Wireless communication device

Abstract

To achieve both acceleration of data transmission and a reduction in height of a radio communication device.SOLUTION: A radio communication device has a first antenna for performing radio communication by electromagnetic field coupling, and communication control means for transmitting or receiving signals in the first antenna. The first antenna includes a first conductor that has a shape along an arc shape centered on a predetermined axis, and a second conductor that is arranged on the inside of the first conductor with respect to the predetermined axis in a viewpoint in a reference direction parallel to the predetermined axis, and has a shape along an arc shape centered on the predetermined axis. A second signal fed to one end of the second conductor is fed with a predetermined amount of delay from a first signal fed to one end of the first conductor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to wireless communication technology.

Background Art

[0002] In recent years, systems for performing communication via rotatable moving parts such as robotic arms and network cameras have been developed. Patent Document 1 discloses a technique for performing data transmission using an electromagnetic field between a differential transmission line and a probe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, the amount of data transmitted by wireless communication has been increasing, and higher speed data transmission in wireless communication devices has been demanded. Furthermore, along with the reduction in the height (thinning) of devices, a reduction in the height of the wireless communication devices themselves included in the devices is also desired. When providing a differential transmission line on a plane such as a dielectric substrate for the purpose of reducing the height of the wireless communication device of Patent Document 1, there is a problem that a difference occurs in the wiring length between the differential pairs of the differential transmission line, and the high speed is limited.

[0005] An object of the present invention is to achieve both high-speed data transmission and reduction in the height of a wireless communication device.

Means for Solving the Problems

[0006] In order to solve the above problems, a wireless communication device according to the present invention Antennas of other communications devices a first antenna for performing electromagnetic field coupling Using wireless communication, and communication control means for transmitting signals of the first antenna via has, and the first antenna is centered on a predetermined axis Let's assume A first conductor having a shape along an arc, and a reference direction parallel to the predetermined axis, positioned inward from the first conductor with respect to the predetermined axis, and centered on the predetermined axis. Let's assume It includes a second conductor that has a curved shape. , by the communication control means, At one end of the first conductor First signal is input The second signal is then transmitted to one end of the second conductor. input The second signal is, For the first signal Having a predetermined delay amount The predetermined delay amount is a value between 0.1 × ΔT and 0.9 × ΔT, where ΔT is the propagation delay difference resulting from the difference between the propagation delay from one end of the first conductor to the other end and the propagation delay from one end of the second conductor to the other end. It is characterized by the following: [Effects of the Invention]

[0007] According to the present invention, it is possible to achieve both high-speed data transmission and a low-profile wireless communication device. [Brief explanation of the drawing]

[0008] [Figure 1] Block diagram showing an example configuration of the wireless communication system in the first embodiment. [Figure 2] Diagram illustrating the challenges of conventional technology [Figure 3] A diagram illustrating the effects of inserting a delay path. [Figure 4] A diagram showing an example of the structure of a differential transmission line and coupler. [Figure 5] A diagram showing an example of simulation results. [Figure 6] Block diagram showing an example configuration of the wireless communication system in the second embodiment. [Figure 7] Block diagram showing an example configuration of a wireless communication system in the third embodiment. [Figure 8] Block diagram showing an example configuration of the wireless communication system in the fourth embodiment. [Modes for carrying out the invention]

[0009] Each embodiment will be described below with reference to the drawings. Note that the following embodiments do not necessarily limit the present invention. Furthermore, not all combinations of features described in each embodiment are essential to the solution of the present invention.

[0010] [First Embodiment] Figure 1 shows an example of the configuration of the wireless communication system 1 in this embodiment. The wireless communication system 1 includes a wireless communication device 10 and a wireless communication device 20 that performs wireless communication with the wireless communication device 10. The wireless communication device 10 has differential transmission lines 101, 101', delay paths 105, 105', differential amplifier circuits 106, 106', and a transmitting circuit 107. The wireless communication device 20 has a coupler 200, a shaping circuit 201, and a receiving circuit 202. The differential transmission lines 101, 101' are provided on a dielectric substrate for the purpose of reducing the height. The differential transmission lines 101, 101' and the coupler 200 function as antennas for performing wireless communication by electromagnetic field coupling. The differential amplifier circuits 106, 106' and the transmitting circuit 107 function as communication control units for controlling wireless communication at the antennas.

