Rotary coupler

Abstract

This rotary coupler uses electromagnetic coupling to transmit and receive signals between a fixed part (10A) and a rotating part (20A) that is rotatably supported with respect to the fixed part (10A). The fixed part (10A) has waveguides (12a, 12b) that have the same diameter and are arranged around a central axis (O) so as to face each other in an arc shape, a lossy medium (11) to which one end of the waveguide (12a) and one end of the waveguide (12b) are connected, and a transmission / reception circuit (13) to which the other end of the waveguide (12a) and the other end of the waveguide (12b) are connected. The rotating part (20A) has a coupling part (21) that rotates about the central axis (O) and electromagnetically couples with at least one of the waveguides (12a, 12b), and a transmitting / receiving circuit (22) that is connected to the coupling part (21) and transmits / receives signals to / from the transmitting / receiving circuit (13).

Description

Rotary Coupler

[0001] The present disclosure relates to rotary couplers.

[0002] Conventionally, a rotary coupler has been provided that includes a fixed portion and a rotating portion that rotates relative to the fixed portion. This rotary coupler allows signals to be transmitted and received between the fixed portion and the rotating portion. An example of such a conventional rotary coupler is disclosed in Patent Document 1.

[0003] Special Publication No. 2008-533786

[0004] The rotary coupler disclosed in Patent Document 1 includes microstrip lines in both a fixed portion and a rotating portion. The microstrip lines provided in the fixed portion and the microstrip lines provided in the rotating portion have different lengths, are arc-shaped, and are arranged opposite each other. The rotary coupler disclosed in Patent Document 1 enables transmission and reception of signals between the two microstrip lines by electromagnetically coupling the microstrip lines of the fixed portion and the microstrip lines of the rotating portion while rotating the rotating portion relative to the fixed portion.

[0005] When the microstrip line of the rotating section passes (rotates) a position facing the termination of the microstrip line of the fixed section, the microstrip line of the fixed section corresponding to the microstrip line of the rotating section temporarily disappears. This causes the electromagnetic coupling force between the two microstrip lines to become very weak, resulting in a decrease in gain. As a result, the rotary coupler disclosed in Patent Document 1 may not be able to transmit or receive signals at all rotation angles of the rotating section.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a rotary coupler that can transmit and receive signals between a fixed part and a rotating part at all rotation angle positions of the rotating part.

[0007] A rotary coupler according to the present disclosure is a rotary coupler that uses electromagnetic coupling to transmit and receive signals between a fixed part and a rotating part that is rotatably supported relative to the fixed part, wherein the fixed part includes a first waveguide and a second waveguide that have the same diameter, are arc-shaped, and are arranged facing each other around a central axis, a lossy medium to which one end of the first waveguide and one end of the second waveguide are connected, and a fixed-side transmitting and receiving circuit to which the other end of the first waveguide and the other end of the second waveguide are connected, and the rotating part rotates around the central axis as the center of rotation and includes a coupling part that electromagnetically couples with at least one of the first waveguide and the second waveguide, and a rotating-side transmitting and receiving circuit that is connected to the coupling part and transmits and receives signals between the fixed-side transmitting and receiving circuit.

[0008] According to the present disclosure, signals can be transmitted and received between the fixed part and the rotating part at all rotation angle positions of the rotating part.

[0009] 1 is a schematic diagram of a rotary coupler according to a first embodiment. FIG. 2A is a schematic diagram of the fixed section. FIG. 2B is a schematic diagram of the rotary section. FIG. 3A is a diagram showing the operation of the rotary coupler according to the first embodiment. FIG. 3A is a diagram showing a state in which the coupling section of the rotary section is not facing the lossy medium of the fixed section. FIG. 3B is a diagram showing a state in which the coupling section of the rotary section is facing the lossy medium of the fixed section. FIG. 4A is a schematic diagram of the fixed section. FIG. 4B is a schematic diagram of the rotary section. FIG. 6A is an exploded perspective view of a rotary coupler according to a third embodiment. FIG. 6B is a diagram showing the configuration of a rotary coupler according to the third embodiment. FIG. 6A is a plan view of the rotary coupler. FIG. 6B is a cross-sectional view taken along the arrows VI-VI in FIG. 6A.

