width direction connected to the substrate 101. In this embodiment, the communication device 100 has two metal parts 104 arranged in parallel adjacent to each other along the longitudinal direction. However, three or more metal parts 104 may be arranged in parallel adjacent to each other, or multiple metal parts 104 may be formed as a single unit.

[0017] The substrate 101 is connected to the metal part 104 by a fixing member 105 on the sides other than the side on which the substrate 201 is located, as viewed from the metal part 104. This minimizes the distance between the substrate 101 and the substrate 201, allowing the substrate 101 to be securely fixed while increasing the strength of the wireless communication signal. The substrate 101 is also bonded to the metal part 104 via an adhesive 107. Any material placed between the substrate 101 and the metal part 104, such as the adhesive 107, can also be used on the side on which the substrate 201 is located, as viewed from the metal part 104. In this example, the substrate 101 is fixed to three sides of the metal part 104 using the fixing member 105 and the adhesive 107, but any combination of two or more sides is acceptable.

[0018] Next, the receiving-side communication device 200 in FIG. 1(a) will be described. The receiving-side communication device 200 has a configuration along the direction perpendicular to the paper surface shown in FIG. 1(a). The communication device 200 has a substrate 201. The substrate 201 is a flexible printed substrate having flexibility or a rigid substrate. For the substrate 201, materials such as polyimide, polyester, liquid crystal polymer, or FR-4 are used, for example. The upper and lower surfaces of the substrate 201 are flat. The substrate 201 is arranged at an interval from the transmitting-side communication device 100. Specifically, the substrate 201 is arranged on the opposite side of the metal portion 104 with respect to the substrate 101 of the communication device 100, with a space therebetween from the substrate 101. Further, the substrate 201 is configured to be movable along the parallel direction, that is, the direction perpendicular to the paper surface, with respect to the substrate 101.

[0019] The substrate 201 has transmission lines 202 and 203. The transmission lines 202 and 203 are formed as patterns on the substrate 201. The transmission lines 202 and 203 are receiving-side transmission lines that receive radio signals from the transmission lines 102 and 103 of the communication device 100, respectively, by electromagnetic field coupling. When viewed along the vertical direction, the transmission line 202 and the transmission line 102 overlap at least partially, and the transmission line 203 and the transmission line 103 overlap at least partially.

[0020] When the substrate 201 moves parallel to the substrate 101, the transmission line 202 moves along the longitudinal direction of the transmission line 102, and the transmission line 203 moves along the longitudinal direction of the transmission line 103. The transmission line 202 receives a wireless signal from the transmission line 102, and the transmission line 203 receives a wireless signal from the transmission line 103. The transmission lines 202 and 203 function as receiving couplers for receiving wireless signals. With such a configuration, wireless communication can be performed between the transmission lines 102 and 103 and the transmission lines 202 and 203 even while the substrate 201 is moving relative to the substrate 101. The transmission lines 202 and 203 in the present embodiment each constitute a differential transmission line by arranging two linear conductor members in parallel along the longitudinal direction on one substrate 201. Note that the present invention is not limited to a configuration in which each substrate 201 has a transmission line, and one substrate 201 may have a plurality of transmission lines 202 and 203.

[0021] FIG. 1(b) is a diagram showing a perspective view of FIG. 1(a) and the connection relationship between the differential transmission buffers 109 and 112 and the termination resistors 110. The communication device 100 includes signal sources 108 and 111, differential transmission buffers 109 and 112, and termination resistors 110. The data output from the signal sources 108 and 111 are input as differential signals to one ends of the transmission lines 102 and 103 via the differential transmission buffers 109 and 112 connected to one ends of the transmission lines 102 and 103, respectively. The differential transmission buffers 109 and 112 each input the output data of the signal sources 108 and 111 and output a differential signal to one ends of the transmission lines 102 and 103. The other ends of the transmission lines 102 and 103 are each terminated with a termination resistor 110 that is substantially equal to the differential impedance of the transmission lines 102 and 103. The two termination resistors 110 include a first and a second termination resistor 110. The first termination resistor 110 is connected between the termination ends of the two transmission lines 102. Also, the second termination resistor 110 is connected between the termination ends of the two transmission lines 103. The two termination resistors 110 are provided on the substrate 101.

