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]

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

[0002] There are known communication systems that use electromagnetic coupling to perform wireless communication between nearby devices. For example, in rotating movable parts such as robot arms and network cameras, wireless data transmission can reduce cable wear and enable free rotation.

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

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-96612 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, fluctuations in the distance between the first information communication device and the second information communication device can change the communication characteristics, potentially resulting in communication errors. Furthermore, unless stable conduction is maintained between the resistor and the metal part that functions as the ground at the termination, reflection characteristics can change, increasing the likelihood of communication errors occurring near the termination.

[0006] An object of the present disclosure is to stably fix a substrate and reduce communication errors. [Means for solving the problem]

[0007] The communication device includes a first substrate including a first transmission line having two conductors extending in a predetermined direction; a portion spaced apart from the first substrate; Acts as the ground for the first transmission line do Metal parts and a fixing member that fixes the first substrate to the metal portion; Terminate the first transmission line Multiple endings end Resistance and and The first substrate comprises: The metal part The Litt In an inserted state, The first group Part of a board is in a direction perpendicular to the predetermined direction and the other portion of the first substrate. Overlap. [Effects of the Invention]

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

[0009] [Figure 1] 1 is a diagram illustrating an example of a configuration of a communication device according to a first embodiment. [Figure 2] FIG. 10 is a diagram illustrating an example of a configuration of a communication device according to a second embodiment. [Figure 3] FIG. 10 is a diagram illustrating an example of a configuration of a communication device according to a second embodiment. [Figure 4] FIG. 10 is a diagram illustrating an example of a configuration of a communication device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments will now be described with reference to the drawings. (First embodiment) Fig. 1(a) is a cross-sectional view showing an example of the configuration of a communication system 10 according to the first embodiment, and Fig. 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 communication device 100 on the transmitting side and a communication device 200 on the receiving side.

[0011] The communication devices 100 and 200 communicate wirelessly with each other using electromagnetic field coupling between transmission lines, which will be described later. Note that the electromagnetic field coupling in this embodiment includes both electric field coupling and magnetic field coupling. That is, the wireless communication between the transmission lines may be performed using electric field coupling, magnetic field coupling, or both electric field coupling and magnetic field coupling.

[0012] First, the transmitting communication device 100 in Fig. 1(a) will be described. The communication device 100 has a configuration that is elongated along the direction perpendicular to the plane of the paper shown in Fig. 1(a). The communication device 100 has a substrate 101, a metal part 104, and a fixing member 105.

[0013] The substrate 101 is a flexible printed circuit board that has flexibility. The substrate 101 is made of a material such as polyimide, polyester, or liquid crystal polymer. The substrate 101 has flat top and bottom surfaces and is flexible in directions perpendicular to the top and bottom surfaces. In the communication device 100 of this embodiment, two substrates 101 are arranged adjacent to each other in parallel along the longitudinal direction. However, the communication device 100 may have three or more substrates 101 arranged adjacent to each other in parallel, or may have multiple substrates 101 configured as an integrated unit.

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

[0015] The transmission lines 102 and 103 are linear conductor members. The transmission lines 102 and 103 are made of, for example, copper or other materials. In this embodiment, the transmission lines 102 and 103 are each configured as a transmission line for differential transmission, with two linear conductor members arranged in parallel along the longitudinal direction on one substrate 101. Note that the configuration is not limited to one in which each substrate 101 has its own transmission line, and one substrate 101 may have the transmission lines 102 and 103.

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

[0017] Substrate 101 is connected to metal portion 104 by fixing member 105 on a surface other than the surface on which substrate 201 is located as viewed from metal portion 104. This minimizes the distance between substrates 101 and 201, and enables substrate 101 to be securely fixed while increasing the strength of the wireless communication signal. Substrate 101 is also bonded to metal portion 104 via adhesive 107. An adhesive such as adhesive 107 that is disposed between substrate 101 and metal portion 104 can also be used on the surface on which substrate 201 is located as viewed from metal portion 104. Note that, although an example has been shown here in which substrate 101 is fixed to three surfaces of metal portion 104 using fixing member 105 and adhesive 107, any combination is possible as long as there are two or more surfaces.

[0018] Next, the receiving-side communication device 200 of FIG. 1(a) will be described. The receiving-side communication device 200 is configured 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 circuit board or a rigid substrate. The substrate 201 is made of a material such as polyimide, polyester, liquid crystal polymer, or FR-4. The top and bottom surfaces of the substrate 201 are flat. The substrate 201 is disposed with a gap between it and the transmitting-side communication device 100. Specifically, the substrate 201 is disposed on the opposite side of the metal part 104 with respect to the substrate 101 of the communication device 100, with a space between them. The substrate 201 is configured to be movable in a direction parallel to the substrate 101, i.e., along the direction perpendicular to the paper surface.

