Communication device and communication system

Abstract

To provide a technique that can match the impedance between a transmitter and a terminator and achieve improvement in communication quality.SOLUTION: A transmission line 120 includes: a first transmission line part 121 that has a first characteristic impedance; second transmission line parts 122 and 124 that are arranged between the first transmission line part 121 and an input signal source 110 as a transmitter and between the first transmission line part 121 and a terminator 130, and has a second characteristic impedance different from the first characteristic impedance; and third transmission line parts 123 and 125 that are arranged between the first transmission line part 121 and the second transmission line parts 122 and 124, have a third characteristic impedance between the first characteristic impedance and the second characteristic impedance in a lengthwise direction L, and include a structure in which the line width in a width direction W gradually changes.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 transmit large volumes of data within or between adjacent devices by applying wireless communication technology using electromagnetic coupling. For example, in production systems and robotic devices, wireless communication between mechanical moving parts and fixed parts is used to reduce cable wear and enable free rotation.

[0003] Patent Document 1 describes a technology for wireless communication between a differential transmission line having a signal source (transmitter) that outputs a data signal and a terminator, and a near-field probe on the receiving device side that moves relatively at a fixed distance from the differential transmission line. The differential transmission line described in Patent Document 1 is designed to achieve impedance matching with the signal source, and the terminator is also matched and terminated. Patent Document 1 shows that this makes wideband response possible. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6304906 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there is an increasing need to transmit large amounts of data such as image data. For this reason, for example, a method is conceivable in which a plurality of transmission lines are arranged at a distance from each other, data to be transmitted is divided into a plurality of channels and output, and the data is received by a plurality of receiving electrodes corresponding to each transmission line. However, when a plurality of transmission lines are arranged and used in the configuration described in Patent Document 1, for example, if the distance between adjacent transmission lines is short, interference occurs between the transmission lines and communication quality deteriorates, so a certain amount of mounting space is required to prevent interference. In addition, it is possible to reduce the mounting space by narrowing (reducing) the transmission line width. However, in that case, the characteristic impedance of the transmission line becomes large, and impedance mismatch occurs between the transmitter and the terminator, which are signal sources located at both ends of the transmission line, and signal quality (communication quality) deteriorates.

[0006] Here, consider the case where such wireless communication technology is used in a situation where there is a lot of noise due to the surroundings or where the electromagnetic coupling between the transmission line and the receiving electrode is weak. In this case, it is possible to increase the signal strength by making the transmission line wider (larger) to ensure communication quality. However, in that case, the characteristic impedance of the transmission line becomes smaller, causing an impedance mismatch between the transmitter (signal source) and the terminator, resulting in a deterioration of communication quality.

[0007] In this way, when designing a transmission line to suit the mounting conditions, there is a problem that communication quality deteriorates due to impedance mismatch between the transmitter (signal source) and the terminator.

[0008] The present disclosure has been made in consideration of such problems, and has an object to provide a technique that can achieve impedance matching between a transmitter and a terminator and improve communication quality. [Means for solving the problem]

[0009] A communication device of the present disclosure includes a transmission line for communicating with a communication electrode of another communication device through electromagnetic coupling, a transmitter connected to one end of the transmission line, and a terminator connected to the other end of the transmission line different from the one end, wherein the transmission line includes: a first transmission line section having a first characteristic impedance; a second transmission line section arranged between at least one of between the first transmission line section and the transmitter and between the first transmission line section and the terminator, and having a second characteristic impedance different from the first characteristic impedance; and a third transmission line section arranged between the first transmission line section and the second transmission line section, and having a structure in which a line width changes stepwise, the third transmission line section having a third characteristic impedance between the first characteristic impedance and the second characteristic impedance in a predetermined direction transitioning from the first transmission line section to the second transmission line section. Effect of the Invention

