Wireless transmission system, control method, and program

Abstract

To prevent a reduction in SN ratio due to mixing of noise when wireless communication is performed between a first transmission line coupler and a second transmission line coupler shorter than the opposing first transmission line coupler.SOLUTION: A wireless transmission system has: a first transmission line coupler 101 that is a pair of signal lines for transmitting differential signals, in which a receiving unit is connected to one end of each of the signal lines and a terminating resistance is connected to the other end; a second transmission line coupler 111 that is shorter than the first transmission line coupler, and opposes to the first transmission line coupler in a non-contact state to communicate electric signals with the first transmission line coupler by using electric field and / or magnetic field coupling. The wireless transmission system includes a ground 106 that, when noise is mixed in the first transmission line coupler, covers at least part of a portion of the first transmission line coupler not opposing to the second transmission line coupler.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wireless transmission system including a movable transmission line. [Background technology]

[0002] In recent years, technology has been developed to control devices having rotating movable parts, such as robot hands and network cameras, by communication. When devices having rotating movable parts are controlled by wired communication, problems such as the cable getting tangled in the shaft when the rotating movable part is rotated may occur. In order to solve this problem, a configuration may be used in which wireless data communication can be performed via the rotating movable part. Patent Document 1 discloses a configuration in which an electric signal is input from one end of a ring-shaped first transmission path, the other end of which is terminated, and a signal is detected from an opposing second transmission path.

[0003] In systems that perform wireless data communication, completely wireless operation is possible by transmitting not only data but also power wirelessly through rotating movable parts. Generally, communication is performed in a band of several tens of megahertz or more, while wireless power transmission is often performed at 10 megahertz or less. Therefore, the frequencies of wireless power transmission and data transmission do not overlap, and the two can be separated by a filter. However, the power of wireless power transmission is more than 100 times that of communication, so even if a filter is used, the wireless power transmission is likely to affect data communication.

[0004] FIG. 7(a) is a diagram showing the configuration of a coupler that performs communication through a transmission line using a differential microstrip line. The first transmission line coupler 101 is arranged over almost the entire circumference, and one end of the first transmission line coupler 101 is arranged so as to be close to the other end. A signal source 103 is connected to one end of the first transmission line coupler 101 via a differential buffer 104, and a termination resistor 102 is connected to the other end. The second transmission line coupler 111 is arranged so as to face the first transmission line coupler 101. A comparator 113 and a receiving unit 114 are connected to one end of the second transmission line coupler 111. In addition, a termination resistor 112 is connected to the other end of the second transmission line coupler 111. A signal input to the first transmission line coupler 101 is transmitted to the second transmission line coupler 111 by electric field and / or magnetic field coupling, thereby performing wireless communication.

[0005] In communications using such transmission line couplers, the input / output relationship of signals of transmission line couplers 101 and 111 can be interchanged as shown in FIG. 7(b).

[0006] Here, the second transmission line coupler 111 is sandwiched between a metal (hereinafter referred to as second ground) 115 which serves as a reference voltage for the second transmission line coupler, and a metal (hereinafter referred to as first ground) 105 which serves as a reference voltage for the first transmission line coupler 101. On the other hand, the first transmission line coupler 101 is sandwiched between the first ground 105 and the second ground 115 in a portion which faces the second transmission line coupler 111. However, in a portion of the first transmission line coupler 101 which does not face the second transmission line coupler 111, only the first ground 105 is adjacent, and the opposite side is free space. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 4-45505 Summary of the Invention [Problem to be solved by the invention]

[0008] In the portion of the first transmission line coupler that is not opposed to the second transmission line coupler, external noise such as power transmission may be mixed in through free space, which may reduce the signal-to-noise ratio (SNR) of data communication.

[0009] In view of the above, an object of the present invention is to suppress a decrease in the signal-to-noise ratio due to the introduction of noise when wireless communication is performed between a first transmission line coupler and a second transmission line coupler that is shorter than the opposing first transmission line coupler. [Means for solving the problem]

[0010] In order to achieve the above object, the wireless transmission system of the present invention has a transmitter or a receiver connected to one end and a termination resistor connected to the other end. ,ring A first transmission line coupler is arranged in a shape similar to that of a receiving Department The other end is connected to a termination resistor. ,before Shorter than the first transmission line coupler A second transmission line coupler , a metal film, and the second transmission line coupler comprises: Facing the first transmission line coupler without contact death, The second transmission line coupler communicates electrical signals using electric and / or magnetic field coupling. the second transmission line coupler is present on a surface facing the first transmission line coupler, At least part of the part that is not is caused by the metal film. cover To be It is characterized by: Effect of the Invention