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

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

[0021] FIG. 1(b) is a perspective view of FIG. 1(a) and illustrates the connection relationship between differential transmit buffers 109 and 112 and a termination resistor 110. The communication device 100 includes signal sources 108 and 111, differential transmit buffers 109 and 112, and a termination resistor 110. Data output from the signal sources 108 and 111 is input as a differential signal to one end of the transmission lines 102 and 103 via differential transmit buffers 109 and 112 connected to one end of the transmission lines 102 and 103, respectively. The differential transmit buffers 109 and 112 receive the output data from the signal sources 108 and 111, respectively, and output the differential signal to one end of the transmission lines 102 and 103. The other ends of the transmission lines 102 and 103 are terminated by termination resistors 110 whose differential impedances are approximately equal to the differential impedances of the transmission lines 102 and 103, respectively. 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. 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] Communication device 200 has comparators 204 and 205. Differential signals output from one end of transmission lines 202 and 203 are waveform-shaped by comparators 204 and 205, respectively, and then detected as received signals. Comparators 204 and 205 waveform-shape the differential signals output from one end of transmission lines 202 and 203, respectively, and output the signals as received signals. Note that the transmission line 203 side has the same configuration as the transmission line 202 side.

[0023] In the above-described embodiment, the transmission lines are differential microstrip lines, but this is not limiting. For example, the transmission lines 202 and 203 of the receiving communication device 200 may be open-ended capacitive transmission lines or short-circuited inductive transmission lines.

[0024] In the above-described embodiment, the transmission lines 102 and 103 function as transmitting couplers for transmitting radio signals, and the transmission lines 202 and 203 function as receiving couplers for receiving radio signals. However, this is not a limitation. Because a directional coupler consisting of a transmitting coupler and a receiving coupler is reversible, the transmitting side and the receiving side can be interchanged by changing the circuits connected to the transmission lines 102 and 103 and the circuits connected to the transmission lines 202 and 203. This ability to interchange the transmitting side and the receiving side also applies to the following embodiments.

[0025] According to this embodiment, the substrate 101 is connected to the metal part 104 by the fixing member 105. This makes it possible to minimize the distance between the substrate 101 and the substrate 201, and to securely fix the substrate 101 while increasing the strength of the wireless communication signal. This makes it possible to suppress fluctuations in the distance between the substrate 101 and the substrate 201, suppress fluctuations in communication characteristics, and suppress communication errors.

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

[0027] The communication device 100 has a substrate 101, a metal part 104, and a termination resistor 110. The substrate 101 has transmission lines 102 and 103. The metal part 104 functions as a ground for the substrate 101 and is disposed between the transmission lines 102 and 103 with a space therebetween. The termination resistor 110 is a termination circuit that terminates the transmission lines 102 and 103. The substrate 101 is fixed to one of the surfaces of the metal part 104 other than the surface on which the transmission lines 102 and 103 are located. The termination resistor 110 is connected between the two transmission lines 102. The other termination resistor 110 is connected between the two transmission lines 103.

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

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

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

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

[0032] FIG. 2 is a perspective view showing an example of the configuration of a communication system 10 according to a second embodiment. The communication system 10 in FIG. 2 differs from the communication system 10 in FIG. 1(b) in that the substrates 301 and 401 and the metal part 304 form a square ring shape. In the communication system 10 in FIG. 2, signals output from two signal sources 311 and 411 are input to differential transmission lines 302 and 402, respectively, and the terminations of the differential transmission lines 302 and 402 face each other. This structure allows the differential transmission line 502 on the receiving side to move in the circumferential direction of the square ring shape of the differential transmission lines 302 and 402 on the transmitting side, thereby enabling electromagnetic field communication while moving in the circumferential direction. While this embodiment has been described assuming a section between the arms and hands of an arm robot, it is not limited to arm robots and is applicable to any application, such as a rotating network camera, or an interface between or within devices.

[0033] The transmitting communication device 100 has substrates 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 has a substrate 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] Substrate 301 and substrate 401 each have differential transmission lines 302 and 402, which are two linear conductor members arranged side by side. Differential transmission lines 302 and 402 are transmitting-side differential transmission lines that communicate contactlessly with differential transmission line 502 on substrate 501 through electromagnetic coupling. Note that substrates 301 and 401 do not need to be composed of multiple substrates and may be integrally formed. Metal portion 304 is disposed so as to have a space between it and differential transmission lines 302 and 402, and serves as a reference potential for transmitting-side differential transmission lines 302 and 402. Here, metal portion 304 has a square ring shape, but it does not need to be ring-shaped as long as the distance to the plane that serves as the reference potential for differential transmission lines 302 and 402 is approximately constant.