[0010] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0011] First Embodiment A rotary coupler according to a first embodiment will be described with reference to FIGS.

[0012] First, the configuration of a rotary coupler according to the first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic diagram of the rotary coupler according to the first embodiment. Fig. 2 is a diagram showing the configurations of a fixed unit 10A and a rotating unit 20A according to the first embodiment.

[0013] 1, the rotary coupler according to the first embodiment includes a fixed portion 10A and a rotating portion 20A. This rotary coupler transmits and receives signals (e.g., high-frequency signals) between the fixed portion 10A and the rotating portion 20A using electromagnetic coupling.

[0014] The fixed part 10A and the rotating part 20A are arranged coaxially and are separated from each other with a predetermined gap in the axial direction. The rotating part 20A rotates around the central axis O (see FIG. 2) of the rotary coupler relative to the fixed part 10A. In FIG. 2B, the arrow surrounding the central axis O indicates the rotation direction of the rotating part 20A. That is, the rotating part 20A can rotate both clockwise and counterclockwise.

[0015] 1 and 2, the fixed unit 10A has a lossy medium 11, a first waveguide 12a (hereinafter simply referred to as waveguide 12a), a second waveguide 12b (hereinafter simply referred to as waveguide 12b), and a transmitting / receiving circuit 13. The transmitting / receiving circuit 13 constitutes a fixed-side transmitting / receiving circuit.

[0016] The waveguides 12a and 12b are both arc-shaped and have the same diameter. The waveguides 12a and 12b are arranged on the same plane and coaxially with the central axis O. Therefore, the waveguides 12a and 12b are arranged to face each other, and as a whole, they form a substantially circular arc shape.

[0017] One end of the waveguide 12a and one end of the waveguide 12b are connected via a lossy medium 11. Meanwhile, the other end of the waveguide 12a and the other end of the waveguide 12b are connected to a transmitting / receiving circuit 13, respectively.

[0018] 1 and 2, the rotating part 20A has a coupling part 21 and a transmitting / receiving circuit 22. The transmitting / receiving circuit 22 constitutes a rotating-side transmitting / receiving circuit.

[0019] The coupling portion 21 is a transmission line. The coupling portion 21 is arc-shaped and has the same diameter as the diameter D of the waveguides 12a and 12b. The length of the coupling portion 21 is different from the lengths of the waveguides 12a and 12b. Specifically, the length of the coupling portion 21 is shorter than the lengths of the waveguides 12a and 12b. The coupling portion 21 is also arranged coaxially with the central axis O. That is, the waveguides 12a and 12b and the coupling portion 21 are arranged coaxially. Furthermore, the coupling portion 21 is connected to the transmission / reception circuit 22.

[0020] The coupling portion 21 rotates together with the rotation of the rotating portion 20A about the central axis O. At this time, the coupling portion 21 faces at least one of the waveguides 12a and 12b in the axial direction. Therefore, the coupling portion 21 is electrically coupled to at least one of the waveguides 12a and 12b. As a result, signals are transmitted and received between the transmission / reception circuit 13 of the fixed portion 10A and the transmission / reception circuit 22 of the rotating portion 20A.

[0021] Next, the operation of the rotary coupler according to the first embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram showing the operation of the rotary coupler according to the first embodiment. Note that the open arrows shown in Figs. 1 and 3 indicate the flow of signals.