[0010] According to the present disclosure, impedance matching between a transmitter and a terminator can be achieved, thereby improving communication quality. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a first example of a schematic configuration of a wireless communication system according to a first embodiment of the present disclosure. [Diagram 2] 2 is a diagram illustrating a second example of a schematic configuration of a wireless communication system according to a first embodiment of the present disclosure. FIG. [Diagram 3] FIG. 13 is a diagram showing the effect of characteristic impedance transformation by a quarter-wave transformer in terms of reflection characteristics. [Figure 4] 11A and 11B are diagrams illustrating changes in reflection characteristics depending on whether or not a characteristic impedance conversion line portion is present, and changes in transfer characteristics to a receiving electrode depending on whether or not a characteristic impedance conversion line portion is present. [Diagram 5] FIG. 10 illustrates the first embodiment of the present disclosure and is a diagram showing the influence of the transfer characteristic on the receiving electrode depending on the position of the receiving electrode. [Figure 6] FIG. 11 is a diagram illustrating an example of a schematic configuration of a wireless communication system according to a second embodiment of the present disclosure. [Figure 7] 13 is a diagram showing reflection characteristics and transfer characteristics to a receiving electrode in a wireless communication system according to a second embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, modes (embodiments) for carrying out the present disclosure will be described with reference to the drawings.

[0013] (First embodiment) First, a first embodiment of the present disclosure will be described.

[0014] 1 is a diagram showing a first example of a schematic configuration of a wireless communication system 10 according to the first embodiment of the present disclosure. As shown in FIG. 1, the wireless communication system 10 includes a transmitting device 100, a receiving device 200, and a mobile control device 300.

[0015] The transmitting device 100 is a communication device that performs wireless communication with the receiving device 200, which is another communication device, by electromagnetic field coupling. As shown in FIG. 1, the transmitting device 100 has an input signal source 110, a transmission line 120, a terminator 130, and a reference potential surface 140. The receiving device 200 is another communication device that has a receiving electrode 210, which is a communication electrode for performing wireless communication with the transmitting device 100, and a receiving circuit 220 that processes a signal detected by the receiving electrode 210 and generates an output signal. The movement control device 300 is a movement control device that relatively moves the transmitting device 100 and the receiving device 200 in the length direction L (predetermined direction) of the transmission line 120. In this embodiment, the movement control device 300 adopts a form in which the receiving device 200 moves in the length direction L of the transmission line 120, as shown by a solid line in FIG. 1. In the present disclosure, the movement control device 300 is not limited to a form in which the receiving device 200 is moved in the length direction L of the transmission line 120, but also includes a form in which the transmitting device 100 is moved in the length direction L of the transmission line 120, for example, as shown by the dotted line in FIG. 1.

[0016] The internal configuration of the transmitting device 100 will be described below. The input signal source 110 is a transmitter electrically connected to one end of the transmission line 120. The transmission line 120 is a transmission line for communicating with a receiving electrode 210 of the receiving device 200 by electromagnetic field coupling. The terminator 130 is a terminator electrically connected to the other end of the transmission line 120 different from the one end (the end to which the input signal source 110 is connected). The reference potential surface 140 is a ground surface that serves as a reference potential for the transmission line 120.

[0017] Next, the transmission line 120 of the transmitting device 100 will be described in detail. The transmission line 120 includes a region 120a where the line width in the width direction W is variable, a region 120b where the line width in the width direction W is determined by the input signal source 110, and a region 120c between the regions 120a and 120b where the line width in the width direction W changes gradually (in steps). Here, in this embodiment, the region 120a of the transmission line 120 is a transmission line section 121, the region 120b of the transmission line 120 is a transmission line section 122, and the region 120c of the transmission line 120 is a transmission line section 123. Furthermore, the transmission line 120 includes a region 120d where the line width in the width direction W is determined by the terminator 130, and a region 120e between the regions 120a and 120d where the line width in the width direction W changes gradually (in steps). In this embodiment, the region 120d of the transmission line 120 is referred to as a transmission line portion 124, and the region 120e of the transmission line 120 is referred to as a transmission line portion 125.

