Wireless communication equipment and wireless communication systems

Abstract

To provide a wireless communication device and wireless communication system using a compact coupler that enables stable communication. [Solution] The wireless communication system 1 comprises a first wireless communication device 10 having a first coupler 100, and a second wireless communication device 11 having a second coupler 110 that electromagnetically couples with the first coupler 100 and performs wireless communication with the first wireless communication device 10. The first coupler 100 has a first signal line 101 and a first ground plane 102 having a first conductor, and the second coupler 110 has a second signal line 111 and a second ground plane 112 having a second conductor. The first ground plane 102 does not have a first conductor in a portion of the region that overlaps with the first signal line 101 in a plan view.

Description

[Technical Field]

[0001] This disclosure relates to wireless communication devices and wireless communication systems. [Background technology]

[0002] In recent years, there has been growing expectation for wireless communication technology using electromagnetic field coupling to replace wiring in the moving parts of industrial equipment. The elimination of wiring offers advantages such as space savings in the communication section and maintenance-free operation by preventing deterioration due to wiring wear. A transmission line coupler, such as the one described in Patent Document 1, can be used as a communication coupler in such cases. The transmission line coupler can be used in a fixed state facing each other, or it can accommodate sliding movement where one side is configured with a long transmission line and the other side moves along it. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-224232 [Overview of the project] [Problems that the invention aims to solve]

[0004] When replacing internal wiring with communication couplers, the available space for the couplers may be limited. To miniaturize transmission line couplers, forming them on thin substrates such as flexible circuit boards strengthens the electromagnetic coupling between signal lines and the ground plane. This limits the number of signal lines that can be used, resulting in weaker electromagnetic coupling and problems such as loss of electromagnetic coupling when lateral displacement occurs. This leads to challenges in achieving stable communication.

[0005] This disclosure has been made in view of the above-mentioned issues and aims to provide a wireless communication device and wireless communication system using a compact coupler that enables stable communication. [Means for solving the problem]

[0006] The wireless communication device of this disclosure is a wireless communication device that performs wireless communication with another wireless communication device, and comprises a coupler that electromagnetically couples with the other wireless communication device. The coupler has a signal line and a ground plane having a conductor, wherein the ground plane does not have the conductor in a portion of the region that overlaps with the signal line in a plan view. [Effects of the Invention]

[0007] According to this disclosure, a wireless communication device and wireless communication system using a compact coupler capable of stable communication can be realized. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the general configuration of a wireless communication system according to the first embodiment. [Figure 2] This characteristic diagram shows the simulation results of the gain obtained by a receiver coupler when using a transmission line with holes formed in the ground plane. [Figure 3] This characteristic diagram shows the simulation results of the gain when the center positions of the signal lines of opposing transceiver couplers are directly facing each other and when they are 0.5 mm laterally offset. [Figure 4] This is a schematic diagram showing the general configuration of a wireless communication system according to the second embodiment. [Figure 5] This is a plan view of the receiver coupler as seen from a direction perpendicular to the ground plane. [Figure 6] This characteristic diagram shows the simulation results illustrating the reflection characteristics (S11) when an electrical signal is input to a signal line, depending on the degree of overlap between the signal line and the ground plane. [Figure 7] This is a plan view showing another example of holes formed in the ground surface. [Figure 8] This is a schematic diagram showing the general configuration of a wireless communication system according to the third embodiment. [Figure 9]It is a characteristic diagram showing the simulation results of the transmission efficiency of wireless power transmission when a coupler for wireless power transmission and a coupler for wireless communication are arranged close to each other. [Figure 10] In the fourth embodiment, it is a characteristic diagram showing the simulation results of the received coupler gain when a coupler with a hole formed in the ground plane is used as the communication coupler and the size of the hole is changed.

Embodiments for Carrying Out the Invention

[0009] -Basic Configuration of Wireless Communication Devices in Various Embodiments- Specifically, when disclosing various embodiments, the basic configuration of the wireless communication devices in various embodiments will be described.

[0010] The wireless communication device of the present disclosure includes a coupler that performs wireless communication by electromagnetic field coupling with another wireless communication device. The coupler has a signal line and a ground plane having a conductor, and the ground plane is configured not to have a conductor in a part of the region overlapping the signal line in a plan view. When a conductor is formed on the entire surface of the ground plane and a coupler with a thin substrate thickness is used with the aim of miniaturizing the coupler, the ground plane and the signal line are close to each other and the electromagnetic field coupling is strengthened, so the signal line has to be designed to be narrow. In the present disclosure, a conductor missing portion is formed on the ground plane, and the missing portion creates a portion without a conductor in a part of the region overlapping the signal line in a plan view. Thereby, compared with the case where a conductor is formed on the entire surface of the ground plane, the electromagnetic field coupling between the ground plane and the signal line in the coupler becomes weaker, so the signal line can be designed to be wider. By using a signal line with a wide line width, the electromagnetic field coupling with the coupler of another wireless communication device is strengthened and a large gain can be obtained, and even when the center positions in the width direction of the couplers are shifted and arranged opposite to each other, the decrease in gain can be suppressed. Thereby, a wireless communication device using a small coupler capable of stable communication is realized.

[0011] As a specific example of the ground plane, a plurality of polygonal holes as missing portions of the conductor are periodically formed along the longitudinal direction of the signal line and further intersecting the longitudinal direction of the signal line. By forming holes in the conductor of the ground plane with appropriately adjusted polygonal shapes and sizes, sufficient gain corresponding to the small coupler of the wireless communication device can be obtained. In this case, even if the plurality of holes are not formed over the entire surface of the ground plane, the conductor may be formed over the entire surface in a predetermined region of the ground plane. By appropriately adjusting and designing the region where the plurality of holes of the ground plane are formed, the strength of the ground plane is ensured.