[0011] According to the present invention, when wireless communication is performed between a first transmission line coupler and a second transmission line coupler that is shorter than the opposing first transmission line coupler, it is possible to suppress a decrease in the signal-to-noise ratio due to noise interference. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a system configuration of a wireless transmission system according to a first embodiment. [Diagram 2] FIG. 2 is a timing chart of the wireless transmission system according to the first embodiment. [Diagram 3] FIG. 2 is a diagram illustrating a system configuration in which a coil for wireless power transmission is included in the wireless transmission system according to the first embodiment. [Figure 4] 4 is a graph showing interference intensity of wireless power at a coupled end of the wireless transmission system according to the first embodiment. [Diagram 5] FIG. 11 is a diagram illustrating a system configuration of a wireless transmission system according to a second embodiment. [Figure 6] 10 is a graph showing interference intensity of wireless power at a coupled end of the wireless transmission system according to the second embodiment. [Figure 7] FIG. 1 is a diagram showing a system configuration of a wireless transmission system according to a conventional technique. [Figure 8] FIG. 1 is a diagram showing a system configuration for explaining a principle common to each embodiment. [Figure 9] FIG. 2 is a timing chart illustrating a principle common to each embodiment. [Figure 10] FIG. 13 is a diagram showing another system configuration for explaining the principle common to each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

[0014] First, the principle common to each embodiment will be described. Fig. 8 shows a system configuration diagram for explaining the principle common to each embodiment. A transmission line coupler 101 is a transmission line coupler on the transmission side of a differential signal, which is composed of a pair of signal lines, and is hereinafter referred to as a transmission coupler. Data transmitted from a signal source 103 (transmitter) connected to the transmission coupler 101 is input to the transmission coupler 101 as a differential signal via a differential transmission buffer 104 connected to the signal source 103. The end of the transmission coupler 101 opposite to the end connected to the signal source 103 is terminated by a termination resistor 102 that is approximately equal to the characteristic impedance of the transmission line.

[0015] The transmission line coupler 111 is a transmission line coupler on the receiving side of a differential signal, which is composed of a pair of signal lines, and is hereinafter referred to as a receiving coupler. The receiving coupler 111 can move along the transmitting coupler 101. The receiving coupler 111 is coupled to the transmitting coupler 101 by at least one of the effects of an electric field and / or a magnetic field. An input signal input from a signal source 103 passes through the electric field and / or magnetic field coupling of the transmitting coupler 101 and the receiving coupler 111, and is output from one end of the receiving coupler 111 to a comparator 113. The signal output from the receiving coupler 111 is waveform-shaped by the comparator 113 and detected as a received signal. The other end of the receiving coupler 101 is terminated by a termination resistor 112 that is approximately equal to the characteristic impedance of the transmission line.

[0016] The transmitting coupler 101 and the receiving coupler 111 operate as directional couplers. In the receiving coupler 111, the end connected to the signal source 103 in the transmitting coupler 101 is called a coupled end, and the other end is called an isolated end.

[0017] Fig. 9 shows a timing chart for explaining the principle common to each embodiment. Fig. 9(A) shows the signal output from the signal source 103, i.e., the signal input to the transmission coupler. Fig. 9(B) shows the signal at the position of the transmission coupler 101 facing the reception coupler 111. Fig. 9(C) shows the signal output from the coupled end when the isolation end of the reception coupler 111 is terminated and a signal is output from the coupled end. Fig. 9(D) shows the signal output from the comparator 113.

[0018] 9, the signal output from the coupled end of receiving coupler 111 rises when the signal input to transmitting coupler 101 rises as it is transmitted to just below receiving coupler 111. This signal maintains its rising edge for a period of time approximately proportional to the coupling length between transmitting coupler 101 and receiving coupler 111, that is, the length L1 of receiving coupler 111 shown in FIG. 8, and then the signal returns to approximately 0.

[0019] When the coupled end of the receiving coupler 111 is terminated and the signal is extracted from the isolated end, the signal becomes like a differential waveform that rises at the time when the signal input to the transmitting coupler 101 rises when it is transmitted to just below the receiving coupler 111. In any of the embodiments described below, the signal may be obtained from either the coupled end or the isolated end of the receiving coupler.