[0011] <Configuration of wireless communication device 10> First, the configuration of the wireless communication device 10 will be described. The differential transmission line 101 is composed of conductors 111 and 112 formed in an arc shape around the rotation axis 30, and differential baseband signals, a differential positive signal and a differential negative signal, are input to each conductor. As shown in the figure, conductor 112 is positioned inward from conductor 111 when viewed from a reference direction parallel to the rotation axis 30. One end of conductors 111 and 112, the power supply section 102, is connected to the differential amplifier circuit 106 via lines 121 and 122. The other end of conductors 111 and 112, the termination section 104, is fitted with a termination resistor that is approximately equal to the characteristic impedance of the differential transmission line 101.

[0012] The differential transmission line 101' is configured in the same way as the differential transmission line 101. Since the differential transmission line 101' can be described in the same way as the differential transmission line 101 by adding a dash symbol "'" to the symbols used in the description of the differential transmission line 101, the explanation is omitted.

[0013] Still, the differential transmission lines 101, 101' need to ensure a connection that can communicate at all rotation angles with a coupler 200 that rotates relative to the rotation axis 30. Therefore, the power supply units 102, 102' and the termination units 104, 104' are arranged adjacent to each other as shown in the figure. Also, when the coupler 200 moves between the termination units 104 to 104' (or vice versa), the wiring lengths of the conductors 111, 111' and the wiring lengths of the conductors 112, 112' are wired so as to be substantially the same so that the phase of the signal transmitted to the coupler 200 is continuous. Here, the wiring length is also called the electrical length.

[0014] Here, delay paths 105, 105' are inserted into the lines 122, 122'. The delay paths 105, 105' are delay paths for suppressing the influence on communication due to the propagation delay difference caused by the difference in wiring length between the conductor 111 and the conductor 112 (or the conductor 111' and the conductor 112'). Here, the propagation delay difference is specifically the difference ΔT (= T1 - T2) between the propagation delay amount T1 from the power supply unit 102 to the termination unit 104 in the conductor 111 and the propagation delay amount T2 from the power supply unit 102 to the termination unit 104 in the conductor 112. Although the reason will be described later, the delay amount of the delay path 105 is set between ΔT × 0.1 and ΔT × 0.9. Preferably, it is set to ΔT × 0.5. Here, the delay path 105 is configured by a known method such as a meander. When the lines 121 and 122 are differential transmission lines, it is desirable to arrange them near the power supply unit 102 from the viewpoint of equalizing the characteristic impedance. The delay path 105' is the same as the delay path 105.

[0015] The differential amplifier circuits 106, 106' convert the data transmitted from the transmission circuit 107 into differential signals and output them to the differential transmission lines 101, 101'. In FIG. 1, although the transmission circuit 107 and the differential amplifier circuits 106, 106' are schematically connected by a single line, a divider such as a resistor divider or a Wilkinson power divider that divides high-frequency signals is inserted therebetween. Also, as another method, a fan-out circuit may be used for the differential amplifier circuits 106, 106'.

[0016] <Configuration of Wireless Communication Device 20> Next, the configuration of the wireless communication device 20 will be described. The coupler 200 is composed of conductors 211 and 212, and is arranged to be electromagnetically coupled with the differential transmission lines 101 and 101' as described above. Specifically, the conductor 211 is arranged to face the conductor 111 or the conductor 111', and the conductor 212 is arranged to face the conductor 112 or the conductor 112', and they are coupled by electromagnetic coupling. The wireless communication system 1 realizes wireless communication between the wireless communication device 10 and the wireless communication device 20 using electromagnetic coupling.

[0017] In this embodiment, the input impedance of the shaping circuit 201 is set to a high impedance Rrp such as several tens of kΩ. As a result, the input impedance Rrp is larger than the capacitance component generated by the coupling between the differential transmission lines 101 and 101' and the coupler 200, and components in a low frequency band are also transmitted to the shaping circuit 201. Therefore, the received waveform generated at the input end of the shaping circuit 201 is transmitted while maintaining a rectangular shape. In the shaping circuit 201, the received waveform is amplified to a voltage level detectable by the subsequent receiving circuit 202. Note that the shaping circuit 201 may have a reclocking function by clock-data recovery in addition to amplification.