[0035] The signals output from the signal sources 311 and 411 are input as differential signals to one end of the differential transmission lines 302 and 402 via differential transmission buffers 312 and 412 connected to one end of the differential transmission lines 302 and 402, respectively. The differential transmission buffers 312 and 412 receive the output signals of the signal sources 311 and 411, respectively, and output the differential signals to one end of the 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 transmission buffers 312, 412 are connected to each other via the slit in the metal part 304. In addition, the differential transmission lines 302, 402 and the termination resistor 310 are connected to each other via the slit in the metal part 304.

[0037] The number of signal sources and differential transmission lines is not limited to two, but may be one or three or more. Also, a single signal source may be used, and signals may be input to each transmission line using a distributor or the like. Termination resistor 310 is arranged on the metal part (ground) 304 side of the surfaces of substrates 301 and 401, and terminates each of differential transmission lines 302 and 402.

[0038] The detailed structure of the termination portions of the differential transmission lines 302 and 402 near the termination resistor 310 will be described with reference to Figures 3(a) to 3(c). Figure 3(a) is a top oblique view of the termination portions of the differential transmission lines 302 and 402, Figure 3(b) is a bottom oblique view of the termination portions of the differential transmission lines 302 and 402, and Figure 3(c) is an exploded perspective view of the components of Figures 3(a) and 3(b).

[0039] The metal part 304 has a slit formed in the vicinity of 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] Conductor portions 313 and 413 are metal patterns formed on substrates 301 and 401, respectively. Substrates 301 and 401 and conductor portions 313 and 413 are pulled out through slits provided in metal portion 304. The pulled-out substrates 301 and 401 and conductor portions 313 and 413 are connected to metal portion 304 by fixing member 305 on the side of metal portion 304 opposite the side on which substrate 501 is located. Metal portion 304 and conductor portions 313 and 413 are crimped and electrically connected by fixing member 305. This allows conductor portions 313 and 413 to be stably connected to metal portion 304, which functions as ground.

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

[0042] The two transmission lines 302 include a first transmission line 302 and a second transmission line 302. The two conductor portions 313 include a first conductor portion 313 and a second conductor portion 313. The first termination resistor 310 is connected between the first transmission line 302 and the first conductor portion 313. The second termination resistor 310 is connected between the second transmission line 302 and the second conductor portion 313.

[0043] The two transmission lines 402 include a first transmission line 402 and a second transmission line 402. The two conductor portions 413 include a first conductor portion 413 and a second conductor portion 413. The third termination resistor 310 is connected between the first transmission line 402 and the first conductor portion 413. The fourth termination resistor 310 is connected between the second transmission line 402 and the second conductor portion 413.

[0044] At this time, it is desirable that the transmission lines 302 and 402 are not drawn toward the slit in the metal part 304. This is because if the different transmission lines 302 and 402 face each other, they will be coupled, causing interference noise and deteriorating communication characteristics.

[0045] FIG. 4 is a graph showing the reflection characteristics versus the resistance value of termination resistor 310. 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 100 Ω. The solid line represents the reflection characteristics when the differential impedance of termination resistor 310 is set to 100 Ω, and the dashed line represents the reflection characteristics when the differential impedance of termination resistor 310 is set to ∞ Ω (termination resistor 310 is non-conductive with respect to metal part 304). As such, it can be seen that good reflection characteristics can be maintained by stabilizing the connection state between termination resistor 310 and metal part 304, which functions as ground.

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

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

[0048] Here, when a transmission line for transmitting signals is provided on a flexible printed circuit board (hereinafter referred to as a flex board), and the top surface of a metal (ground) approximately parallel to the flex board is used as the ground plane, an air gap forms between the transmission line and the ground plane. This minimizes dielectric loss, enabling the formation of an excellent transmission line capable of high-speed data communication over long distances. In this case, it is desirable for one end of the transmission line to be connected to a signal source, and for the other end to be stably terminated with a resistance approximately equal to the characteristic impedance of the transmission line. Furthermore, to prevent displacement of the flex board due to centrifugal force when a network camera or other device is rotated, a method is needed to securely fix the flex board while still enabling wireless communication.