[0018] The transmission line portion 121 is a first transmission line portion having a first characteristic impedance. The transmission line portion 122 is a transmission line portion disposed between the transmission line portion 121 and the input signal source 110, which is a transmitter, and has a characteristic impedance different from the first characteristic impedance. The transmission line portion 124 is a transmission line portion disposed between the transmission line portion 121 and the terminator 130 and has a characteristic impedance different from the first characteristic impedance. In the present disclosure, at least one of the transmission line portion 122 and the transmission line portion 124 is a second transmission line portion, and the characteristic impedance of the second transmission line portion is a second characteristic impedance. The transmission line portion 123 is a transmission line portion disposed between the transmission line portion 121 and the transmission line portion 122, and has a structure in which the line width in the width direction W changes stepwise in the length direction L, which is a predetermined direction from the transmission line portion 121 to the transmission line portion 122. Moreover, the transmission line portion 125 is disposed between the transmission line portion 121 and the transmission line portion 124, and is a transmission line portion having a structure in which the line width in the width direction W changes stepwise in the length direction L, which is a predetermined direction from the transmission line portion 121 to the transmission line portion 124. The structure in which the line width of the transmission line portion 123 and the transmission line portion 125 changes gradually includes a tapered structure (a structure that changes at an incline) and a structure that changes in a step-like manner. In this embodiment, the transmission line portion 123 and the transmission line portion 125 are third transmission line portions having a third characteristic impedance between the first characteristic impedance and the second characteristic impedance. Specifically, the third characteristic impedance is larger than the second characteristic impedance described above and smaller than the first characteristic impedance described above. Moreover, the transmission line portion 123 and the transmission line portion 125 each correspond to a characteristic impedance conversion line portion in which the line width changes depending on the line width in the width direction W of the transmission line portions at both ends.

[0019] The transmission line portion 121 has a first line width in the width direction W. The transmission line portion 122 and the transmission line portion 124 have a second line width in the width direction W that is larger than the first line width of the transmission line portion 121. The transmission line portion 123 and the transmission line portion 125 have a line width that is between the first line width of the transmission line portion 121 and the second line width of the transmission line portion 122 and the transmission line portion 124 in the width direction W and that changes stepwise in the length direction L (predetermined direction) of the transmission line 120. Here, the line width of the transmission line portion 122 is a line width that provides a characteristic impedance equal to that of the input signal source 110. Moreover, the line width of the transmission line portion 124 is a line width that provides a characteristic impedance equal to that of the terminator 130.

[0020] The length of the transmission line portion 123 and the transmission line portion 125 in the longitudinal direction L is determined by the data rate to be transmitted.

[0021] In the wireless communication system 10 according to this embodiment, wireless communication is performed by electromagnetically coupling the transmission line 120 and the receiving electrode 210. The receiving device 200 moves relatively along the transmission line 120 while maintaining a certain distance on the transmission line 120. The movement is achieved by a movement control device 300 such as a motor. The line width of the receiving electrode 210 is determined so as to enable communication with the transmission line 120, and there is no particular limit to the width.

[0022] Fig. 2 is a diagram showing a second example of a schematic configuration of a wireless communication system 20 according to the first embodiment of the present disclosure. In Fig. 2, the same reference numerals are used for configurations having the same functions as those shown in Fig. 1, and detailed descriptions thereof will be omitted.

[0023] The wireless communication system 20 shown in FIG. 2(a) is a system in which the transmission line 120 of the wireless communication system 10 shown in FIG. 1 is realized by a differential transmission line, and a part of the area of ​​the transmission device 100 shown in FIG. 1 is used as the transmission device 101. Specifically, the transmission device 101 shown in FIG. 2(a) includes an area 120a which is a part of the transmission line part 121, an area 120b which is a part of the transmission line part 122, and an area 120c which is a part of the transmission line part 123 in the transmission line 120. That is, the transmission device 101 corresponds to an area near the transmission line 120 connected to the input signal source 110 shown in FIG. 1. The transmission device 101 has a conductor 141 which serves as a reference potential including the reference potential surface 140 shown in FIG. 1, and a substrate 150. The space between the conductor 141 and the substrate 150 is air. The substrate 150 has a transmission line (differential transmission line) 120. 2, the characteristic impedance of transmission line portion 121 located in region 120a where the line width in the width direction W is variable is set to 160 Ω. Also, the characteristic impedance of transmission line portion 122 located in region 120b where the line width in the width direction W is determined by input signal source 110 is set to 100 Ω.