[0012] Also, the ground plane is preferably configured such that the conductor intersects the signal line in a region overlapping the signal line in plan view. In plan view, when there are a plurality of intersection portions between the conductor and the signal line, the reflection characteristics of the signal line are improved as the connection portions (portions horizontal to the longitudinal direction of the signal line) between adjacent intersection portions are fewer. The state where there is no such connection portion, that is, the state where the conductor existing in the region overlapping the signal line in plan view is disconnected is most preferable for improving the reflection characteristics. Thus, by appropriately adjusting and designing the intersection portion between the conductor and the signal line according to the situation of the wireless communication device, excellent reflection characteristics of the signal line can be realized and a large gain can be obtained.

[0013] The wireless communication device of the present disclosure is applied to a wireless communication system. The wireless communication system includes a first wireless communication device having a first coupler, a second wireless communication device having a second coupler that electromagnetic-field couples with the first coupler, and performing wireless communication with the first wireless communication device. The first coupler has a first signal line and a first ground plane having a first conductor, and the second coupler has a second signal line and a second ground plane having a second conductor. In the wireless communication system of the present disclosure, one or both of the following (1) and (2) hold. (1) The first ground plane does not have the first conductor in a part of the region overlapping the first signal line in plan view. (2) The second ground plane does not have the second conductor in a part of the region overlapping the second signal line in plan view.

[0014] By adopting configuration (1) or (2), the electromagnetic field coupling between the couplers of the first wireless communication device and the second wireless communication device is strengthened, making it possible to obtain a large gain, and even if the couplers are positioned opposite each other with their widthwise center positions offset, the reduction in gain is suppressed. By adopting configurations (1) and (2), an even larger gain can be obtained. Thus, according to this disclosure, a wireless communication system is realized that includes a first wireless communication device and a second wireless communication device using a compact coupler capable of stable communication.

[0015] -Specific Description of Various Embodiments- Hereinafter, preferred embodiments to which the present invention can be applied will be described in detail with reference to the drawings. In the following description, components common to multiple drawings are denoted by the same reference numerals. Therefore, the common components will be described by referring to multiple drawings together, and the description of components denoted by the same reference numerals will be omitted as appropriate.

[0016] [First Embodiment] Figure 1 is a schematic diagram showing the general configuration of the wireless communication system 1 according to the first embodiment. The wireless communication system 1 includes a receiving device 10 for wireless reception and a transmitting device 11 for wireless transmission, both of which are wireless communication devices. The receiving device 10 and the transmitting device 11 are wireless communication devices that communicate with each other via electromagnetic field coupling. The receiving device 10 includes a receiving coupler 100, a receiving circuit 120, and a termination device 130. The transmitting device 20 includes a transmitting coupler 110 that is electromagnetically coupled to the receiving coupler 100, a transmitting circuit 121, and a termination device 131. The receiving coupler 100 and the transmitting coupler 110 are configured as a so-called microstrip line.

[0017] The receiving coupler 100 is formed, for example, on a flexible printed circuit board and has a signal line 101 on one main surface and a ground surface 102 on the other main surface. The ground surface 102 is the reference potential of the signal line 101. The receiving circuit 120 is electrically connected to one end of the signal line 101. The receiving circuit 120 processes the electrical signal received by the signal line 101. The terminator 130 is electrically connected to the other end of the signal line 101 that is not connected to the receiving circuit 120. The terminator 130 provides matched termination to the signal line 101.

[0018] The transmitting coupler 110 is formed, for example, on a flexible printed circuit board and has a signal line 111 on one main surface and a ground surface 112 on the other main surface. The ground surface 112 is the reference potential of the signal line 111. The transmitting circuit 121 is electrically connected to one end of the signal line 111. The transmitting circuit 121 generates a transmission signal and inputs it to the transmission line 111. The termination 131 is electrically connected to the other end of the signal line 111 that is not connected to the transmitting circuit 121. The termination 131 provides matched termination to the signal line 111.

[0019] Next, we will describe the details of the receiver coupler 100. The signal line 101 is made of a conductor made of a highly conductive metallic material such as copper (Cu) or aluminum (Al), and has a line width W1 in the width direction. The ground plane 102 has a conductor that is the reference potential of the signal line 101. For example, Cu or Al is used as this conductor. In the receiving coupler 100, a conductor gap is formed in the ground plane 102, and this gap creates a portion of the area that overlaps with the signal line 101 in a plan view that does not have a conductor. In this embodiment, a hole 102a, which is an air gap where the conductor is missing, is formed in the ground plane 102, and a portion of the hole 102a becomes a portion of the area that overlaps with the signal line 101 in a plan view that does not have a conductor, resulting in the above configuration. Specifically, the ground surface 102 has a mesh-like arrangement of conductors and a plurality of rhombus-shaped holes 102a that are periodically arranged in a substantially horizontal direction (hereinafter simply referred to as horizontal) along the longitudinal direction of the signal line 101, and in a substantially vertical direction (hereinafter simply referred to as vertical) intersecting the longitudinal direction.

[0020] The maximum size of the hole 102a in the ground plane 102 is determined by the line width W1 and the upper limit of the transmission frequency. Specifically, if the upper frequency limit is to be 40 GHz, for example, the hole 102a should be 0.5 mm. 2 The size will be less than or equal to a certain degree. If you want the upper frequency limit to be 35GHz, for example, hole 102a should be 0.5mm. 2 Approximately ~0.85mm 2 The size will be approximately 0.85 mm. If you want to set the upper frequency limit to, for example, 25 GHz, then hole 102a should be 0.85 mm. 2 Approximately ~1.45mm 2 It will be of a certain size.