[0022] The communication device 200 includes comparators 204 and 205. The differential signals output from one end of the transmission lines 202 and 203 are waveform-shaped by comparators 204 and 205, respectively, and then detected as received signals. Comparators 204 and 205 each waveform-shape the differential signals output from one end of the transmission lines 202 and 203 and output them as received signals. The configuration on the transmission line 203 side is the same as on the transmission line 202 side.

[0023] In the embodiments described above, the case where each transmission line is a differential microstrip line was explained, but the invention is not limited to this case. For example, the transmission lines 202 and 203 of the receiving communication device 200 may be capacitive transmission lines with open ends, or short-circuited inductive transmission lines.

[0024] Furthermore, in the embodiments described above, transmission lines 102 and 103 function as a transmitting coupler for transmitting wireless signals, and transmission lines 202 and 203 function as a receiving coupler for receiving wireless signals. However, the embodiments are not limited to this case. Because the directional coupler consisting of a transmitting coupler and a receiving coupler is reversible, the transmitting side and the receiving side can be swapped by changing the circuits connected to transmission lines 102 and 103 and the circuits connected to transmission lines 202 and 203. This ability to swap the transmitting side and the receiving side is also true in the embodiments described below.

[0025] According to this embodiment, the substrate 101 is connected to the metal part 104 by a fixing member 105. This minimizes the distance between the substrate 101 and the substrate 201, allowing the substrate 101 to be securely fixed while increasing the strength of the wireless communication signal. This suppresses fluctuations in the distance between the substrate 101 and the substrate 201, thereby suppressing fluctuations in communication characteristics and reducing communication errors.

[0026] As described above, the communication system 10 includes a communication device 100 and another communication device 200 that performs wireless communication with the communication device 100. The communication device 200 has a substrate 201 having transmission lines 202 and 203.

[0027] The communication device 100 includes a circuit board 101, a metal part 104, and a termination resistor 110. The circuit board 101 has transmission lines 102 and 103. The metal part 104 functions as ground to the circuit board 101 and is positioned between it and the transmission lines 102 and 103 with space between them. The termination resistor 110 is a termination circuit that terminates the transmission lines 102 and 103. The circuit board 101 is fixed to one of the sides of the metal part 104 other than the side on which the transmission lines 102 and 103 are located. The termination resistor 110 is connected between the two transmission lines 102. Another termination resistor 110 is connected between the two transmission lines 103.

[0028] A signal source 108 is connected to transmission line 102 via a differential transmit buffer 109. A signal source 111 is connected to transmission line 103 via a differential transmit buffer 112. Transmission lines 102 and 103 perform wireless communication with other communication devices 200. The substrate 101 is, for example, a flexible printed circuit board.

[0029] The substrate 101 is fixed to the metal part 104 by metal, fasteners, conductive adhesive, and conductive tape, or a combination thereof. The communication device 100 is used, for example, for communication between a network camera or a robot.

[0030] According to this embodiment, the substrate 101 can be securely fixed, and communication errors can be reduced.

[0031] (Second embodiment) Next, the termination structure of the transmission line according to the second embodiment will be described. The differences between the second embodiment and the first embodiment will be described below.

[0032] Figure 2 is a perspective view showing an example of the configuration of the communication system 10 according to the second embodiment. The communication system 10 in Figure 2 differs from the communication system 10 in Figure 1(b) in that the substrates 301, 401 and the metal part 304 form a square ring shape. In the communication system 10 in Figure 2, signals output from two signal sources 311 and 411 are input to their respective differential transmission lines 302 and 402, and the terminations of the differential transmission lines 302 and 402 face each other. With this structure, the differential transmission line 502 on the receiving side can move in the circumferential direction of the square ring shape of the differential transmission lines 302 and 402 on the transmitting side, so that electromagnetic field communication can be performed while moving in the circumferential direction. This embodiment is described assuming the space between the arms and hands of an arm robot, but it is not limited to arm robots, and can be applied to any rotating network camera, inter-device interface, or interface within a device.