[0018] <Configuration of Wireless Communication System 1> The wireless communication system 1 has a rotation control unit that relatively rotates the wireless communication device 10 and the wireless communication device 20 while maintaining the state where the coupler 200 and the differential transmission lines 101 and 101' face each other around the rotation axis 30.

[0019] With the configuration described above, the wireless communication system 1 in this embodiment realizes high-speed and low-profile wireless communication from the wireless communication device 10 to the wireless communication device 20 during rotation around the rotation axis 30.

[0020] <Effect by Insertion of Delay Path> Next, we will explain the effects of providing delay paths 105 and 105'. First, we will explain the problems in the case where delay paths 105 and 105' are not provided (conventional technology) using Figure 2. Figure 2 shows the signal waveforms of the differential signal positive supplied to conductor 111, the differential signal negative supplied to conductor 112, and the differential signal (= differential signal positive - differential signal negative). Figure 2(a) shows the signal waveform at the power supply section 102, Figure 2(b) shows the signal waveform at the central section 103, and Figure 2(c) shows the signal waveform at the termination section 103.

[0021] In the power supply section 102 shown in Figure 2(a), the phase of the positive differential signal and the phase of the negative differential signal coincide. However, a phase shift of ΔT × 0.5 occurs in the central section 103 shown in Figure 2(b), and a phase shift of ΔT occurs in the termination section 103 shown in Figure 2(c). As mentioned above, ΔT is the propagation delay difference caused by the difference in wiring length between conductor 111 and conductor 112. Due to the resulting phase shift, the waveform of the differential signal distorts as it approaches the termination section 104, as shown in the figure. It is presumed that this problem becomes more pronounced as the transmission speed of the differential signal increases. Note that in Figure 2, for the sake of explanation, the case in which the difference in propagation delay amount ΔT matches the time length of 1 bit of the baseband signal is explained, but the problem is not limited to this case.

[0022] Next, using Figure 3, the effects of inserting the delay path 105 in this embodiment will be explained. Note that the delay path 105' is similar, so its explanation will be omitted. Figure 3, like Figure 2, shows the signal waveforms of the differential signal positive supplied to conductor 111, the differential signal negative supplied to conductor 112, and the differential signal (= differential signal positive - differential signal negative). Figure 3(a) shows the signal waveform at the power supply section 102, Figure 3(b) shows the signal waveform at the central section 103, and Figure 3(c) shows the signal waveform at the termination section 103. Note that the delay amount of the delay path 105 is set to ΔT × 0.5. At the power supply section 102 shown in Figure 3(a), a phase difference of ΔT × 0.5 occurs between the phase of the differential signal positive and the phase of the differential signal negative, as set in the delay path 105. At the central section 103 shown in Figure 3(b), the phases coincide, and at the termination section 103 shown in Figure 3(c), the phase difference is suppressed to ΔT × 0.5. In other words, by inserting delay path 105, the maximum phase shift can be reduced to half of what it was before. This makes it possible to achieve twice the data transmission speed compared to the conventional method.

[0023] <Confirmation of effects through simulation> Figure 4 shows a specific example of the structure of the differential transmission lines 101, 101' and the coupler 200. Figure 4(a) is a perspective view of the differential transmission lines 101, 101' and the coupler 200, Figure 4(b) is a top view, and Figure 4(c) is a side view. The same reference numerals are used for the components described in Figure 1. The differential transmission lines 101, 101' are formed as copper patterns on the dielectric substrate 400, and the coupler 200 is positioned at a predetermined distance dZ in the Z direction from the differential transmission lines 101, 101'. The differential transmission lines 101, 101' are microstrip lines, and conductor 401 is a GND conductor that forms the reference potential. The dielectric substrate 400 has a hollow structure as shown in Figure 4, and a mechanical rotating shaft or an axial slip ring used for power transmission or low-speed communication applications is inserted into the central hole.