[0021] Next, we will describe the details of the transmitter coupler 110. The signal line 111 is made of a conductor such as Cu or Al and has a line width W2 in the width direction. The ground surface 112 is made of a conductor such as Cu or Al that serves as the reference potential for the signal line 111 and is provided over its entire surface.

[0022] In the wireless communication system 1 according to this embodiment, wireless communication is performed by electromagnetic field coupling between a receiving coupler 100 and a transmitting coupler 110. In Figure 1, the wireless communication system 1 is illustrated as having a receiving coupler 100 and a transmitting coupler 110 of approximately the same length, but for example, the transmitting coupler 110 may be longer than the receiving coupler 100. In that case, the receiving coupler 100 may be configured to move relatively along the transmitting coupler 110 while maintaining a constant distance on the transmitting coupler 110. This movement is realized by a movement control device, such as a motor (not shown). Note that the length of the couplers may be such that the receiving coupler 100 is longer than the transmitting coupler 110. In that case, the transmitting coupler 110 may be configured to move relatively along the receiving coupler 100 while maintaining a constant distance on the receiving coupler 100, using a movement control device.

[0023] In this embodiment, the receiving coupler 100 has a hole 102a in the ground plane 102 which serves as the reference potential, which weakens the electromagnetic field coupling with the signal line 101. Therefore, the line width W1 can be made wider compared to when there is no hole in the ground plane. By using a signal line 101 with a wide line width W1 in the receiving coupler 100, a greater gain can be obtained in the electromagnetic field coupling with the transmitting coupler 110. Furthermore, the electromagnetic field coupling between the receiving coupler 100 and the transmitting coupler 110 is maximized when the centers of the signal line 101 and the signal line 111 are approximately equal in width and facing each other. Therefore, by using a signal line 101 with a wide line width W1, a large gain can be obtained even when the signal line 101 and the signal line 111 face each other with their centers offset. If a hole 102a is formed in the ground surface 102, and no hole is formed in the ground surface 112, and the distance between the signal line 101 and the ground surface 102 is approximately equal to the distance between the signal line 111 and the ground surface 112, then the track width W1 can be made wider than the track width W2.

[0024] Figure 2 is a characteristic curve showing the simulation results of the gain obtained by a receiver coupler when using a transmission line with a hole formed in the ground plane. The simulation in Figure 2 was performed assuming the implementation of a transmission line with a characteristic impedance of approximately 50Ω on a typical FR4 substrate.

[0025] If a hole is formed in the ground plane as shown in Figure 1, and the distance between the signal line and the ground plane is 0.2 mm, then setting the line width to 0.6 mm will result in a transmission line with a characteristic impedance of approximately 50 Ω. If no hole is formed in the ground plane and the distance between the signal line and the ground plane is 0.2 mm, then setting the line width to 0.35 mm will result in a transmission line with a characteristic impedance of approximately 50 Ω.

[0026] Gain 200 is the simulation result when a receiving coupler with periodically formed diamond-shaped holes in the ground surface is opposed to a transmitting coupler without holes in the ground surface, as shown in Figure 1. The line length of both the transmitting and receiving couplers is 10 mm. Gain 201 is the simulation result when two couplers with no holes in the ground surface, a distance of 0.2 mm between the transmission line and the ground surface, and a line width of 0.35 mm are opposed to each other. The line length of both the transmitting and receiving couplers is 10 mm.

[0027] As shown in Figure 2, the gain 200 is greater than the gain 201, indicating that the gain can be increased by forming a hole in the ground plane without changing the distance between the transmission line and the ground plane or the line length.

[0028] One way to increase electromagnetic field coupling between transceivers and couplers without forming holes in the ground plane is to increase the gain by lengthening the signal line. Gain 202 is the simulation result when two couplers are facing each other with no holes in the ground plane, a distance of 0.2 mm between the signal line and the ground plane, a line width of 0.35 mm, and a line length of 12 mm. Gain 202 is approximately the same as gain 200, indicating that electromagnetic field coupling of a similar degree can be obtained by lengthening the line, similar to the case where holes are formed in the ground plane. This indicates that by forming holes in the ground plane, the required line length can be shortened and the surface area of ​​the coupler can be reduced.

[0029] Another way to improve electromagnetic coupling between transceivers and couplers without creating holes in the ground plane is to increase the distance between the signal line and the ground plane, thereby increasing the line width. Gain 203 is the simulation result when two couplers are facing each other with no holes in the ground plane, a distance of 0.4 mm between the signal line and the ground plane, a line width of 0.6 mm, and a line length of 10 mm. Gain 203 is approximately the same as gain 200, indicating that electromagnetic coupling of a similar degree can be obtained by increasing the distance between the signal line and the ground plane, as if holes were created in the ground plane. This suggests that by creating holes in the ground plane, the distance between the signal line and the ground plane can be narrowed, allowing for a thinner coupler.

[0030] The above simulation results show that by forming a hole in the ground plane, the coupler can be miniaturized while obtaining a large gain. Based on these simulation results, the receiving device 10 in this embodiment can obtain a large gain with a small receiving coupler 100 by, for example, forming a hole 102a in the ground plane 102 of the receiving coupler 100, as shown in Figure 1.

[0031] Figure 3 is a characteristic diagram showing the simulation results of the gain when the center positions of the signal lines of the opposing transceiver couplers are directly facing each other and when they are laterally offset by 0.5 mm. Figure 3(a) shows the results when the simulation was performed under the same conditions as when a gain of 200 was obtained as shown in Figure 2. Figure 3(b) shows the results when the simulation was performed under the same conditions as when a gain of 201 was obtained as shown in Figure 2.