[0024] The transmission line section 123 (which may include the transmission line section 125 in FIG. 1) corresponding to the characteristic impedance conversion line section in this embodiment utilizes the principle of a quarter-wave transformer. The transmission line section 123 of the wireless communication system 20 shown in FIG. 2 is a characteristic impedance conversion line section in which a quarter-wave transformer is tapered. Here, the quarter-wave transformer converts the characteristic impedance when connecting transmission lines with different characteristic impedances by connecting a line having a length that is a quarter of the wavelength of the carrier frequency.

[0025] In this embodiment, as shown in Fig. 2(a), for example, the transmission line 120 has a line width in the width direction W that is wider than the width of the receiving electrode 210, which is a communication electrode of the receiving device 200. By adopting such a configuration, it is possible to always maintain the electromagnetic coupling with the receiving electrode 210 at a constant level or higher at any position on the transmission line 120, and it is possible to maintain a constant signal strength. In the example shown in Fig. 2(a), a differential transmission line is used as the transmission line 120, and therefore the receiving electrode 210 is provided so as to be disposed opposite the differential transmission line.

[0026] Fig. 2(b) is a side view of the wireless communication system 20 shown in Fig. 2(a). In region 120a shown in Fig. 2(b), a transmission line portion 121 having a differential impedance of 160Ω exists. In region 120c shown in Fig. 2(b), a transmission line portion 123 corresponding to a characteristic impedance conversion line portion exists. In region 120b shown in Fig. 2(b), a transmission line portion 122 having a differential impedance of 100Ω exists.

[0027] FIG. 3 is a diagram showing the effect of characteristic impedance transformation by a quarter-wave transformer in terms of reflection characteristics.

[0028] Reflection characteristic 313 is the reflection characteristic of the transmission line when a differential impedance of 100 Ω is directly fed to a transmission line with a differential impedance of 160 Ω without using a quarter-wave transformer. In this case, since the transmission line and the input impedance are mismatched, reflection occurs and the signal cannot be transmitted. For example, when the carrier frequency is 5 GHz and the relative dielectric constant is close to 1, a characteristic impedance conversion line section with a length of 15 mm is used.

[0029] The reflection characteristic 311 is a reflection characteristic of the transmission line in the wireless communication system 20 of FIG. 2(a) when the length of the transmission line portion 123 corresponding to the characteristic impedance conversion line portion in the length direction L is 15 mm and the transmission line portion 122 is supplied with power at a differential impedance of 100Ω. When the characteristic impedance is converted using a quarter-wave transformer, reflection is suppressed only in a band of 5 GHz or more, which indicates that the characteristic impedance is converted. In order to widen the conversion band of the quarter-wave transformer, a method is known in which the quarter-wave transformers are connected in multiple stages to reduce the change in impedance for each stage. For example, in the wireless communication system 20 of FIG. 2(a), when the length of the transmission line portion 123 is 60 mm, which is four stages of quarter-wave transformers for a carrier frequency of 5 GHz, the reflection characteristic is as shown in 312. That is, in the reflection characteristic 312, the reflection characteristic is reduced in a band from 1 GHz to 8 GHz, and the characteristic impedance is converted.

[0030] FIG. 3 shows that when a signal is input to a transmission line with different input impedances, reflection occurs, but when a quarter-wave transformer is used, the characteristic impedance is converted to suppress reflection, and the conversion band changes depending on the length of the transformer. In this disclosure, the length L of the transmission line section 123 corresponding to the characteristic impedance conversion line section is determined based on the minimum value of the signal frequency to be transmitted. For example, when performing communication at a data rate of 10 Gbps, it is necessary to transmit up to 500 MHz as the minimum frequency in the low range by encoding. Therefore, the length of the transmission line section 123 corresponding to the characteristic impedance conversion line section is set to 150 mm, which is a quarter of the wavelength of 500 MHz.