[0020] Unlike Fig. 8, Fig. 10 shows a system configuration in which a long transmission line coupler is used as a transmitting coupler and a short transmission line coupler is used as a receiving coupler. The receiving coupler 111 is configured to move along the transmitting coupler 101. Since directional couplers are reversible, wireless communication as described in Fig. 8 and Fig. 9 is possible even if the roles of transmitting and receiving are switched between the transmission line couplers as in Fig. 10. Note that in Fig. 10, components having the same roles as those included in the system configuration in Fig. 8 are assigned the same numbers as in Fig. 8.

[0021] In each embodiment, the system configuration shown in FIG. 8 or FIG. 10 is applied to a rotating body. The long transmission line coupler is arranged on the circumference of the rotating body. The opposing short transmission line coupler is arranged outside, inside, directly above, or directly below the circumference of the rotating body so as to be close to the long transmission line coupler and is configured to transmit and / or receive signals. In each embodiment, a configuration in which the short transmission line coupler is arranged directly above the long transmission line coupler is described as an example. The short transmission line coupler and the long transmission line coupler perform wireless communication by electric field and / or magnetic field coupling.

[0022] When a long transmission line coupler and a short transmission line coupler communicate wirelessly by electric field and / or magnetic field coupling, the long transmission line coupler has the open space on the transmission line. Therefore, the noise source is located in the short transmission line coupler as seen from the long transmission line coupler, and a signal is transmitted from the short transmission line coupler to the long transmission line coupler.

[0023] Each of the components of the wireless communication system described in each of the following embodiments may be included in one device, but some of them may be included in different devices. For example, the transmission line coupler on the transmission side and the reception side transmission line coupler may be included in different devices. Specifically, the system may be configured such that the transmission line coupler on the transmission side is provided on the shaft of a first device having a cylindrical shaft, and the reception side transmission line coupler is provided in a member of a second device having a member that can be fitted to the shaft. In this case, the transmission line coupler on the transmission side and the reception side transmission line coupler can communicate with each other by fitting the shaft of the first device to the member of the second device.

[0024] (First embodiment) The system configuration of the wireless transmission system according to this embodiment is shown in Fig. 1. The longer transmission line coupler 101 is the signal receiving side, and is hereinafter referred to as the receiving coupler 101. The shorter transmission line coupler 111 is the signal transmitting side, and is hereinafter referred to as the transmitting coupler 111.

[0025] Receiving coupler 101 is an arc-shaped transmission line that surrounds most of the circumference. One end of the gap of receiving coupler 101 is connected to receiving section 114, which receives an input signal, via comparator 113. The other end of receiving coupler 101 is connected to termination resistor 112.

[0026] The transmitting coupler 111 is disposed opposite the receiving coupler 101, rotates on the same axis as the receiving coupler 101, and is a transmission path configured to surround a part of the circumference. A signal source 103 is connected to one end of the arc shape of the transmitting coupler 111 via a differential buffer 104. A termination resistor 102 is connected to the other end of the transmitting coupler 111. A signal output from the signal source 103 passes through the transmitting coupler 111 and travels toward the termination resistor 102, and flows into the termination resistor 102. Here, the transmitting coupler 111 is configured with a differential microstrip line. At least the part of the surface of the transmitting coupler 111 opposite to the surface facing the receiving coupler 101, which faces the transmission path of the transmitting coupler 111, is covered with a metal film 115 of ground serving as a reference voltage.

[0027] In this embodiment, at least a part of the surface extended from the transmitting coupler 111 facing the receiving coupler 101 and not facing the transmission line of the transmitting coupler 111 is covered with a metal film 116 of ground serving as a reference voltage. In this way, by covering the part of the surface facing the receiving coupler 101 where the transmitting coupler 111 is not present with the metal film 116, the upper surface of the receiving coupler 101 is prevented from being covered only by free space or dielectric material. This prevents external noise from entering the receiving coupler 101. Here, the above-mentioned transmission line coupler and the metal film serving as ground are formed as patterns on an electric board such as FR-4 (Flame Retardant Type 4).

[0028] Like transmitting coupler 111, the surface of receiving coupler 101 opposite the surface facing transmitting coupler 111, that faces the transmission line of receiving coupler 101, is covered with ground metal film 115 which serves as a reference voltage.