[0032] Gain 300 is the simulation result when the signal lines of the transmit / receive coupler are aligned at their center positions in the width direction. Gain 301 is the simulation result when the signal lines of the transmit / receive coupler are offset laterally by 0.5 mm at their center positions in the width direction. As shown in Figure 3(a), for example, at 20 GHz, it can be seen that gain 301 is about 3.3 dB lower than gain 300.

[0033] Gain 302 is the simulation result when the transmit / receive coupler signal lines are facing each other with their widthwise center positions aligned. Gain 303 is the simulation result when the transmit / receive coupler signal lines are facing each other with their widthwise center positions shifted laterally by 0.5 mm. As shown in Figure 3(b), for example, at 20 GHz, it can be seen that gain 303 is about 4.2 dB lower than gain 304.

[0034] The above simulation results show that by using a miniaturized coupler with a hole formed in the ground surface, it is possible to increase resistance to lateral displacement of the transmitting and receiving coupler. In the receiving device 10 of this embodiment, based on these simulation results, for example, as shown in Figure 1, a hole 102 is formed in the ground surface 102 of the receiving coupler 100, thereby suppressing performance degradation even if lateral displacement occurs between the receiving coupler 100 and the transmitting coupler 110.

[0035] As described above, in this embodiment, even when a transmitting coupler and a receiving coupler that electromagnetically couples are mounted on a small substrate, the line width can be widened by appropriately forming holes in the ground plane, thereby obtaining a large gain and becoming more resistant to lateral displacement. This enables the realization of a wireless communication device and wireless communication system using a small coupler that enables stable communication.

[0036] In this embodiment, the transmitting coupler 110 was described as having a signal line 111 and a ground plane 112, but it may also be an inductively coupled coupler such as a patch coupler. In that case, the terminator 131 may be omitted.

[0037] In this embodiment, it was explained that a hole 102a is formed in the ground plane 102 of the receiving coupler 100, and no hole is formed in the ground plane 112 of the transmitting coupler 110. Instead of this configuration, it is also possible to have a configuration in which no hole is formed in the ground plane 102, and a hole similar to hole 102a is formed in the ground plane 112, or a hole similar to hole 102a is formed in both the ground plane 102 and the ground plane 112. In this case as well, a wireless communication device and wireless communication system using a small coupler capable of stable communication can be realized, similar to the configuration in Figure 1. In particular, when holes are formed in both the ground plane 102 and the ground plane 112, the line width is increased for both signal lines 101 and 111, resulting in greater gain and greater resistance to lateral displacement.

[0038] Furthermore, although the receiving coupler 100 and the transmitting coupler 110 were described as being microstrip lines in this embodiment, they may also be coplanar lines with ground guards or differential lines.

[0039] When a coplanar line having a ground guard is used as a coupler, the coupler is formed, for example, on a flexible printed circuit board. One main surface of the board is provided with a signal line and a pair of ground guards on both sides thereof. The other main surface of the board is provided with a ground surface that serves as the reference potential. This ground surface has multiple polygonal holes formed in the conductor, similar to the ground surface in the embodiments of this disclosure. In this case as well, similar to the embodiments, by appropriately forming holes in the ground surface, the line width of the signal line can be widened, a large gain can be obtained, and resistance to lateral displacement can be increased. This enables the realization of wireless communication devices and wireless communication systems using a compact coplanar line type coupler that enables stable communication.

[0040] When a differential line is used as a coupler, the coupler is formed, for example, on a flexible printed circuit board. A pair of parallel signal lines are provided on one main surface of the board. A ground surface, which serves as the reference potential, is provided on the other main surface of the board. This ground surface has multiple polygonal holes formed in the conductor, similar to the ground surface in the embodiments of this disclosure. In this case as well, as in the embodiments, by appropriately forming holes in the ground surface, the line width of the signal lines can be widened, a large gain can be obtained, and resistance to lateral displacement can be increased. This enables the realization of wireless communication devices and wireless communication systems using a small differential line type coupler that enables stable communication.

[0041] Furthermore, transmission lines in couplers with holes in the ground plane have greater transmission loss than transmission lines in couplers without holes in the ground plane. Therefore, for example, when the transmitting coupler is longer than the receiving coupler, it is preferable to have holes in the ground plane of the receiving coupler and no holes in the ground plane of the transmitting coupler.

[0042] According to this embodiment, even if a small transceiver coupler is designed to fit the mounting space of the communication coupler, a large electromagnetic field coupling can be obtained between the transceiver coupler, thus realizing a communication device capable of stable communication.

[0043] [Second Embodiment] In the second embodiment, a wireless communication device and wireless communication system are disclosed, similar to the first embodiment, in which a plurality of periodically arranged holes are formed on the ground surface of the coupler, but it differs from the first embodiment in that the shape of the holes formed on the ground surface is different.

[0044] Figure 4 is a schematic diagram showing the general configuration of the wireless communication system 4 according to the second embodiment. In Figure 4, components with the same functions as those shown in Figure 1 of the first embodiment are denoted by the same reference numerals, and their detailed explanation is omitted.

[0045] The wireless communication system 4 includes a receiving device 40 for wireless reception and a transmitting device 41 for wireless transmission, both of which are wireless communication devices. The receiving devices 40 and 410 are wireless communication devices that communicate wirelessly with each other by electromagnetic field coupling. The receiving device 40 includes a receiving coupler 400, a receiving circuit 120, and a terminator 130. The transmitting device 40 includes a transmitting coupler 410 that is electromagnetically coupled to the receiving coupler 400, a transmitting circuit 121, and a terminator 131. The receiving coupler 400 and the transmitting coupler 410 are configured as a so-called microstrip line.

[0046] The receiving coupler 400 is formed, for example, on a flexible printed circuit board, and has a signal line 101 on one main surface and a ground surface 402 on the other main surface. The ground surface 402 is the reference potential of the signal line 101. The transmitting coupler 410 is formed, for example, on a flexible printed circuit board, and has a signal line 111 on one main surface and a ground surface 412 on the other main surface.