[0031] In the present disclosure, it is preferable that the length in the length direction L of the transmission line portion 123 (including the transmission line portion 125 in FIG. 1) corresponding to the characteristic impedance conversion line portion (third transmission line portion) is longer than a quarter of the wavelength of the carrier frequency of the data signal to be transmitted. Also, in the present disclosure, it is preferable that the length in the length direction L of the transmission line portion 123 (including the transmission line portion 125 in FIG. 1) corresponding to the characteristic impedance conversion line portion is longer than a quarter of the wavelength of the lowest frequency in the transmission band of the data signal to be transmitted.

[0032] Fig. 4 is a diagram showing the change in reflection characteristics depending on the presence or absence of a characteristic impedance conversion line portion, and the change in transfer characteristics to the receiving electrode 210 depending on the presence or absence of a characteristic impedance conversion line portion. Specifically, Fig. 4(a) is a diagram showing the change in reflection characteristics depending on the presence or absence of a characteristic impedance conversion line portion, and Fig. 4(b) shows the change in transfer characteristics to the receiving electrode 210 depending on the presence or absence of a characteristic impedance conversion line portion.

[0033] Reflection characteristic 411 in FIG. 4(a) shows the reflection characteristic when the wireless communication system 20 according to the present embodiment shown in FIG. 2(a) is applied. Specifically, the reflection characteristic 411 in FIG. 4(a) shows the reflection characteristic when the length of the transmission line portion 123 corresponding to the characteristic impedance conversion line portion in the length direction L is 150 mm, and power is fed to the transmission line portion 122 with a differential impedance of 100Ω. Also, reflection characteristic 412 in FIG. 4(a) shows the reflection characteristic when the characteristic impedance conversion line portion described above is not used, and power is fed directly to a line with a characteristic impedance of 160Ω with a differential impedance of 100Ω. From FIG. 4(a), it is shown that reflection is suppressed in a band of 500 MHz or more by using the characteristic impedance conversion line portion applied in this embodiment, and the characteristic impedance can be converted. Also, in FIG. 4(a), reflection increases sharply around 6 GHz, but this is due to the effect of resonance between the receiving electrode 210 and the transmission line 120, and can be eliminated by shortening the length of the receiving electrode 210.

[0034] A transfer characteristic 421 in FIG. 4(b) shows a transfer characteristic when the wireless communication system 20 according to the present embodiment shown in FIG. 2(a) is applied. Specifically, the transfer characteristic 421 in FIG. 4(b) shows a transfer characteristic to the receiving electrode 210 when the length of the transmission line portion 123 corresponding to the characteristic impedance conversion line portion is 150 mm in the length direction L and the transmission line portion 122 is fed with a differential impedance of 100Ω. Moreover, a transfer characteristic 422 in FIG. 4(b) shows a transfer characteristic to the receiving electrode when the characteristic impedance conversion line portion described above is not used and power is fed with a differential impedance of 100Ω to a transmission line with a differential impedance of 160Ω. When the characteristic impedance conversion line portion applied in this embodiment is not used, as shown in the transfer characteristic 422 in FIG. 4(b), the transfer becomes smaller as the frequency decreases from 2 GHz. In contrast, when the characteristic impedance conversion line portion applied in this embodiment is used, as shown in the transfer characteristic 421 in FIG. 4(b), it is possible to maintain the transfer characteristic between 200 MHz and 5 GHz. In addition, in FIG. 4(b), the transmission increases suddenly above 6 GHz. This is due to the effect of resonance between the receiving electrode 210 and the transmission line 120, and can be eliminated by shortening the length of the receiving electrode 210.

[0035] FIG. 5 shows the first embodiment of the present disclosure, and is a diagram illustrating the influence of the transfer characteristic on the receiving electrode 210 according to the position of the receiving electrode 210. Transfer characteristic 511 is the transfer characteristic to the receiving electrode 210 when the receiving electrode 210 is located above the transmission line portion 121 in the region 120a. Transfer characteristic 512 is the transfer characteristic to the receiving electrode 210 when the receiving electrode 210 is located above the transmission line portion 123 in the region 120c. Transfer characteristic 513 is the transfer characteristic to the receiving electrode 210 when the receiving electrode 210 is located above the transmission line portion 122 in the region 120b. This FIG. 5 shows that the transfer characteristic can be maintained between 200 MHz and 5 GHz regardless of the position of the receiving electrode 210 on the transmission line 120. From this result, it was found that the signal strength can be maintained even on the transmission line portion 123, which corresponds to the characteristic impedance conversion line portion of the present disclosure.