[0022] 3A is a diagram showing a state in which the coupling portion 21 of the rotating portion 20A does not face the lossy medium 11 of the fixed portion 10A. As shown in this Fig. 3A, when the coupling portion 21 of the rotating portion 20A does not face the lossy medium 11 of the fixed portion 10A (in other words, the coupling portion 21 is disposed offset with respect to the lossy medium 11), the signal output from the transmission / reception circuit 13 of the fixed portion 10A is in phase and is split into two signals, one to the other end of the waveguide 12a and the other end of the waveguide 12b.

[0023] The signal distributed to the other end of waveguide 12a is transmitted along the length of waveguide 12a and then absorbed by lossy medium 11. Meanwhile, the signal distributed to the other end of waveguide 12b is transmitted along the length of waveguide 12b and then reaches coupling unit 21. Therefore, the signal that reaches coupling unit 21 is electromagnetically coupled with coupling unit 21 and transmitted to transmission / reception circuit 22. The signal that travels from transmission / reception circuit 13, via waveguide 12b, through coupling unit 21, and to transmission / reception circuit 22 is transmitted as a wideband signal without discontinuity in the electromagnetic field distribution.

[0024] 3B is a diagram showing a state in which the coupling portion 21 of the rotating portion 20A faces the lossy medium 11 of the fixed portion 10A. As shown in this Fig. 3B, when the coupling portion 21 of the rotating portion 20A faces the lossy medium 11 of the fixed portion 10A (in other words, when the coupling portion 21 is located directly above the lossy medium 11), the signal output from the transmission / reception circuit 13 of the fixed portion 10A is in phase with and is split into two signals, one for the other end of the waveguide 12a and the other end of the waveguide 12b.

[0025] The signal distributed to the other end of waveguide 12a is transmitted along the length of waveguide 12a and then reaches coupling unit 21. On the other hand, the signal distributed to the other end of waveguide 12b is transmitted along the length of waveguide 12b and then reaches coupling unit 21.

[0026] Here, when the lengths of waveguides 12a and 12b are the same, or when the difference between the lengths of waveguides 12a and 12b is an integer multiple of the signal wavelength, the signal transmitted from waveguide 12a and the signal transmitted from waveguide 12b are combined in phase because waveguides 12a and 12b are electromagnetically coupled to coupling unit 21. The combined signal is then transmitted to transmission / reception circuit 22. Such a signal traveling from transmission / reception circuit 13, via waveguides 12a and 12b, through coupling unit 21, and to transmission / reception circuit 22 is transmitted as a wideband signal without discontinuity in the electromagnetic field distribution.

[0027] In the operation of the rotary coupler described above, the operation of receiving a signal transmitted from the transmission / reception circuit 13 of the fixed part 10A by the transmission / reception circuit 22 of the rotating part 20A has been explained. However, this explanation provides a sufficient understanding of the operation of receiving a signal transmitted from the transmission / reception circuit 22 of the rotating part 20A by the transmission / reception circuit 13 of the fixed part 10A, and therefore the explanation thereof will be omitted.

[0028] Therefore, the rotary coupler according to the first embodiment does not cause discontinuity in the electromagnetic field distribution when coupling unit 21 is disposed at a rotational angle position other than directly above lossy medium 11. Furthermore, when coupling unit 21 is disposed at a rotational angle position corresponding to directly above lossy medium 11, the rotary coupler according to the first embodiment combines signals from both waveguides 12a and 12b in phase with coupling unit 21 due to electromagnetic coupling between waveguides 12a and 12b and coupling unit 21. Therefore, the rotary coupler according to the first embodiment can transmit and receive signals between fixed unit 10A and rotating unit 20A regardless of the rotational angle position of rotating unit 20A.