[0047] Next, we will describe the details of the receiver coupler 400. The signal line 101 has a line width W1 in the width direction. The ground plane 402 has a conductor that is the reference potential of the signal line 101. In the receiving coupler 400, the ground plane 402 is configured such that it does not have a conductor in a part of the region that overlaps with the signal line 101 in a plan view. In the receiving coupler 400, a portion of the ground plane 402 is formed where there is a conductor gap, and this gap creates a portion of the region that overlaps with the signal line 101 in a plan view that does not have a conductor. In this embodiment, a hole 402a, which is an air gap where there is a conductor gap, is formed in the ground plane 402, and a part of the hole 402a becomes a portion of the region that overlaps with the signal line 101 in a plan view that does not have a conductor, thus resulting in the above configuration. Specifically, the ground plane 402 has conductors arranged in a mesh pattern. The ground surface 402 has rectangular holes 402a that are periodic in a direction approximately horizontal (hereinafter simply referred to as horizontal) and approximately vertical (hereinafter simply referred to as vertical) to the longitudinal direction of the signal line 101, respectively, with sides horizontal and sides vertical to the signal line 101.

[0048] The maximum size of the hole 402a on the ground plane 402 is determined by the line width W1 and the upper limit of the transmitted frequency, similar to the size of the hole 102a on the ground plane 102 in the first embodiment. Specifically, when the upper limit frequency is, for example, 40 GHz, the hole 402a has a size of 0.5 mm or less. 2 When the upper limit frequency is, for example, 35 GHz, the hole 402a has a size of about 0.5 mm 2 to about 0.85 mm. 2 When the upper limit frequency is, for example, 25 GHz, the hole 402a has a size of about 0.85 mm 2 to about 1.45 mm. 2 That is the size range.

[0049] Next, the details of the transmission coupler 410 will be described. The signal line 111 has a line width W2 in the width direction. The ground plane 412 has a conductor that serves as the reference potential of the signal line 111. In the transmission coupler 410, the ground plane 412 is configured to have no conductor in a part of the region overlapping the signal line 111 in plan view. In the transmission coupler 410, a conductor missing portion is formed on the ground plane 412, and the missing portion creates a part having no conductor in a part of the region overlapping the signal line 111 in plan view. In this embodiment, by forming a hole 412a, which is a void where the conductor is missing, on the ground plane 412, a part of the hole 412a becomes a part having no conductor in a part of the region overlapping the signal line 111 in plan view, and thus has the above configuration. Specifically, the ground plane 412 has a plurality of square holes 412a arranged periodically in a horizontal direction along the longitudinal direction of the signal line 111 and in a vertical direction intersecting the longitudinal direction. One side of the hole 412a is substantially horizontal along the longitudinal direction of the signal line 111, and the other side is substantially vertical intersecting the longitudinal direction of the signal line 111.

[0050] The maximum size of the hole 412a on the ground plane 412 is determined by the line width W2 and the upper limit of the transmitted frequency, similar to the maximum size of the hole 102a on the ground plane 102 in the first embodiment. Specifically, when the upper limit frequency is, for example, 40 GHz, the hole 412a has a size of 0.5 mm 2The size will be less than or equal to a certain degree. If you want the upper frequency limit to be, for example, 35GHz, then hole 412a should be 0.5mm. 2 Approximately ~0.85mm 2 The size will be approximately 0.85 mm. If you want to set the upper frequency limit to, for example, 25 GHz, then hole 412a should be 0.85 mm. 2 Approximately ~1.45mm 2 It will be of a certain size.

[0051] In this embodiment, the receiving coupler 400 and the transmitting coupler 410, like the receiving coupler 100 described in the first embodiment, have holes 402a and 412a formed in the ground planes 402 and 412, which serve as the respective reference potentials. Therefore, compared to a configuration without holes in the ground plane, the line widths W1 and W2 of the signal lines 101 and 111 can be widened. This strengthens the electromagnetic field coupling between the transmitting and receiving couplers 400 and 410, allowing for a large gain even with a small coupler, and also ensuring sufficient gain even if there is a shift in the center position between the signal lines 101 and 111.

[0052] Figure 5 is a plan view of the receiver coupler 400 as seen from a direction perpendicular to the ground plane 402. The first part 500 is the portion of the mesh conductor on the ground plane 402 that extends along the signal line 101, in this case the portion that is parallel to the longitudinal direction of the signal line 101. The second part 501 is the portion of the mesh conductor on the ground plane 402 that intersects with the signal line 101, in this case the portion that is perpendicular to the longitudinal direction of the signal line 101. Figure 5(a) shows a design where the signal line 101 and the first portion 500 of the ground plane 402 do not overlap. Figure 5(b) shows a design where the signal line 101 and the first portion 500 of the ground plane 402 overlap.

[0053] As shown in Figure 5(a), the effect of weakening the electromagnetic field coupling between the signal line 101 and the ground plane 402, thereby strengthening the electromagnetic field coupling between the transmitter and receiver, and widening the line width W1, is more effectively achieved when there is a larger overlap between the signal line 101 and the second portion 501 of the ground plane 402. The same applies to the transmitter coupler 410.

[0054] Figure 6 is a characteristic diagram showing the simulation results of the reflection characteristics (S11) when an electrical signal is input to the signal line 101, depending on the degree of overlap between the signal line 101 and the ground plane 402. Figure 6(a) shows the change in S11 as the overlap width between the signal line 101 and the first section 500 at the widthwise end of the signal line 101, while keeping the track width W1 and the width of the first section 500 constant, as shown in Figure 5(b). Figure 6(a) shows that as the overlap width increases, S11 increases. Figure 6(b) shows the change in S11 when the width of line 500 changes, while the track width W1 is kept constant, and the signal line 101 and the first section 500 overlap with their centers aligned in the width direction. Figure 6(b) shows that S11 increases as the overlap width increases.