[0024] Figure 5 is a simulation graph illustrating the effects of this embodiment. The graph in Figure 5 shows the simulation results of the transfer characteristics (S-parameters, Sdd21) from the power supply section 102 (or 102') of the differential transmission line 101 (or 101') to the coupler 200 in the structure shown in Figure 4. The horizontal axis of the graph represents frequency, and the vertical axis represents gain. Figure 5(a) shows the transfer characteristics when the delay path 105 is not inserted (conventional case). Figure 5(b) shows the transfer characteristics when the delay path 105 with a delay amount ΔT × 0.5 is inserted (preferred case). Figure 5(c) shows the transfer characteristics when the delay path 105 with a delay amount ΔT × 0.833 is inserted. Figure 5 also shows the transfer characteristics when the coupler 200 is moved to positions at angles of 30 degrees, 90 degrees, and 150 degrees, as shown in Figure 4(b). The solid line shows the transfer characteristics at an angle of 30 degrees, the dotted line shows the transfer characteristics at an angle of 90 degrees, and the dashed line shows the transfer characteristics at an angle of 150 degrees. Figure 4(b) illustrates the case where the coupler 200 is positioned at an angle of 90 degrees.

[0025] The parameters in the simulation are described below. The inner diameter A of conductors 111 and 111' is 19.0 [mm], and the inner diameter B of conductors 112 and 112' is 26.1 [mm]. The wiring width W is 3.9 [mm], the transmission distance dZ is 1.0 [mm], and the thickness of the dielectric substrate is 3.2 [mm]. The differential impedance of the differential transmission lines 101 and 101' is 100 [Ω], and the differential impedance of the power supply section 102 and 102' is 100 [Ω]. The differential impedance of the termination section 104 and 104' is 100 [Ω], and the differential impedance of the coupler 200 is 22 [kΩ].

[0026] In the conventional case shown in Figure 5(a), the transmission characteristics are approximately flat up to about 5 GHz at an angle of 30 degrees, close to the power supply section 102 (or 102'). However, as the angle increases to 90 degrees and 150 degrees, and moves towards the termination section 104 (or 104'), the gain at frequencies above 1 GHz decreases sharply. For example, at an angle of 150 degrees, the gain difference between 1 GHz and 5 GHz widens to about 6.5 dB. On the other hand, when the delay path 105 (delay amount ΔT × 0.5) shown in Figure 5(b) is inserted, approximately flat transmission characteristics are maintained at all angles: 30 degrees, 90 degrees, and 150 degrees. For example, at an angle of 150 degrees, the gain difference between 1 GHz and 5 GHz remains below 1 dB. When the delay path 105 (delay amount ΔT × 0.833) shown in Figure 5(c) is inserted (when the phases between the differential pairs match at an angle of 150 degrees), approximately flat transmission characteristics are maintained at angles of 90 degrees and 150 degrees. However, it can be seen that the gain in the frequency band above 1 GHz is attenuated at an angle of 30 degrees. For example, the difference in gain between 1 GHz and 5 GHz at an angle of 30 degrees is approximately 3.3 dB. From the above results, it can be said that by inserting the delay path 105, the deterioration of the transmission characteristics of high-frequency components can be suppressed, and it is preferable to set the delay amount of the delay path 105 to ΔT × 0.5. With the configuration described above, it is possible to provide a wireless communication device applicable to a rotating movable part that enables faster data transmission and a lower profile than conventional devices.

[0027] In this embodiment, the input impedance Rrp of the shaping circuit 201 has been described as being set to a high impedance of several tens of kΩ, but it is not limited to this, and may be set to a low impedance such as 100 Ω for differential signals. In this case, the transmission characteristics from the differential transmission lines 101, 101' to the coupler 200 will be similar to those of a high-pass filter (HPF), with weak coupling at low frequencies and high coupling at high frequencies. Therefore, only high-frequency components of the signal from the differential transmission lines 101, 101' to the coupler 200 are transmitted. Specifically, an incomplete differential waveform of the signal input to the differential transmission lines 101, 101' (edge ​​signals generated during the rising and falling edges of the baseband signal input to the differential transmission lines 101, 101') is generated in the coupler 200. Therefore, the shaping circuit 201 is not a simple amplification circuit, but is realized by a circuit for restoring the above-mentioned differential waveform to a binary baseband signal of "1" or "0", such as a hysteresis comparator.