[0029] 2 shows a timing chart of the wireless transmission system according to this embodiment. The signal propagating through the transmitting coupler 111 and the signal detected by the receiving coupler 101 are differential signals, but for simplicity of explanation, they are shown here as the difference signal of the differential signals.

[0030] Fig. 2(A) shows the signal output from signal source 103, i.e., the signal input to transmitting coupler 111. Fig. 2(B) shows the signal on the coupled end side of receiving coupler 101 at a position facing transmitting coupler 111. Fig. 2(C) shows the signal output from the coupled end of receiving coupler 101. Fig. 2(D) shows the signal output by comparator 113. Note that a signal like a differentiated waveform of signal (A) is generated on the isolation end side of receiving coupler 101 at a position facing transmitting coupler 111.

[0031] Signal (B) is an edge signal of input signal (A), which rises when signal (A) rises, is maintained for a time approximately proportional to the length of transmission coupler 111, and then returns to the original signal level. Signal (B) falls when signal (A) falls, is maintained for a time approximately proportional to the length of transmission coupler 111, and then returns to the original signal level.

[0032] Signal (C) is the signal actually output from the coupled end of receiving coupler 101, and is delayed by the time Δt it takes for signal (B) to propagate through receiving coupler 101. This Δt is smaller if transmitting coupler 111 is closer to the coupled end of receiving coupler 101, and is larger if it is closer to the isolated end.

[0033] The comparator 113 has a hysteresis so that it becomes “1” when the output signal (C) at the coupled end of the receiving coupler 101 becomes equal to or higher than the positive threshold voltage Vth, and becomes “0” when it becomes equal to or lower than the negative threshold voltage −Vth.

[0034] Here, in the edge signal (C), noise such as reflected waves occurs due to disturbances in the characteristic impedance of the receiving coupler 101 caused by the influence of the transmitting coupler 111, mismatch between the characteristic impedance of the receiving coupler 101 and the termination resistor, etc. However, in the comparator 113, if these noise signals are within the above-mentioned threshold voltages (Vth, -Vth), changes only with the rising and falling edges of the edge signal (C). Therefore, in the signal (D), the same signal as the signal (A) is demodulated with a delay of Δt.

[0035] Fig. 3 is a diagram showing a system configuration in which the wireless transmission system according to this embodiment further includes a coil for wireless power transmission. Centering around the rotation axis of the transmission coupler 111 and the reception coupler 101 of the wireless transmission system shown in Fig. 1, the wireless transmission system of Fig. 1 is arranged inside, and the coil for wireless power transmission is arranged outside it.

[0036] The receiving coupler 101, the termination resistor 112, the comparator 113, the receiving unit 114, and the metal film 105 are the same as those in Fig. 1. The transmitting coupler 111, the termination resistor 102, the signal source 103, the differential buffer 104, the metal film 115, and the metal film 116 are also the same as those in Fig. 1.

[0037] 3, the transmission line coupler and the coil for wireless power are configured with a pattern on a board such as FR-4. The power transmission coil 311 is configured with a pattern on an electric board 313, and in this embodiment, the coil is formed by connecting the patterns on both sides of the board with vias. AC power is supplied to the power transmission coil 311 from a power input pin 312.

[0038] The power receiving coil 301 is formed of a pattern on an electric board 303, and in this embodiment, the patterns on both sides of the board are connected by vias. A power output pin 302 is connected to the power receiving coil 301. In the wireless transmission system in Fig. 3, power is transmitted from the power transmitting coil 311 to the power receiving coil 301, thereby performing wireless power transmission.

[0039] In Fig. 3, the power coil is configured as a pattern on the same substrate as the transmission line coupler for communication, but this is not limiting, and the power coil does not have to be configured as a pattern on a substrate. Furthermore, in Fig. 3, the power coil is configured as a pattern on both sides of a double-sided substrate, but a pattern on an inner layer of a multi-layer substrate may be used.

[0040] 4A to 4C show graphs of the intensity of the interference signal output from receiving coupler 101 in the wireless transmission system shown in Fig. 3. Here, the interference signal is 2 MHz AC power input from power input pin 312, the vertical axis represents the interference signal intensity, and the horizontal axis represents the relative angle between transmitting / receiving couplers 111 and 101.

[0041] Here, (A) shows the interference intensity when the metal film 106 does not exist in the wireless transmission system shown in Fig. 3. (B) is a graph showing the interference intensity when the metal film 106 exists in the wireless transmission system shown in Fig. 3. (C) is a graph showing the interference signal intensity when the metal film 106 is further connected to the metal film 105 that serves as the reference voltage of the transmitting coupler 111 in the wireless transmission system shown in Fig. 3.