[0055] The above simulation results demonstrate the following: When a hole is formed in the ground plane and the conductor remaining in the ground plane includes both a portion horizontal to the signal line and a portion vertical to the signal line, the less the signal line and the horizontal portion overlap in a plan view (the amount of connection between the conductor and the signal line at the intersection), the better the reflection characteristics of the signal line. Based on these simulation results, the wireless communication system 4 in this embodiment is preferably configured as follows: For each of the receiving device 40 and transmitting device 41, the signal line and the ground plane are arranged such that, for example, in a plan view, only the signal line and the second portion 501 of the ground plane overlap (so that the conductor in the region overlapping with the signal line is separated), as shown in Figure 5(a). Furthermore, even if, for example, design limitations cause overlap between the signal line and the first portion 500 in a plan view, as shown in Figure 5(b), the signal line and the ground plane are arranged to minimize such overlap as much as possible.

[0056] As described above, in this embodiment, the positional relationship between the transmission line and the ground plane in a plan view is designed as described above. This allows for a wider signal line width and greater gain, even when configuring a transceiver coupler using a small substrate, and makes it more resistant to lateral displacement. This enables the realization of a wireless communication device and wireless communication system using a compact coupler that enables stable communication.

[0057] In this embodiment, an example is given of forming a rectangular hole in the ground surface with sides horizontal and vertical to the longitudinal direction of the signal line. However, the shape of the hole formed in the ground surface may be a polygon with more than four sides. Figure 7(a) shows a case in which a hexagonal hole 701a is periodically formed in the ground surface 701 of at least one of the couplers of the receiving device 40 and the transmitting device 41. In this way, when the line width of the conductor of the ground surface 701 is wide, it is considered that there is a portion of the conductor that is horizontal to the signal line 702. Therefore, it is preferable to design the ground surface to have a positional relationship with the signal line similar to that of this embodiment described above.

[0058] Furthermore, although this embodiment illustrates the case where holes are periodically formed across the entire ground surface, holes may also be formed on only a portion of the ground surface. Figure 7(b) shows a case in which, for example, four rectangular holes 703a are formed in the central part of the ground surface 703 of at least one of the couplers of the receiving device 40 and the transmitting device 41, with sides horizontal and perpendicular to the longitudinal direction of the signal line 702. Considering the improvement of the strength of the ground surface 703, conductors are formed over the entire surface in areas other than the central part of the ground surface 703. Thus, even if the holes to be formed on the ground surface are not formed over the entire ground surface, it is sufficient if the ground surface is configured so that there are no conductors in a portion of the area that overlaps with the signal line in a plan view.

[0059] According to this embodiment, even if a small transceiver coupler is designed to fit the mounting space of the communication coupler, a large electromagnetic field coupling can be obtained between the transceiver coupler, thus realizing a communication device capable of stable communication.

[0060] [Third Embodiment] In the third embodiment, similar to the first and second embodiments, a wireless communication device and wireless communication system are disclosed in which a plurality of periodically arranged holes are formed on the ground plane of a wireless communication coupler, but it differs from the first and second embodiments in that it further includes a wireless power transmission coupler.

[0061] Figure 8 is a schematic diagram showing the general configuration of the wireless communication system 8 according to the third embodiment. In Figure 8, components with the same functions as those shown in Figure 1 are denoted by the same reference numerals, and their detailed explanations are omitted.

[0062] The wireless communication system 8 includes a receiving device 80 and a transmitting device 81, both of which are wireless communication devices. The receiving device 80 is a wireless communication device that can simultaneously perform wireless communication via electromagnetic field coupling and wireless power transmission via electromagnetic induction, magnetic field resonance, or electric field coupling with the transmitting device 81. The receiving device 80 includes a receiving coupler 800, a receiving circuit 120, a terminator 130, a power receiving circuit 821, and a load 822. The transmitting device 80 includes a transmitting coupler board 810 that electromagnetically couples with the receiving coupler 800, a transmitting circuit 121, a terminator 131, a power transmission circuit 831, and a power supply 832.

[0063] The receiving coupler 800 has a signal line 101, a ground plane 102, and a winding 820 with one or more turns. The receiving coupler 800 is formed, for example, by a printed circuit board. The ground plane 102 is the reference potential of the signal line 101. The winding 820 is a coupler that receives power. The power receiving circuit 821 is composed of a known rectifier circuit. The power receiving circuit 821 converts the power received by the winding 820 and supplies it to the load 822. The load 822 is something that operates on the supplied power, such as a motor.

[0064] The transmitting coupler 810 has a signal line 111, a ground plane 112, and a winding 830 with one or more turns. The transmitting coupler 810 is formed, for example, by a printed circuit board. The ground plane 112 is the reference potential of the signal line 111. The winding 830 is a coupler that transmits power to the winding 820. The power transmission circuit 831 is composed of known switching circuits. The power transmission circuit 831 converts the voltage supplied from the power supply 832 into the frequency of the clock signal and supplies it to the winding 830.

[0065] In the wireless communication system 8 according to this embodiment, if the transmitting coupler 810 is longer than the receiving coupler 820 in the direction along the transmission line, the receiving coupler 800 may move relative to the transmitting coupler 810 while maintaining a constant distance on the transmitting coupler 810. This movement is achieved by a movement control device such as a motor. The length of the couplers may be such that the receiving coupler 800 is longer than the transmitting coupler 810. In that case, the transmitting coupler 810 may move relative to the receiving coupler 800 while maintaining a constant distance on the receiving coupler 800 using a movement control device. The lengths of the receiving coupler 800 and the transmitting coupler 810 may also be approximately the same. In that case, the system may be used without a movement control device.