[0029] As described above, the rotary coupler according to the first embodiment is a rotary coupler that uses electromagnetic coupling to transmit and receive signals between a fixed unit 10A and a rotating unit 20A that is rotatably supported relative to the fixed unit 10A. The fixed unit 10A includes waveguides 12a and 12b that have the same diameter, are arc-shaped, and are arranged facing each other around a central axis O, a lossy medium 11 to which one end of the waveguide 12a is connected to one end of the waveguide 12b, and a transmission / reception circuit 13 to which the other end of the waveguide 12a is connected to the other end of the waveguide 12b. The rotating unit 20A rotates around the central axis O as the center of rotation and includes a coupling unit 21 that electromagnetically couples with at least one of the waveguides 12a and 12b, and a transmission / reception circuit 22 that is connected to the coupling unit 21 and transmits and receives signals to and from the transmission / reception circuit 13. Therefore, the rotary coupler according to the first embodiment can transmit and receive signals between the fixed portion 10A and the rotating portion 20A at all rotational angle positions of the rotating portion 20A.

[0030] Embodiment 2 A rotary coupler according to embodiment 2 will be described with reference to Fig. 4. Fig. 4 is a diagram showing the configuration of a fixed section 10B and a rotating section 20A in a rotary coupler according to embodiment 2. Note that components having the same functions as those described in embodiment 1 above are given the same reference numerals, and their description will be omitted.

[0031] As shown in Fig. 4, the rotary coupler according to the second embodiment includes a fixed portion 10B and a rotating portion 20A. This rotary coupler transmits and receives signals between the fixed portion 10B and the rotating portion 20A using electromagnetic coupling. That is, the rotary coupler according to the second embodiment has a structure including a fixed portion 10B instead of the fixed portion 10A of the rotary coupler according to the first embodiment.

[0032] As shown in FIG. 4A, the fixed portion 10B includes a lossy medium 11, a waveguide 12a, a waveguide 12b, a branch portion 12c, and a transmitting / receiving circuit 13.

[0033] In the fixed portion 10B, the waveguide 12a, the waveguide 12b, and the branch portion 12c are assumed to be microstrip lines, and the lossy medium 11 is assumed to be a terminator. Therefore, the rotary coupler can easily manufacture the waveguide 12a, the waveguide 12b, and the branch portion 12c. Furthermore, by using the lossy medium 11 as a terminator, the rotary coupler can prevent unwanted signal reflection at the ends of the microstrip lines (the tips of the waveguides 12a and 12b).

[0034] The branch portion 12c is formed in a T-shape or a bifurcated shape. The base end of the branch portion 12c is connected to the transmitting / receiving circuit 13. The two ends of the branch portion 12c are connected to the other end of the waveguide 12a and the other end of the waveguide 12b, respectively.

[0035] As shown in Fig. 4B, the rotating unit 20A has a coupling unit 21 and a transmitting / receiving circuit 22. In the rotary coupler according to the second embodiment, the coupling unit 21 is assumed to be a probe using a microstrip line. In this case, the position of the probe is disposed on the rotation radius (diameter dimension D) of the lossy medium 11, the waveguide 12a, the waveguide 12b, and the branching unit 12c. In this case, the rotary coupler is capable of adjusting the position of the probe as appropriate, as long as it is within a range in which a desired amount of electromagnetic coupling can be obtained.

[0036] The transmission line used in the probe may be a line configuration other than a microstrip line. It is also preferable that the transmission line used in the probe does not resonate at the frequency used. For example, if the transmission line is linear, the length of the transmission line may be set to be equal to λ / 2.

[0037] Therefore, the rotary coupler according to the second embodiment does not cause discontinuity in the electromagnetic field distribution when coupling unit 21 is disposed at a rotational angle position other than directly above lossy medium 11. Furthermore, when coupling unit 21 is disposed at a rotational angle position corresponding to directly above lossy medium 11, the rotary coupler according to the second embodiment combines signals from both waveguides 12a and 12b in phase with coupling unit 21 due to electromagnetic coupling between waveguides 12a and 12b and coupling unit 21. Therefore, the rotary coupler according to the second embodiment can transmit and receive signals between fixed unit 10B and rotating unit 20A regardless of the rotational angle position of rotating unit 20A.