[0028] [Second Embodiment] Next, the wireless communication system 6 in the second embodiment will be described using Figure 6. In this embodiment, contrary to the first embodiment, a wireless communication system that transmits signals from the coupler 200 to the differential transmission lines 101, 101' will be described. The same reference numerals are used for components that are the same as those described in the first embodiment, and detailed explanations will be omitted. The wireless communication device 61 has differential transmission lines 101, 101', delay paths 105, 105', shaping circuits 616, 616', and a receiving circuit 617. The wireless communication device 62 has a coupler 200, a differential amplifier circuit 621, and a transmitting circuit 622. The differential transmission lines 101, 101' are provided on a dielectric substrate for the purpose of reducing the height. The specific structure of the wireless communication system 6 is the same as in Figure 4. Also, similar to the first embodiment, the wireless communication system 6 has a rotation control unit that rotates relative to the coupler 200 and the differential transmission lines 101, 101' while maintaining a state where they face each other around the rotation axis 30. The differential transmission lines 101, 101' and the coupler 200 function as antennas for wireless communication using electromagnetic field coupling. The shaping circuits 616, 616' and the receiving circuit 617 function as communication control units for controlling wireless communication at the antennas.

[0029] First, let's describe the configuration of the wireless communication device 62. The differential amplifier circuit 621 converts the data transmitted from the transmitting circuit 622 into a differential signal and outputs it to the coupler 200. The positive differential signal is input to conductor 211, and the negative differential signal is input to conductor 212.

[0030] Next, the configuration of the wireless communication device 61 will be described. Shaping circuits 616 and 616' are connected to differential transmission lines 101 and 101', respectively, via paths 121, 121', 122, and 122'. Shaping circuits 616 and 616' also shape the signals transmitted from the coupler 200 to the differential transmission lines 101 and 101' into a signal waveform that can be received by the subsequent receiving circuit 617, and output it. In this embodiment, termination resistors approximately equal to the characteristic impedance of the differential transmission lines 101 and 101' are mounted at the input of shaping circuits 616 and 616'. Paths 121 and 121' are also wired with characteristic impedances approximately equal to the characteristic impedance of the differential transmission lines 101 and 101'.

[0031] The transmission characteristics from coupler 200 to differential transmission lines 101, 101' are similar to those of a high-pass filter (HPF), with weak coupling at low frequencies and high coupling at high frequencies. Therefore, only high-frequency components are transmitted from coupler 200 to differential transmission lines 101, 101'. Specifically, an incomplete differential waveform of the signal input to coupler 200 is generated in differential transmission lines 101, 101'. Therefore, shaping circuits 616, 616' are implemented by circuits, such as hysteresis comparators, to restore the aforementioned differential waveform to a binary baseband signal of "1" or "0".

[0032] In this embodiment, as in the first embodiment, delay paths 105 and 105' are inserted into paths 122 and 122'. Delay paths 105 and 105' are delay paths that suppress the impact on communication due to the propagation delay difference caused by the difference in wiring length between conductor 111 and conductor 112 (or conductor 111' and conductor 112'). The delay amount of delay paths 105 and 105' is set between ΔT × 0.1 and ΔT × 0.9, preferably set to ΔT × 0.5. With the configuration described above, it is possible to achieve faster data transmission and a lower profile of the device than in the conventional method, while the wireless communication device 62 rotates relative to the wireless communication device 61.

[0033] [Third Embodiment] Next, the wireless communication system 7 in the third embodiment will be described using Figure 7. In this embodiment, a wireless communication system that transmits different parallel signals sent simultaneously in parallel will be described. Specifically, it is a system for improving the skew (time difference in arrival at the receiving circuit) caused by the difference in transmission path length of each coupling transmission path when coupling transmission paths for transmitting parallel signals are installed on a dielectric substrate for the purpose of reducing the height. Note that the same reference numerals are used for the same components as those described in the first embodiment, and detailed explanations will be omitted.