[0049] When turning, if the distance between the transmission line on the sending side and the transmission line on the receiving side changes, the communication characteristics may change, which may result in a communication error. Also, if there is no stable conduction between the metal part that functions as the termination resistor and the ground at the end of the transmission line, the reflection characteristics may change, increasing the possibility of a communication error occurring near the end of the transmission line.

[0050] According to this embodiment, the communication system 10 transmits data wirelessly in a swivelable part such as a robot arm or a network camera, thereby reducing cable wear and enabling free rotation.

[0051] Substrates 301 and 401 are connected to metal part 304 by fixing member 305. This makes it possible to minimize the distance between substrates 301, 401 and substrate 501, and to securely fix substrates 301 and 401 while increasing the strength of wireless communication signals. Fluctuations in the distance between substrates 301, 401 and substrate 501 can be suppressed, which in turn suppresses fluctuations in communication characteristics and communication errors.

[0052] Furthermore, by using fixing member 305 to make the connection between termination resistor 310 and metal part 304 more robust, the reflection characteristics at the terminations of transmission lines 302 and 402 can be stabilized, and communication errors can be suppressed.

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

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

[0055] Termination resistor 310 is connected between transmission line 302 and conductor portion 313, and terminates transmission line 302. Another termination resistor 310 is connected between transmission line 402 and conductor portion 413, and terminates transmission line 402. Conductor portion 313 is connected to one of the surfaces of metal portion 304 other than the surface on which transmission line 302 is located. Conductor portion 413 is connected to one of the surfaces of metal portion 304 other than the surface on which transmission line 402 is located.

[0056] Metal part 304 has slits. Substrates 301 and 401 are inserted into the slits of metal part 304 and fixed to one of the surfaces of metal part 304 other than the surface on which transmission lines 302 and 402 are located.

[0057] According to this embodiment, the substrates 301 and 401 can be firmly fixed, and the reflection characteristics at the terminations of the transmission lines 302 and 402 can be stabilized.

[0058] As mentioned above, the present disclosure is not limited to the above-described embodiments. Furthermore, not all of the combinations of features described in the above-described embodiments are necessarily required. Furthermore, the contents of the specification and drawings are merely examples and should not be considered as limiting the present disclosure. Furthermore, various modifications (including organic combinations of the respective embodiments) are possible based on the spirit of the present disclosure, and these are not excluded from the scope of the present disclosure. In other words, all configurations that combine the above-described embodiments and their modifications are also included in the present disclosure. [Explanation of symbols]

[0059] 10: communication system, 100: transmitting communication device, 200: receiving communication device, 101, 201, 301, 401: substrate, 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 transmission 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 is partly separated from the first substrate and functions as a ground for the first transmission line; a fixing member that fixes the first substrate to the metal portion; a plurality of termination resistors that terminate the first transmission line; the first substrate is inserted into a slit of the metal portion, A communication device, wherein a portion of the first substrate overlaps another portion of the first substrate in a direction perpendicular to the predetermined direction.

2. The communication device according to claim 1 , wherein the communication device communicates with another communication device that is opposite to the communication device by using electric field coupling or magnetic field coupling.

3. the first substrate further includes a first conductor portion; 3. The communication device according to claim 1, wherein the first conductor portion is connected to the plurality of termination resistors.

4. The communication device according to claim 2 , wherein at least a portion of the first substrate is fixed on a surface of the metal part that is different from a surface on which a second substrate of the other communication device moves.

5. 5. The communication device according to claim 1, wherein at least a portion of the first substrate is fixed to the metal portion in a portion that overlaps the first substrate in a direction perpendicular to the predetermined direction.

6. The communication device includes: a third substrate having a second transmission line; 6. The communication device according to claim 1, further comprising a plurality of other termination resistors for terminating the second transmission line.

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

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

9. The communication device according to claim 2 , wherein the first board is fixed with tape on a surface of the metal part on which the second board of the other communication device moves.

10. The communication device according to any one of claims 1 to 9, characterized in that the first substrate is fixed to the metal part by any one or a combination of metal, a fastener, a conductive adhesive, and a conductive tape.

11. The communication device according to any one of claims 1 to 10, characterized in that the communication device is used for communication with a network camera or a robot.

12. a first substrate including a first transmission line having two conductors extending in a predetermined direction; a metal portion that is partly separated from the first substrate and functions as a ground for the first transmission line; a fixing member that fixes the first substrate to the metal portion; a first communication unit having a plurality of termination resistors that terminate the first transmission line; a second communication unit that performs wireless communication with the first communication unit, the first substrate is inserted into a slit of the metal portion, A communication system, characterized in that a portion of the first substrate overlaps another portion of the first substrate in a direction perpendicular to the predetermined direction.

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