[0042] As shown in Fig. 4, in the wireless transmission system of Fig. 3, when the metal film 106 is not present (graph (A)), the interference intensity is about -61 dB, but when the metal film 106 is present (graph (B)), the interference intensity is reduced to about -65.7 dB. In this way, in the wireless transmission system as shown in Fig. 3, by providing the metal film 116 in the portion where the receiving coupler 101 does not face the transmitting coupler 111, the interference signal can be reduced by 4 dB or more. Furthermore, when the metal film 116 is connected to the metal film 115 which is the reference voltage (graph (C)), the interference intensity can be further reduced by about 0.5 dB.

[0043] As described above, in this embodiment, in a wireless transmission system that transmits not only wireless signals but also wireless power, the portion of the long transmission line coupler that is not opposed to the short transmission line coupler is covered with a metal film to reduce interference signals. In this way, by preventing the intrusion of external interference signals caused by wireless power transmission, which becomes noise in wireless communication, it is possible to suppress a decrease in the signal-to-noise ratio (SN) of wireless communication.

[0044] In addition, by connecting the metal film facing the part of the long transmission line coupler that is not facing the short transmission line coupler to another metal film (ground) that serves as a reference voltage, it is possible to further reduce interference signals.

[0045] Graphs (D) to (F) in Fig. 4 show the intensity of the interference signal when a signal is input from receiving coupler 101 and output from transmitting coupler 111, the opposite of Fig. 3. Here, (D) shows the interference intensity when metal film 106 is not present. (E) is a graph showing the interference intensity when metal film 106 is present, and (F) is a graph showing the interference intensity when metal film 116 is further connected to metal film 115 which serves as the reference voltage for transmitting coupler 111.

[0046] Here, since the transmitting coupler 101 is covered almost entirely with the metal 105 which serves as the reference potential, the strength of the interference signal is low.

[0047] In this way, if there is a noise source on the side of the couplers arranged around the entire circumference, the interference signal can be suppressed, but in general, it is unknown on which side of the transmitting / receiving coupler the noise source is located, and there is a high possibility that the noise source exists on either side of the transmitting / receiving coupler. Therefore, it is necessary to reduce the interference strength on the side where the interference signal is particularly likely to enter.

[0048] Therefore, by covering the portion of the receiving coupler 101 that is not coupled with the transmitting coupler 111 with the metal film 116 as in this embodiment, it is possible to suppress the interference signal.

[0049] Second embodiment In the first embodiment, the metal film 106 is provided so as to face the portion of the receiving coupler 101 that does not face the transmitting coupler 111. In this embodiment, further, a coplanar differential line with ground, in which ground lines are provided on both outer sides of the transmission line coupler for wireless communication, is used as the transmission line coupler, thereby further reducing the influence of external noise. In this embodiment, the differences from the first embodiment will be mainly described.

[0050] FIG. 5(a) shows the system configuration of the wireless transmission system according to the present embodiment. In FIG. 5(a), the same components as those in FIG. 3 are indicated by the same reference numerals. Unlike FIG. 3, the wireless transmission system according to the present embodiment shown in FIG. 5(a) has ground lines near the inner circumference and the outer circumference of the transmitting coupler 111 and the receiving coupler 101. Furthermore, the metal film 106 also has ground lines near the inner circumference and the outer circumference, similar to the transmitting coupler 111 and the receiving coupler 101. In the wireless transmission system shown in FIG. 5(a), at least one of the receiving coupler 101 and the transmitting coupler 111 rotates around the center O of the receiving coupler 101 as the rotation axis.

[0051] Figure 5(b) shows a cross-sectional view of the wireless transmission system shown in Figure 5(a) as seen from a direction perpendicular to the rotation axis O. An example of the configuration in which the rotation axis O is on the left side of Figure 5(b) will be described. The same components as in Figure 5(a) are denoted by the same numbers in Figure 5(b).