[0034] The wireless communication device 71 has coupling transmission lines 111, 111', 112, 112', delay paths 105, 105', amplification circuits 716_1, 716'_1, 716_2, 716'_2, and a transmitting circuit 717. The wireless communication device 72 has a coupler 211, a coupler 212, shaping circuits 721_1, 721_2, and a receiving circuit 722. In this embodiment, for the sake of explanation, the same structure as the conductors 211, 212 in the first embodiment is referred to as coupler 211, 212. The coupling transmission lines 111, 111', 112, 112' are provided on a dielectric substrate for the purpose of reducing the height. The specific structure of the wireless communication system 7 is the same as that shown in Figure 4. Furthermore, similar to the first embodiment, the wireless communication system 7 has a rotation control unit that rotates relative to the coupler 211 and coupling transmission lines 111, 111' and the coupler 212 and coupling transmission lines 112, 112' while maintaining a state in which they face each other.

[0035] First, the configuration of the wireless communication device 71 will be described. The transmitting circuit 717 has output terminals CH1 and CH2 and outputs two parallel signals that are transmitted simultaneously in parallel. Amplifier circuits 716_1 and 716'_1 amplify the data of CH1 output from the transmitting circuit 717 as a single-ended signal and output it to the coupling transmission lines 111 and 111'. Amplifier circuits 716_2 and 716'_2 amplify the data of CH2 output from the transmitting circuit 717 as a single-ended signal and output it to the coupling transmission lines 112 and 112'.

[0036] Next, the configuration of the wireless communication device 72 will be described. In this embodiment, as in the first embodiment, the input impedances of the shaping circuits 721_1 and 721_2 are set to a high impedance Rrp, such as several kΩ to tens of kΩ. As a result, the input impedance Rrp is greater than the capacitive components generated by the coupling of the coupling transmission line 111 and the coupler 211, and the coupling transmission line 112 and the coupler 212, even at low frequencies, and components in the low frequency band are also transmitted to the shaping circuits. As a result, the received waveform generated at the input terminals of the shaping circuits 721_1 and 721_2 is transmitted while maintaining its rectangular shape. The shaping circuits 721_1 and 721_2 amplify the received waveform to a voltage level that can be detected by the receiving circuit 722 located downstream. In addition to amplification, the shaping circuits 721_1 and 721_2 may also have a reclocking function by clock data recovery.

[0037] The receiving circuit 722 has input terminals CH1 and CH2, with CH1 receiving the output of the shaping circuit 721_1 and CH2 receiving the output of the shaping circuit 721_2. In this embodiment as in the first embodiment, delay paths 105 and 105' are inserted into paths 122 and 122'. Delay paths 105 and 105' are delay paths for suppressing skew between parallel signals caused by the propagation delay difference resulting from the difference in wiring length between conductor 111 and conductor 112 (or conductor 111' and conductor 112'). The delay amount of delay paths 105 and 105' is set between ΔT × 0.1 and ΔT × 0.9, preferably set to ΔT × 0.5. The reason for the delay amount is the same as in the first embodiment, so an explanation will be omitted, but the skew that occurs up to ΔT in the conventional configuration can be suppressed to ΔT × 0.5 with a suitable delay amount. As a result, the skew is improved, making it possible to increase the speed of parallel signal transmission compared to the conventional method. With the configuration described above, it is possible to transmit parallel signals from wireless communication device 71 to wireless communication device 72 at high speed while rotating relative to each other, and to achieve a low profile for the devices.

[0038] In this embodiment, for the sake of explanation, the case of transmitting 2 channels of parallel signals has been described, but it is not limited to this and can also be applied to cases with 3 or more channels. As an example, the case of 3 channels will be described. In the case of 3 channels, the coupling transmission lines are arranged in 3 lanes around the axis of rotation. The coupling transmission line arranged on the outermost circumference is called the first coupling transmission line, the coupling transmission line arranged in the center is called the second coupling transmission line, and the coupling transmission line arranged on the innermost circumference is called the third coupling transmission line. The propagation delay amount from the power supply part to the termination part of the first coupling transmission line is Tmax, the propagation delay amount from the power supply part to the termination part of the second coupling transmission line is Tmid, and the propagation delay amount from the power supply part to the termination part of the third coupling transmission line is Tmin. In this case, a delay path of (Tmax-Tmid) / 2 is preferably inserted into the second coupling transmission line, and a delay path of (Tmax-Tmin) / 2 is preferably inserted into the third coupling transmission line. Furthermore, the delay path for the second coupling transmission line does not need to be inserted if it is not necessary (if there are no issues with communication quality). In other words, it is also possible to configure the system to insert a delay path only in the coupling transmission line with the smallest propagation delay to suppress the propagation delay difference between it and the coupling transmission line with the largest propagation delay.