[0033] The transmitting communication device 100 includes circuit boards 301 and 401, differential transmission lines 302 and 402, a metal part 304, a termination resistor 310, signal sources 311 and 411, and differential transmission buffers 312 and 412. The receiving communication device 200 includes a circuit board 501 and a differential transmission line 502. One receiving differential transmission line 502 selectively receives differential signals from the two transmitting differential transmission lines 302 and 402 by moving.

[0034] Substrates 301 and 401 each have differential transmission lines 302 and 402, which are two parallel linear conductor members. Differential transmission lines 302 and 402 are transmitting-side differential transmission lines that communicate non-contact with differential transmission line 502 on substrate 501 via electromagnetic field coupling. Substrates 301 and 401 do not need to be composed of multiple substrates and may be composed as a single unit. The metal part 304 is arranged to have a space between it and the differential transmission lines 302 and 402 and becomes the reference potential for the transmitting-side differential transmission lines 302 and 402. Here, the metal part 304 is in the shape of a square ring, but it does not need to be ring-shaped as long as the distance to the surface that becomes the reference potential for the differential transmission lines 302 and 402 is approximately constant.

[0035] The signals output from signal sources 311 and 411 are input as differential signals to one end of differential transmission lines 302 and 402, respectively, via differential transmit buffers 312 and 412 connected to one end of differential transmission lines 302 and 402. Differential transmit buffers 312 and 412 each receive the output signals from signal sources 311 and 411 and output the differential signals to one end of differential transmission lines 302 and 402.

[0036] A slit is provided in the metal part 304. The differential transmission lines 302, 402 and the differential transmit buffers 312, 412 are interconnected via the slit in the metal part 304. In addition, the differential transmission lines 302, 402 and the termination resistor 310 are interconnected via the slit in the metal part 304.

[0037] Note that the configuration is not limited to two signal sources and two differential transmission lines; it may also consist of one or three or more. Alternatively, a single signal source may be used, and signals may be input to each transmission line using a distributor or the like. The termination resistor 310 is positioned on the metal part (ground) 304 side relative to the surfaces of the substrates 301 and 401, and terminates each of the differential transmission lines 302 and 402.

[0038] The detailed structure of the termination sections of differential transmission lines 302 and 402 near the termination resistor 310 will be explained using Figures 3(a) to 3(c). Figure 3(a) is an oblique overhead view of the termination sections of differential transmission lines 302 and 402, Figure 3(b) is an oblique downward view of the termination sections of differential transmission lines 302 and 402, and Figure 3(c) is an exploded perspective view of the components shown in Figures 3(a) and 3(b).

[0039] A slit is provided in the metal part 304 near the termination resistor 310. The conductor parts 313 and 413 formed on the substrate are connected to the termination resistor 310 and function as ground. The conductor parts 313 and 413 are made of a material such as copper.

[0040] The conductors 313 and 413 are metal patterns formed on substrates 301 and 401, respectively. The substrates 301 and 401 and the conductors 313 and 413 are pulled out through a slit provided in the metal part 304. The pulled-out substrates 301 and 401 and the conductors 313 and 413 are connected to the metal part 304 by a fixing member 305 on the side opposite to the side where the substrate 501 is located, as viewed from the metal part 304. The metal part 304 and the conductors 313 and 413 are crimped together by the fixing member 305 and become electrically connected. This makes it possible to stably connect the conductors 313 and 413 to the metal part 304, which functions as a ground.

[0041] The four termination resistors 310 consist of first to fourth termination resistors 310. The first and second termination resistors 310 are provided on substrate 301. The third and fourth termination resistors 310 are provided on substrate 401.

[0042] The two transmission lines 302 consist of a first transmission line 302 and a second transmission line 302. The two conductor sections 313 consist of a first conductor section 313 and a second conductor section 313. The first termination resistor 310 is connected between the first transmission line 302 and the first conductor section 313. The second termination resistor 310 is connected between the second transmission line 302 and the second conductor section 313.

[0043] The two transmission lines 402 consist of a first transmission line 402 and a second transmission line 402. The two conductor sections 413 consist of a first conductor section 413 and a second conductor section 413. A third termination resistor 310 is connected between the first transmission line 402 and the first conductor section 413. A fourth termination resistor 310 is connected between the second transmission line 402 and the second conductor section 413.