[0052] The transmitting coupler 111 and the metal film 115, which is a ground, face each other with the electric board 313 sandwiched therebetween. The ground lines 1154 and 1155 are connected to the metal film 115 through the vias 1152 and 1153. A plurality of the vias 1152 and 1153 are present over the entire circumference of the electric board 313, from the outer periphery to the inner periphery, and are connected so that the impedance between the ground lines 1154 and 1155 and the metal film 115 is low over the entire circumference. The transmitting coupler 111 is a grounded coplanar line together with the ground lines 1152 and 1153 and the metal film 115, and the coupler line width, the line spacing, and the distance between the signal line and the ground line are determined so as to obtain a desired impedance. The desired impedance is, for example, a differential of 100Ω. The power transmission coil 311 is disposed outside the ground line 1154.

[0053] The same is true for the receiving coupler 101. The receiving coupler 101 and the metal film 105, which is the ground, face each other with the electric board 303 in between. The ground lines 1054 and 1055 are connected to the metal film 105 through the vias 1052 and 1053. A plurality of the vias 1052 and 1053 are present over the entire circumference of the electric board 303, from the outer periphery to the inner periphery, and are connected so that the impedance between the ground lines 1054 and 1055 and the metal film 105 is low over the entire circumference. The receiving coupler 101 is a coplanar line with a ground together with the ground lines 1052 and 1053 and the metal film 105, and the coupler line width, the line spacing, and the distance between the signal line and the ground line are determined to obtain the desired impedance. The receiving coil 301 is disposed outside the ground line 1054.

[0054] 5(a), in the wireless transmission system shown in this embodiment, a ground line is also arranged on the metal film 116 facing the portion of the receiving coupler 101 that does not face the transmitting coupler 111, in the same manner as the transmitting coupler 111 and the receiving coupler 101. This makes it possible to further reduce external noise flowing into the receiving coupler 101.

[0055] 6A to 6C show graphs of the intensity of an interference signal output from receiving coupler 101 in the wireless transmission system shown in Fig. 5A. Here, the interference signal is 2 MHz AC power input from power input pin 312, the vertical axis represents the interference signal intensity, and the horizontal axis represents the relative angle between transmitting / receiving couplers 111 and 101.

[0056] In Fig. 6, (A) is a graph showing the interference intensity in the wireless transmission system shown in Fig. 5(a) when the metal film 116 is not present. (B) is a graph showing the interference intensity in the wireless transmission system shown in Fig. 5(a) when the metal film 116 is present. Furthermore, (C) is a graph showing the interference intensity in the wireless transmission system shown in Fig. 5(a) when the metal film 16 is connected to the metal film 115 that serves as the reference voltage of the transmitting coupler 111.

[0057] As shown in Fig. 6, in the wireless transmission system of Fig. 3, when the metal film 116 does not exist (graph (A)), the interference intensity is about -67.7 dB, but when the metal film 116 exists (graph (B)), the interference intensity is about -80 to 81 dB. In this way, in the wireless transmission system as shown in Fig. 6(a), by providing the metal film 116 in the portion where the receiving coupler 101 does not face the transmitting coupler 111, the interference signal can be reduced by about 14 dB. Here, when the metal film 116 is connected to the metal film 115 which is the reference voltage (graph (C)), the interference intensity is also about -80 to 81 dB, and the level of the interference signal is about the same as (B).

[0058] Moreover, when compared with the results of FIG. 4 of the first embodiment, in graph (B) under the same conditions, the interference intensity is about -66 dB in FIG. 4, but is -81 dB in FIG. 6, which shows that the configuration of this embodiment is able to reduce interference signals more effectively.

[0059] Graphs (D) to (F) in Fig. 6 show the strength of the interference signal when a signal is input from receiving coupler 101 and output from transmitting coupler 111, the opposite of Fig. 5(a). Here, (D) shows the interference strength when metal film 106 is not present. (E) is a graph showing the interference strength when metal film 106 is present, and (F) is a graph showing the interference strength when metal film 116 is further connected to metal film 115 which serves as the reference voltage for transmitting coupler 111.

[0060] Here, since the transmitting coupler 101 is covered almost entirely with the metal 105 which serves as the reference potential, the strength of the interference signal is low.

[0061] In this way, if there is a noise source on the side of the couplers arranged around the entire circumference, the interference signal can be suppressed, but in general, it is unknown on which side of the transmitting / receiving coupler the noise source is located, and there is a high possibility that the noise source exists on either side of the transmitting / receiving coupler. Therefore, it is necessary to reduce the interference strength on the side where the interference signal is particularly likely to enter.

[0062] Therefore, by covering the portion of the receiving coupler 101 that is not coupled with the transmitting coupler 111 with the metal film 116 as in this embodiment, it is possible to suppress the interference signal.