[0039] Furthermore, although each parallel signal was described as a single-ended signal in this embodiment, it may also be a differential signal. In that case, the coupling transmission line is composed of two conductors per channel, similar to the differential transmission lines 101 and 101' in the first embodiment. Also, although this embodiment describes a wireless communication system 7 that transmits signals from wireless communication device 71 to wireless communication device 72, it may also be configured to transmit signals from wireless communication device 72 to wireless communication device 71. In this case, the same approach as the configuration change from the first embodiment to the second embodiment is applied.

[0040] [Fourth Embodiment] Next, the wireless communication system 8 in the fourth embodiment will be described using Figure 8. The wireless communication system 8 in this embodiment has a configuration that eliminates the configuration on the differential transmission line 101' side from the wireless communication system 1 of the first embodiment. The same reference numerals are used for the same components as those described in the first embodiment, and detailed explanations will be omitted. The wireless communication system 8 has a rotation control unit that rotates back and forth relative to the coupler 200 and the differential transmission line 101 in an angle of 0 to 180 degrees, which is the range in which the coupler 200 and the differential transmission line 101 can maintain a state of facing each other around the rotation axis 30. The wireless communication device in this embodiment is suitable for application to rotating movable parts where reciprocating rotation is assumed (infinite rotation is not required), such as the tilt part of a pan-tilt camera. With the configuration described above, the wireless communication device 80 and the wireless communication device 20 rotate relative to each other, enabling faster data transmission and a lower profile of the device than in the conventional system.

[0041] In this embodiment, the rotation control unit enables reciprocating rotation between 0 and 180 degrees, but it can be set to any angle by adjusting the transmission path length of the differential transmission line 101.

[0042] [Other embodiments] In the above-described embodiment, the delay paths 105 and 105' were explained as being inserted into path 122 as meanders or the like, but the invention is not limited to this. For example, a delay difference may be generated by devising the dielectric constant of the peripheral components and the GND structure in the transmission paths of paths 121 and 122. Alternatively, a method may be used in which the differential signal positive and differential signal negative output in the differential amplifier circuits 106 and 106' are output with a desired phase difference.

[0043] Furthermore, although the differential transmission lines 101, 101' in the above-described embodiment were described as being formed in an arc shape with respect to the rotation axis 30, they are not limited to this shape. For example, any shape that ensures a communication-enabled coupling between the differential transmission lines 101, 101' and the coupler 200 is acceptable, such as a dodecagon.

[0044] Furthermore, although the differential transmission lines 101 and 101' in the above-described embodiment were described as microstrip lines, they are not limited to this. For example, they may be coplanar lines or microstrip lines with ground guards (GSSG structure).

[0045] Furthermore, although the differential transmission lines 101, 101' in the above-described embodiment were described as being provided on a dielectric substrate, the invention is not limited to this. For example, the differential transmission lines or coupled transmission lines may be formed on a flexible substrate or sheet metal.

[0046] Furthermore, although the signal transmitted in the above embodiment was described as a baseband signal, it is not limited to this, and may also be a modulated signal that changes the amplitude, frequency, and phase with respect to the carrier wave.

[0047] Furthermore, although the above-described embodiments mention a configuration in which a differential amplifier circuit or an amplifier circuit is inserted, this is not a mandatory configuration. For example, in the first embodiment, the output of the transmitting circuit 107 may be directly input to the differential transmission lines 101, 101'.

[0048] Furthermore, although the above-described embodiment described a structure in which the power supply sections 102 and 102' of the differential transmission lines 101 and 101' are adjacent and separated, the invention is not limited to this, and the power supply sections 102 and 102' may be electrically connected. For example, in the first embodiment, the differential amplifier circuit 106', path 121', and path 122' are eliminated, and the power supply sections 102 and 102' of the differential transmission lines 101 and 101' are electrically connected. In addition, the characteristic impedance of paths 121 and 122 is set to half the characteristic impedance of the differential transmission lines 101 and 101'.