[0044] Furthermore, it is desirable that the transmission lines 302 and 402 are not routed toward the slits in the metal part 304. This is because the different transmission lines 302 and 402 facing each other will couple, generating interference noise and degrading communication characteristics.

[0045] Figure 4 is a graph showing the reflection characteristics of the termination resistor 310 against its resistance value. The vertical axis represents the reflection coefficient [dB], and the horizontal axis represents the signal frequency [GHz]. Here, the differential impedance of the transmission line is approximately 100Ω. The reflection characteristics when the differential impedance of the termination resistor 310 is 100Ω are shown by the solid line, and the reflection characteristics when the differential impedance of the termination resistor 310 is set to ∞Ω (the termination resistor 310 is not conducting to the metal part 304) are shown by the dashed line. Thus, it can be seen that good reflection characteristics can be maintained by stabilizing the connection between the termination resistor 310 and the metal part 304 which functions as ground.

[0046] Thus, in a configuration where the signals of transmission lines 302 and 402 are branched in two or more directions, and the termination points of transmission lines 302 and 402 face each other, a slit is provided in the metal part 304, and the connection between the termination resistor 310 and the metal part 304 is made robust by the fixing member 305. This makes it possible to stabilize the reflection characteristics at the termination points of transmission lines 302 and 402.

[0047] Next, the effects of this embodiment will be explained. When a transmission line is formed on a general substrate, the attenuation in the high-frequency range due to dielectric loss is large, making it difficult to perform contactless communication with high-frequency signals over long distances. For example, in a microstrip transmission line where the substrate material is FR-4 and the substrate thickness is 1.6 mm, the attenuation characteristic when propagating over 1 m is attenuated by more than -20 dB in the frequency range of 6 GHz or higher. Also, if a fluororesin with relatively low dielectric loss is used as the substrate material, attenuation in the high-frequency band is suppressed, but the substrate becomes expensive.

[0048] Here, when a transmission line for transmitting signals is provided on a flexible substrate (hereinafter referred to as a flexible substrate), and the transmission line is formed with the upper surface of a metal (ground) approximately parallel to the flexible substrate as the ground plane, an air layer is formed between the transmission line and the ground plane. Therefore, dielectric loss is minimized, and a good transmission line capable of high-speed data communication over long distances can be formed. At this time, it is desirable that one end of the transmission line is connected to a signal source, and the other end of the transmission line is stably terminated with a resistance approximately equal to the characteristic impedance of the transmission line. Furthermore, in order to prevent displacement of the flexible substrate due to centrifugal force when a network camera or the like rotates, a method is needed to securely fix the flexible substrate while realizing wireless communication.

[0049] When the transmission line rotates, fluctuations in the distance between the transmitting and receiving transmission lines can alter communication characteristics and potentially cause communication errors. Furthermore, if the metal parts functioning as both termination resistors and ground at the end of the transmission line are not stably conductive, the reflection characteristics will change, increasing the likelihood of communication errors near the end of the transmission line.

[0050] According to this embodiment, the communication system 10 can reduce cable wear and enable free rotation by transmitting data wirelessly in swivelable parts such as the robot arm and network camera.

[0051] The substrates 301 and 401 are connected to the metal part 304 by the fixing member 305. This minimizes the distance between substrates 301, 401 and substrate 501, allowing for robust fixing of substrates 301 and 401 while increasing the strength of the wireless communication signal. This suppresses fluctuations in the distance between substrates 301, 401 and substrate 501, thereby suppressing fluctuations in communication characteristics and reducing communication errors.

[0052] Furthermore, by making the connection between the termination resistor 310 and the metal part 304 robust with the fixing member 305, the reflection characteristics at the termination of the transmission lines 302 and 402 can be stabilized, thereby suppressing communication errors.

[0053] As described above, the substrate 301 is fixed to any surface of the metal portion 304 other than the surface on which the transmission line 302 is located. The substrate 401 is also fixed to any surface of the metal portion 304 other than the surface on which the transmission line 402 is located. The metal portion 304 is, for example, ring-shaped.