[0066] Couplers used in wireless power transmission experience reduced transmission efficiency when metal is present in their vicinity. This is because, when metal is present near the transmitting coupler, the magnetic flux generated from the transmitting coupler creates eddy currents on the metal surface, which are converted into heat. To prevent this, it is preferable to place wireless power transmission couplers and wireless communication couplers as far apart as possible. However, due to space constraints and other factors, they may have to be placed close together, resulting in low transmission efficiency.

[0067] In this embodiment, the receiving coupler 800 and the transmitting coupler 810, similar to the first embodiment, have holes 102a and 112a in the ground planes 102 and 112, which are the reference potentials of the respective transmission lines, thereby widening the line widths W1 and W2. This strengthens the electromagnetic field coupling between the transmission lines, allowing for a large communication gain even with a small coupler, and also allows for a large communication gain even if the centers between the signal lines are misaligned. Furthermore, when a wireless communication coupler is placed in close proximity to a wireless power transmission coupler, the eddy currents generated on the ground plane by the transmitting coupler can be reduced. This reduces the degradation of the transmission efficiency of wireless power transmission.

[0068] Figure 9 is a characteristic diagram showing the simulation results of the transmission efficiency of wireless power transmission when the wireless power transmission coupler and the wireless communication coupler are placed in close proximity, as shown in Figure 8. The simulation in Figure 9 was performed assuming that the receiving coupler and transmitting coupler are mounted on a typical FR4 substrate.

[0069] Efficiency 900 is the simulation result when diamond-shaped holes are periodically formed on the ground plane of the transmit and receive transmission lines of the wireless communication coupler, as shown in Figure 8. Efficiency 901 is the simulation result when a wireless power transmission coupler and a wireless communication coupler using a transmission line without holes formed on the ground plane are placed in close proximity. Efficiency 902 is the simulation result when only a wireless power transmission coupler is present.

[0070] As shown in Figure 9, when no holes are formed in the ground plane, the transmission efficiency deteriorates significantly. On the other hand, by forming holes in the ground plane, the deterioration of transmission efficiency is reduced.

[0071] From the above simulation results, it was found that even when the coupler for wireless power transmission and the coupler for wireless communication are placed in close proximity, the degradation of the transmission efficiency of wireless power transmission can be reduced by using a coupler with a hole formed in the ground plane.

[0072] In this embodiment, we have illustrated the case where holes are formed on the ground surfaces of both the transmitting and receiving couplers. However, holes may be formed only on the ground surface of the transmitting coupler or only on the ground surface of the receiving coupler. Even in this case, a wireless communication device and wireless communication system using a compact coupler that can reduce the degradation of the transmission efficiency of wireless power transmission can be realized, similar to the configuration in Figure 8.

[0073] Furthermore, although this embodiment illustrates a case where the coupler for wireless power transmission and the coupler for wireless communication are formed on the same substrate, they may be formed on separate substrates.

[0074] According to this embodiment, even if the coupler for wireless power transmission and the coupler for wireless communication are placed close together to match the mounting space of the coupler, the impact on the transmission efficiency of wireless power transmission can be reduced, thereby realizing a wireless communication system that enables highly efficient wireless power transmission.

[0075] [Fourth Embodiment] In the first and second embodiments, it was shown that by forming a hole in the ground plane of the coupler, it is possible to miniaturize the coupler while ensuring high gain. In the fourth embodiment, it is shown that a coupler with a hole in the ground plane functions as a filter. The configuration of the wireless communication system according to this embodiment and the function of each component are the same as in the first embodiment, so a description is omitted.

[0076] The receiving coupler 100 in this embodiment utilizes the principle that the ground plane 102, which serves as the reference potential, has holes, which weakens the electromagnetic field coupling with the signal line 101, allowing for a wider line width W1 compared to a ground plane without holes. The electromagnetic field coupling between the signal line 101 and the ground plane 102 weakens as the size of the holes in the ground plane increases. When the electromagnetic field coupling between the signal line 101 and the ground plane 102 decreases, the transmission characteristics of the transmission line deteriorate rapidly as the frequency increases. This property can be used to use the transmitting and receiving coupler in this embodiment as a low-pass filter.

[0077] Figure 10 is a characteristic diagram showing the simulation results of the receiver coupler gain when a coupler with a hole formed in the ground plane is used as a communication coupler and the size of the hole is changed. In the simulation in Figure 10, the characteristic impedance of the transmission line is kept at 50Ω, while the size of the hole in the ground plane and the amount of conductor are changed.

[0078] Figure 10 shows that as the hole in the ground plane increases in size, the gain obtained at higher frequencies decreases. Because this change in gain deteriorates sharply, as shown in the figure, it can be used as a low-pass filter to cut high-frequency components. From these results, it was found that a coupler with a hole in the ground plane can be used as a low-pass filter when used as a receiving coupler in wireless communication. The frequency to be cut can be controlled by the size of the hole in the ground plane. This enables the realization of a convenient wireless communication system with a built-in low-pass filter in a configuration using a compact coupler capable of stable communication.

[0079] In this embodiment, it was explained that a hole 102a is formed in the ground plane 102 of the receiving coupler 100, and no hole is formed in the ground plane 112 of the transmitting coupler 110. Instead of this configuration, it is also possible to have a configuration in which no hole is formed in the ground plane 102, and a hole similar to hole 102a is formed in the ground plane 112, or a hole similar to hole 102a is formed in both the ground plane 102 and the ground plane 112. Even in this case, a convenient wireless communication system with a built-in low-pass filter can be realized in a configuration using a small coupler capable of stable communication.