[0036] From the above results, even when the line width in the width direction W of the transmission line 120 becomes narrower (smaller) and the characteristic impedance of the transmission line 120 becomes larger, the following was found by using the characteristic impedance conversion line section of the present disclosure. That is, even in this case, it was found that the use of the characteristic impedance conversion line section of the present disclosure makes it possible to feed power without reflection and transmit it to the receiving device 200. This makes it possible to arrange the transmission line 120 in multiple lanes, enabling large-capacity communication.

[0037] In this embodiment, the conversion in the case where the line width of the transmission line 120 becomes narrower (smaller) and the characteristic impedance of the transmission line 120 becomes larger has been described, but the present invention is not limited to this. Conversely, the conversion in the case where the line width of the transmission line 120 becomes wider (larger) and the characteristic impedance of the transmission line 120 becomes smaller can also be applied in the same manner as in this embodiment. In that case, it is possible to increase the electromagnetic field coupling between the receiving device 200 and the transmitting device 100 (or the transmitting device 101), and it is possible to reduce the influence of external noise and positional fluctuations of the receiving device 200.

[0038] In the example shown in Fig. 1, a configuration is shown in which the transmission line portion 123 is provided on the side of the input signal source 110, which is a transmitter, and the transmission line portion 125 is provided on the side of the terminator 130, as the characteristic impedance conversion line portion of this embodiment. The present disclosure is not limited to this configuration, and a configuration in which a characteristic impedance conversion line portion is provided in one of the transmission line portion 123 and the transmission line portion 125 is also applicable. In addition, in the example shown in Fig. 2(a), a configuration in which a differential transmission line is applied as the transmission line 120 is shown, but the present disclosure is not limited to a differential transmission line.

[0039] In addition, in the present disclosure, the characteristic impedance and differential impedance described in the present embodiment can tolerate an error of about 5%. For example, in the present embodiment, at least one of the input signal source 110 and the terminator 130, which are the transmitters, has a differential impedance of 100Ω, but if an error of about 5% as described above is allowed, the differential impedance will be in the range of 100Ω±5Ω.

[0040] According to the first embodiment of the present disclosure, even if the line width of the transmission line 120 used for wireless communication is designed to match the mounting space, impedance matching can be achieved between the input signal source 110, which is the transmitter, and the terminator 130, thereby achieving improved communication quality.

[0041] Second Embodiment Next, a second embodiment of the present disclosure will be described. In the following description of the second embodiment, matters common to the first embodiment will be omitted, and matters different from the first embodiment will be described.

[0042] Conventionally, in order to feed signals of the same phase to two differential transmission lines, it was necessary to take measures such as dividing the lines of the power supply section, which made the structure complicated. This caused a problem of increasing the manufacturing cost. Therefore, in the second embodiment, a characteristic impedance conversion line section is used for the transmission line 120, making it possible to feed signals of the same phase to the two differential transmission lines.

[0043] Fig. 6 is a diagram showing an example of a schematic configuration of a wireless communication system 60 according to a second embodiment of the present disclosure. In Fig. 6, the same reference numerals are used for configurations with the same functions as those shown in Fig. 1 and Fig. 2, and detailed descriptions thereof will be omitted.

[0044] The wireless communication system 60 shown in Fig. 6 has two transmitting devices 101-1 and 101-2 having the same configuration as the transmitting device 101 shown in Fig. 2(a) in the first embodiment described above, and the receiving device 200 shown in Fig. 1 and Fig. 2(a) in the first embodiment described above. Here, the wireless communication system 60 shown in Fig. 6 has the same input signal source 110 as in Fig. 1.

[0045] In the first embodiment, it has been shown that it is possible to eliminate mismatching of characteristic impedance and improve communication quality by using the characteristic impedance conversion line section of the present disclosure for the transmission line 120 having a characteristic impedance different from that of the input signal source 110. In the second embodiment, as shown in Fig. 6, for two transmission lines 120-1 and 120-2 having characteristic impedances different from that of one input signal source 110, transmission line sections 123-1 and 123-2 corresponding to the characteristic impedance conversion line section of the present disclosure are used.