[0063] As described above, in this embodiment, in a wireless transmission system that transmits not only wireless signals but also wireless power, the interference signal can be reduced by covering with a metal film the portion of the long transmission line coupler that is not opposed to the short transmission line coupler. Here, by making the transmission line coupler a grounded coplanar line, the interference signal can be further reduced. In particular, by preventing the intrusion of external interference signals caused by wireless power transmission, which become noise in wireless communication, the decrease in the signal-to-noise ratio (SN) of wireless communication can be suppressed.

[0064] In addition, in this embodiment, the noise source has been described as an interference signal of the power signal of the wireless power transmission arranged outside the transmission line coupler, but the positional relationship between the coil of the wireless power transmission and the transmission line coupler is not limited to this positional relationship.

[0065] Furthermore, the noise source is not limited to the power signal of wireless power transmission, but may be radiation noise from a motor or electromagnetic brake, other wireless communication, etc. Other noise sources are also possible, and the present invention is not limited to noise that interferes with wireless communication.

[0066] In each of the embodiments, the coupler used for communication is a differential transmission line, but the present invention is not limited to this and may be configured as a single microstrip line or a coplanar line with a ground.

[0067] The present invention can also be realized by supplying a program for implementing one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC, etc.) that implements one or more of the functions. The program may also be provided by recording it on a computer-readable storage medium. [Explanation of symbols]

[0068] 101 Receiving coupler 102 Termination resistor 103 Signal source 104 Differential Buffer 105 Ground that serves as the reference voltage for the receiving coupler 101 111 Transmitting Coupler 112 Termination resistor 113 Comparator 114 Receiving unit 115 Ground that serves as the reference voltage for the transmitting coupler 111 116 Metal Film

Claims

1. 1. A wireless transmission system, comprising: a first transmission line coupler, one end of which is connected to a transmitter or a receiver and the other end of which is connected to a termination resistor, the first transmission line coupler being arranged in a ring shape; a second transmission line coupler, one end of which is connected to a receiving unit or a transmitting unit and the other end of which is connected to a termination resistor, the second transmission line coupler being shorter than the first transmission line coupler; A metal film, the second transmission line coupler faces the first transmission line coupler in a non-contact manner and communicates electric signals using electric field and / or magnetic field coupling; a surface of the second transmission line coupler facing the first transmission line coupler, wherein at least a part of a portion where the second transmission line coupler is not present is covered with the metal film.

2. The second transmission line coupler further has a second ground, 2. The wireless transmission system according to claim 1, wherein the second ground and the metal film are connected to each other.

3. 3. The wireless transmission system according to claim 1, wherein the first transmission line coupler and the second transmission line coupler are configured with microstrip lines.

4. 3. The wireless transmission system according to claim 1, wherein the first transmission line coupler and the second transmission line coupler are configured with a grounded coplanar line.

5. 5. The wireless transmission system according to claim 1, wherein the first transmission line coupler and the second transmission line coupler are differential lines.

6. a first coil fixed to the first transmission line coupler; a second coil fixed to the second transmission line coupler; 6. The wireless transmission system according to claim 1, wherein wireless power transmission is performed between the first coil and the second coil.

7. a differential transmission buffer connected to the transmission unit and configured to output a signal transmitted from the transmission unit as a differential signal; 6. The wireless transmission system according to claim 5, wherein the differential signal output from the differential transmit buffer is input to the first or second transmission line coupler.

8. A comparator is further provided, the comparator being connected to the receiving unit and configured to shape the waveform of an input signal.

8. The wireless transmission system according to claim 1, wherein a signal received from the first or second transmission line coupler is input to the comparator.

9. a first transmission line coupler, one end of which is connected to a transmitter or a receiver and the other end of which is connected to a termination resistor, the first transmission line coupler being arranged in a ring shape; a second transmission line coupler, one end of which is connected to a receiving section or a transmitting section, and the other end of which is connected to a termination resistor, the second transmission line coupler being shorter than the first transmission line coupler; A metal film, A method for controlling a wireless transmission system, comprising: covering, with the metal film, at least a part of a portion of a surface of the second transmission line coupler facing the first transmission line coupler, where the second transmission line coupler is not present; A control method comprising a communication step of communicating an electrical signal between the first transmission line coupler and the second transmission line coupler by opposing each other in a non-contact manner.

10. A program for causing a computer to control a wireless transmission system by the control method according to claim 9.

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