[0080] The disclosure of various embodiments includes the following configurations. (Composition 1) A wireless communication device that communicates wirelessly with other wireless communication devices, The device includes a coupler that electromagnetically couples with the aforementioned other wireless communication device, The aforementioned coupler is, Signal line and, A ground plane having a conductor, It has, The ground plane, in a plan view, does not have the conductor in a portion of the region that overlaps with the signal line. Wireless communication device. (Configuration 2) The ground surface has a missing portion of the conductor, and the missing portion creates a part that does not have the conductor. The wireless communication device described in Configuration 1. (Composition 3) The ground surface has multiple polygonal holes periodically formed as the missing portions. The wireless communication device described in Configuration 2. (Composition 4) The ground surface has the plurality of holes formed along the longitudinal direction of the signal line. The wireless communication device described in Configuration 3. (Composition 5) The ground surface is formed such that the plurality of holes intersect the longitudinal direction of the signal line. A wireless communication device as described in configuration 3 or 4. (Composition 6) The ground surface has a region where the conductor is formed over its entire surface. A wireless communication device as described in any one of configurations 1 to 5. (Composition 7) The conductor intersects the signal line in the region where it overlaps with the signal line in a plan view. A wireless communication device as described in any one of configurations 1 to 6. (Composition 8) The ground plane is such that the conductor located in the region overlapping with the signal line in a plan view is divided. A wireless communication device as described in any one of configurations 1 to 7. (Composition 9) The maximum size of the portion without the conductor is determined by the upper limit frequency of the signal transmitted to the signal line. A wireless communication device as described in any one of configurations 1 to 8. (Composition 10) The aforementioned coupler functions as a low-pass filter. The wireless communication device described in Configuration 1. (Composition 11) The coupler is a microstrip line or a coplanar line with a ground guard. A wireless communication device as described in any one of configurations 1 to 10. (Composition 12) It is a receiving device that performs wireless reception. A wireless communication device as described in any one of configurations 1 to 11. (Composition 13) It is a transmitting device that performs wireless transmission. A wireless communication device as described in any one of configurations 1 to 11. (Composition 14) A first wireless communication device having a first coupler, A second wireless communication device having a second coupler that electromagnetically couples with the first coupler, and performing wireless communication with the first wireless communication device, Equipped with, The first coupler is, First signal line and, A first ground plane having a first conductor, It has, The second coupler is, The second signal line and, A second ground plane having a second conductor, It has, One or both of the following conditions (1) and (2) are true: (1) The first ground plane does not have the first conductor in a portion of the region that overlaps with the first signal line in a plan view. (2) The second ground plane does not have the second conductor in a portion of the region that overlaps with the second signal line in a plan view. Wireless communication system. [Explanation of Symbols]

[0081] 1,4,8 Wireless Communication Systems 10,40,80 Receiver 11,41,81 Transmitter 100,400,800 Receiver Coupler 101,111 signal lines 102,112,402,412 Ground surface 102a, 402a, 412a, 701a, 703a Hole 110,410,810 Transmitter Coupler 120 Receiving Circuit 121 Transmitter Circuit 130,131 Terminator 200~203, 300~303 Receiving Gain 500 Part 1 501 Part 2 820,830 Wireless Power Transmission Coupler 821 Power receiving circuit 822 load 831 Power transmission circuit 832 Power supply 900~902 Wireless power transmission efficiency

Claims

1. A wireless communication device that communicates wirelessly with other wireless communication devices, The device includes a coupler that electromagnetically couples with the aforementioned other wireless communication device, The aforementioned coupler is, Signal line and, A ground plane having a conductor, It has, The ground plane, in a plan view, does not have the conductor in a portion of the region that overlaps with the signal line. Wireless communication device.

2. The ground surface has a missing portion of the conductor, and the missing portion creates a part that does not have the conductor. The wireless communication device according to claim 1.

3. The ground surface has multiple polygonal holes periodically formed as the missing portions. The wireless communication device according to claim 2.

4. The ground surface has the plurality of holes formed along the longitudinal direction of the signal line. The wireless communication device according to claim 3.

5. The ground surface is formed such that the plurality of holes intersect the longitudinal direction of the signal line. The wireless communication device according to claim 3.

6. The ground surface has a region where the conductor is formed over its entire surface. The wireless communication device according to claim 1.

7. The conductor intersects the signal line in the region where it overlaps with the signal line in a plan view. The wireless communication device according to claim 1.

8. The ground plane is such that the conductor located in the region overlapping with the signal line in a plan view is divided. The wireless communication device according to claim 1.

9. The maximum size of the portion without the conductor is determined by the upper limit frequency of the signal transmitted to the signal line. The wireless communication device according to claim 1.

10. The aforementioned coupler functions as a low-pass filter. The wireless communication device according to claim 1.

11. The coupler is a microstrip line or a coplanar line with a ground guard. The wireless communication device according to claim 1.

12. It is a receiving device that performs wireless reception. The wireless communication device according to claim 1.

13. It is a transmitting device that performs wireless transmission. The wireless communication device according to claim 1.

14. A first wireless communication device having a first coupler, A second wireless communication device having a second coupler that electromagnetically couples with the first coupler, and performing wireless communication with the first wireless communication device, Equipped with, The first coupler is, First signal line and, A first ground plane having a first conductor, It has, The second coupler is, The second signal line and, A second ground plane having a second conductor, It has, One or both of the following conditions (1) and (2) are true: (1) The first ground plane does not have the first conductor in a portion of the region that overlaps with the first signal line in a plan view. (2) The second ground plane does not have the second conductor in a portion of the region that overlaps with the second signal line in a plan view. Wireless communication system.

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