[0046] In the wireless communication system 60 shown in FIG. 6, the input impedance of the input signal source 110 is set to a differential impedance of 50Ω. The transmitting device 101-1 has a transmission line 120-1 including a transmission line portion 121-1, a transmission line portion 122-1, and a transmission line portion 123-1 corresponding to the characteristic impedance conversion line portion. The transmitting device 101-2 has a transmission line 120-2 including a transmission line portion 121-2, a transmission line portion 122-2, and a transmission line portion 123-2 corresponding to the characteristic impedance conversion line portion. For example, the transmission line portion 121-1 and the transmission line portion 121-2 have a differential impedance of 160Ω. The transmission line portion 122-1 and the transmission line portion 122-2 have a differential impedance of 100Ω.

[0047] FIG. 7 is a diagram showing reflection characteristics and transfer characteristics to the receiving electrode 210 in the wireless communication system 60 according to the second embodiment of the present disclosure. Specifically, FIG. 7(a) shows the reflection characteristics when the transmission line parts 123-1 and 123-2 corresponding to the characteristic impedance conversion line parts are set to 150 mm in length in the wireless communication system 60 and power is supplied from the input signal source 110 with a differential impedance of 50Ω. FIG. 7(a) shows that the reflection characteristics are small between 500 MHz and 2 GHz, indicating that the characteristic impedance is converted. FIG. 7(b) shows the transfer characteristics to the receiving electrode 210 of the receiving device 200 when power is supplied from the input signal source 110 with a differential impedance of 50Ω to the transmitting devices 101-1 and 101-2 including the characteristic impedance conversion line parts with a length of 150 mm. FIG. 7(b) shows that the signal strength can be maintained between 200 MHz and 4 GHz. 7(b), the transfer characteristic increases sharply at 6 GHz or higher, but this is due to the effect of resonance between the receiving electrode 210 and the transmission line 120, and can be eliminated by shortening the length of the receiving electrode 210. This result shows that it is possible to connect one input signal source 110 to two transmission lines 120-1 and 120-2 whose characteristic impedances differ from that of the input signal source 110.

[0048] According to the second embodiment of the present disclosure, even in a wireless communication system 60 in which two transmission lines 120-1 and 120-2 are connected to one input signal source 110, it is possible to use a transmission line 120 having a line width designed for the purpose of avoiding interference and improving communication quality.

[0049] It should be noted that the above-described embodiments of the present disclosure are merely illustrative examples of the implementation of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these. In other words, the present disclosure can be implemented in various forms without departing from its technical concept or main features.

[0050] Embodiments of the present disclosure include the following configurations. [Configuration 1] a transmission line for communicating with a communication electrode of another communication device by electromagnetic coupling; A transmitter connected to one end of the transmission line; a terminator connected to an end of the transmission line different from the one end; having The transmission line is a first transmission line portion having a first characteristic impedance; a second transmission line section that is disposed between at least one of the first transmission line section and the transmitter and the first transmission line section and the terminator, the second transmission line section having a second characteristic impedance different from the first characteristic impedance; a third characteristic impedance between the first characteristic impedance and the second characteristic impedance, the third characteristic impedance being disposed between the first transmission line portion and the second transmission line portion in a predetermined direction from the first transmission line portion to the second transmission line portion; a third transmission line portion having a structure in which the line width changes stepwise; A communication device comprising: [Configuration 2] The third transmission line section has a structure in which the line width changes at an incline in the predetermined direction. 2. The communication device according to configuration 1. [Configuration 3] The third characteristic impedance is greater than the second characteristic impedance and less than the first characteristic impedance. 3. The communication device according to configuration 1 or 2. [Configuration 4] the first transmission line portion has a first line width; the second transmission line portion has a second line width greater than the first line width, The third transmission line section has a line width that is between the first line width and the second line width and that changes stepwise in the predetermined direction. 4. The communication device according to claim 1, wherein: [Configuration 5] The third transmission line section has a length in the predetermined direction that is longer than a length corresponding to a quarter of a wavelength of a carrier frequency of a data signal to be transmitted. 5. The communication device according to claim 1, wherein: [Configuration 6] The third transmission line section has a length in the predetermined direction that is longer than a length corresponding to a quarter of a wavelength of a lowest frequency in a transmission band of a data signal to be transmitted. 5. The communication device according to claim 1, wherein: [Configuration 7] The transmission line has a line width greater than a width of the communication electrode. 7. The communication device according to any one of configurations 1 to 6. [Configuration 8] The transmission line is a differential transmission line. 8. The communication device according to any one of configurations 1 to 7. [Configuration 9] At least one of the transmitter and the terminator has a differential impedance of 100Ω±5Ω. 9. The communication device according to configuration 8. [Configuration 10] A communication device according to any one of configurations 1 to 9, the other communication device; A mobile control device that moves the communication device according to any one of configurations 1 to 9 and the other communication device relatively in the predetermined direction; A communication system comprising: [Explanation of symbols]