[0049] Furthermore, the rotational control unit or reciprocating rotational control unit in the above-described embodiment is not essential, and the system can also be applied to systems that are driven by an external power source, such as human power. [Explanation of Symbols]

[0050] 1. Wireless communication system 10 Wireless communication devices 101 Differential transmission line 105 Delayed Route

Claims

1. A first antenna for performing wireless communication using electromagnetic field coupling with the antenna of another communication device, A communication control means for transmitting a signal via the first antenna, It has, The first antenna includes a first conductor having a shape along an arc centered on a predetermined axis, and a second conductor that, in a viewpoint in a reference direction parallel to the predetermined axis, is positioned inward from the first conductor with respect to the predetermined axis and has a shape along an arc centered on the predetermined axis. The communication control means inputs a first signal to one end of the first conductor and a second signal to one end of the second conductor, and the second signal has a predetermined delay amount relative to the first signal. The wireless communication device is characterized in that the predetermined delay amount is a value between 0.1 × ΔT and 0.9 × ΔT, where ΔT is the propagation delay difference resulting from the difference between the propagation delay from one end to the other end of the first conductor and the propagation delay from one end to the other end of the second conductor.

2. The wireless communication device according to claim 1, characterized in that the predetermined delay amount is set to 0.5 × ΔT.

3. The wireless communication device according to claim 1 or claim 2, further comprising rotation control means for rotating at least one of the first antenna and a second antenna for performing wireless communication by electromagnetic field coupling with the first antenna about a predetermined axis.

4. The wireless communication device according to any one of claims 1 to 3, characterized in that the other end of the first conductor and the other end of the second conductor have termination resistors.

5. The wireless communication device according to any one of claims 1 to 4, characterized in that the first signal and the second signal are differential signals with opposite phases to each other.

6. The wireless communication device according to any one of claims 1 to 5, wherein the communication control means is connected to the first conductor and the second conductor, and the communication control means includes a delay path having the predetermined delay amount.

7. The wireless communication device according to claim 6, characterized in that the delay path has a meander shape.

8. The wireless communication device according to any one of claims 1 to 7, characterized in that the first conductor and the second conductor of the first antenna are formed by a copper pattern on a dielectric substrate.

9. It further has a third antenna for performing wireless communication by electromagnetic field coupling with a second antenna of another wireless communication device, The communication control means performs control for transmitting a signal at the third antenna. The third antenna includes a third conductor having a shape along an arc centered on a predetermined axis, and a fourth conductor that, from a viewpoint in a reference direction parallel to the predetermined axis, is positioned inward from the third conductor with respect to the predetermined axis and has a shape along an arc centered on the predetermined axis. A third signal is input to one end of the third conductor, and a fourth signal is input to one end of the fourth conductor with a predetermined delay amount. The wireless communication device according to any one of claims 1 to 8, characterized in that the other end of the third conductor is located near the other end of the first conductor, and the other end of the fourth conductor is located near the other end of the second conductor.

10. The wireless communication device according to any one of claims 1 to 9, characterized in that the first signal and the second signal are baseband signals.

11. The wireless communication device according to any one of claims 1 to 10, characterized in that the first signal and the second signal are modulated signals.

12. A first antenna for performing wireless communication using electromagnetic field coupling with the antenna of another communication device, It includes a communication control means for receiving a signal via the first antenna, The first antenna includes a first conductor having a shape along an arc centered on a predetermined axis, and a second conductor that, in a viewpoint in a reference direction parallel to the predetermined axis, is positioned inward from the first conductor with respect to the predetermined axis and has a shape along an arc centered on the predetermined axis. The communication control means includes a delay path having a predetermined delay amount, The wireless communication device is characterized in that the predetermined delay amount is a value between 0.1 × ΔT and 0.9 × ΔT, where ΔT is the propagation delay difference resulting from the difference between the propagation delay from one end to the other end of the first conductor and the propagation delay from one end to the other end of the second conductor.

13. The wireless communication device according to claim 12, characterized in that the predetermined delay amount is set to 0.5 × ΔT.

14. The wireless communication device according to any one of claims 12 to 13, characterized in that the other end of the first conductor and the other end of the second conductor have termination resistors.

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