[0054] The transmission line 302 is connected via a termination resistor 310 to any side of the metal part 304 other than the side on which the transmission line 302 is located. The transmission line 402 is connected via another termination resistor 310 to any side of the metal part 304 other than the side on which the transmission line 402 is located.

[0055] The terminating resistor 310 is connected between the transmission line 302 and the conductor section 313, terminating the transmission line 302. Another terminating resistor 310 is connected between the transmission line 402 and the conductor section 413, terminating the transmission line 402. The conductor section 313 is connected to any of the surfaces of the metal section 304 other than the surface on which the transmission line 302 is located. The conductor section 413 is connected to any of the surfaces of the metal section 304 other than the surface on which the transmission line 402 is located.

[0056] The metal part 304 has a slit. The substrates 301 and 401 are inserted into the slit of the metal part 304 and fixed to one of the surfaces of the metal part 304 other than the surface on which the transmission line 302 and transmission line 402 are located.

[0057] According to this embodiment, the substrates 301 and 401 can be securely fixed while stabilizing the reflection characteristics at the termination points of the transmission lines 302 and 402.

[0058] The present disclosure is not limited to the embodiments described above. Furthermore, not all combinations of features described in the embodiments described above are essential. Also, the contents described in the specification and drawings are illustrative and should not be considered limiting to the disclosure. In addition, various modifications (including organic combinations of each embodiment) are possible in accordance with the spirit of the disclosure and do not exclude them from the scope of the disclosure. That is, all configurations combining each of the embodiments described above and their variations are included in the disclosure. [Explanation of symbols]

[0059] 10: Communication system, 100: Transmitting communication device, 200: Receiving communication device, 101, 201, 301, 401: Circuit board, 102, 103, 202, 203, 302, 402: Transmission line, 104, 304: Metal part, 105: Fixing member, 107: Adhesive member, 108, 111, 311, 411: Signal source, 109, 112, 312, 412: Differential transmit buffer, 110, 310: Termination resistor, 204, 205: Comparator

Claims

1. A first substrate including a first transmission line having two conductors extending in a predetermined direction; a metal portion that functions as a ground for the first transmission line and has a slit; a first termination circuit that terminates the first transmission line; a portion of the first substrate is disposed in the slit of the metal portion; The communication device, wherein the first substrate has an overlapping portion in a direction perpendicular to the predetermined direction.

2. A communication device as described in claim 1, characterized in that the first substrate is fixed to the metal part by a fixing member.

3. The communication device described in claim 1 or 2, wherein the communication device communicates with another communication device opposite the communication device using electric field coupling or magnetic field coupling.

4. the first substrate further includes a first conductor portion; 4. The communication device according to claim 1, wherein the first conductor portion is connected to the first termination circuit.

5. The communication device described in Claim 3, characterized in that at least a portion of the first substrate is fixed on a surface different from a surface along which a second substrate of the other communication device in the metal part moves.

6. A communication device as described in any one of claims 1 to 5, characterized in that at least a portion of the metal part is fixed to the first substrate in a portion that overlaps in a direction perpendicular to the specified direction.

7. The communication device includes a third substrate having a second transmission line; 7. The communication device according to claim 1, further comprising a second termination circuit for terminating the second transmission line.

8. 8. The communication device according to claim 1, wherein a first signal source is connected to the first transmission line.

9. 9. The communication device according to claim 1, wherein the first substrate is a flexible printed circuit board.

10. A communication device as described in claim 3, wherein the first substrate is fixed by tape on a surface along which a second substrate of the other communication device in the metal part moves.

11. The communication device according to any one of claims 1 to 10, characterized in that the first substrate is fixed to the metal portion by any one or a combination of metal, fasteners, conductive adhesive, and conductive tape.

12. The communication device according to any one of claims 1 to 11, characterized in that the communication device is used for communication with a network camera or a robot.

13. A first substrate including a first transmission line having two conductors extending in a predetermined direction; a metal portion that functions as a ground for the first transmission line and has a slit; a first communication unit having a first termination circuit that terminates the first transmission line; a second communication unit that performs wireless communication with the first communication unit, a portion of the first substrate is disposed in the slit of the metal portion; A communication system, wherein the first substrate has an overlapping portion in a direction perpendicular to the predetermined direction.

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