[0051] 10, 20, 60: wireless communication system, 100, 101: transmitting device, 110: input signal source, 120: transmission line, 120a to 120b: transmission line region, 121 to 125: transmission line section, 130: terminator, 140: reference potential surface, 141: conductor, 150: substrate, 200: receiving device, 210: receiving electrode, 220: receiving circuit, 300: movement control device, L: length direction, W: width direction

Claims

1. A transmission line extending in a predetermined direction, which communicates with communication electrodes of other communication devices via electromagnetic field coupling, A transmitter connected to one end of the aforementioned transmission line, A termination device connected to the other end of the transmission line, which is different from the one end, It has, The aforementioned transmission line is A first transmission line section having a first characteristic impedance, A second transmission line section is disposed between the first transmission line section and the transmitter, and between the first transmission line section and the terminator, and has a second characteristic impedance different from the first characteristic impedance. A third transmission line section is disposed between the first transmission line section and the second transmission line section in the predetermined direction, and has a third characteristic impedance between the first characteristic impedance and the second characteristic impedance, A communication device characterized by including

2. The communication device according to claim 1, characterized in that the third transmission line section has a structure in which the line width changes along the predetermined direction.

3. The communication device according to claim 1, characterized in that the third characteristic impedance is greater than the second characteristic impedance and less than the first characteristic impedance.

4. The first transmission line section has a first line width, The second transmission line section has a second line width that is larger than the first line width. The third transmission line section has a line width between the first line width and the second line width, and the line width changes in steps along the predetermined direction. The communication device according to feature 1.

5. The third transmission line section is such that the length in the predetermined direction is longer than the length corresponding to one-quarter of the wavelength of the carrier frequency of the data signal to be transmitted. The communication device according to feature 1.

6. The third transmission line section is such that the length in the predetermined direction is longer than the length corresponding to one-quarter of the wavelength of the lowest frequency in the transmission bandwidth of the data signal to be transmitted. The communication device according to feature 1.

7. The transmission line has a line width wider than the width of the communication electrode. The communication device according to feature 1.

8. The aforementioned transmission line is a differential transmission line. The communication device according to feature 1.

9. At least one of the transmitter and the terminator has a differential impedance of 100Ω ± 5Ω. The communication device according to feature 8.

10. A transmission line extending in a predetermined direction that communicates by electromagnetic field coupling with a communication electrode of another communication device, A transmitter connected to one end of the aforementioned transmission line, A termination device connected to the other end of the transmission line, which is different from the one end, It has, The aforementioned transmission line is A first transmission line section having a first line width, A second transmission line section is disposed between the first transmission line section and the transmitter, and between the first transmission line section and the terminator, and has a second line width different from the first line width. It includes a third transmission line section having a third line width, which is arranged between the first transmission line section and the second transmission line section in the predetermined direction, A communication device characterized in that the third line width is greater than the first line width and less than the second line width.

11. A communication device according to any one of claims 1 to 10, The aforementioned other communication device, A movement control device for moving the communication device described in any one of claims 1 to 10 and the other communication device relative to each other in the predetermined direction, A communication system characterized by having the following features.

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