[0038] As described above, the rotary coupler according to the second embodiment is a rotary coupler that uses electromagnetic coupling to transmit and receive signals between a fixed unit 10B and a rotating unit 20A that is rotatably supported relative to the fixed unit 10B. The fixed unit 10B includes waveguides 12a and 12b that have the same diameter, are arc-shaped, and are arranged facing each other around a central axis O, a lossy medium 11 to which one end of the waveguide 12a is connected to one end of the waveguide 12b, and a transmission / reception circuit 13 to which the other end of the waveguide 12a is connected to the other end of the waveguide 12b. The rotating unit 20A rotates around the central axis O as the center of rotation and includes a coupling unit 21 that electromagnetically couples with at least one of the waveguides 12a and 12b, and a transmission / reception circuit 22 that is connected to the coupling unit 21 and transmits and receives signals to and from the transmission / reception circuit 13. Therefore, the rotary coupler according to the second embodiment can transmit and receive signals between the fixed portion 10B and the rotating portion 20A at all rotational angle positions of the rotating portion 20A.

[0039] Embodiment 3 A rotary coupler according to embodiment 3 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is an exploded perspective view of the rotary coupler according to embodiment 3. Fig. 6 is a diagram showing the configuration of the rotary coupler according to embodiment 3. Note that components having the same functions as those described in embodiment 1 above are given the same reference numerals, and their description will be omitted.

[0040] 5 and 6, the rotary coupler according to the third embodiment includes a fixed portion 10C and a rotating portion 20C. This rotary coupler transmits and receives signals between the fixed portion 10C and the rotating portion 20C using electromagnetic coupling.

[0041] The fixed unit 10C has a lossy medium 11, a first fixed-side half waveguide 121 of the waveguide 12a (hereinafter simply referred to as the fixed-side half waveguide 121), a second fixed-side half waveguide 123 of the waveguide 12b (hereinafter simply referred to as the fixed-side half waveguide 123), and a transmitting / receiving circuit 13. In the fixed unit 10C, the lossy medium 11 is assumed to be a radio wave absorber.

[0042] In contrast, the rotating part 20C has a coupling part 21, a transmitting / receiving circuit 22, a first rotating-side half waveguide 122 of the waveguide 12a (hereinafter simply referred to as the rotating-side half waveguide 122), and a second rotating-side half waveguide 124 of the waveguide 12b (hereinafter simply referred to as the rotating-side half waveguide 124).

[0043] That is, the waveguide 12a has a half structure (or a divided structure) in the axial direction, with the fixed portion 10C and the rotating portion 20C as the boundary. This waveguide 12a is divided into a fixed-side half waveguide 121 and a rotating-side half waveguide 122. The fixed-side half waveguide 121 and the rotating-side half waveguide 122 are both groove-shaped and are arranged so that their openings face each other in the axial direction. Therefore, a hollow portion that serves as a waveguide is formed between them.

[0044] On the other hand, the waveguide 12b has a half structure (or a divided structure) in the axial direction, with the fixed portion 10C and the rotating portion 20C as the boundary. This waveguide 12b is divided into a fixed-side half waveguide 123 and a rotating-side half waveguide 124. The fixed-side half waveguide 123 and the rotating-side half waveguide 124 are both groove-shaped and are arranged so that their openings face each other in the axial direction. Therefore, a hollow portion that serves as a waveguide is formed between them.

[0045] One end of the fixed-side half waveguide 121 and one end of the fixed-side half waveguide 123 are connected via a lossy medium 11. The other end of the fixed-side half waveguide 121 and the other end of the fixed-side half waveguide 123 are each connected to the transmission / reception circuit 13. Note that the other end of the fixed-side half waveguide 121 and the other end of the fixed-side half waveguide 123 may be connected to the transmission / reception circuit 13 via a branch portion 12c.

[0046] Furthermore, one end of the rotation-side half waveguide 122 and one end of the rotation-side half waveguide 124 are connected via a coupling portion 21. The other end of the fixed-side half waveguide 121 and the other end of the fixed-side half waveguide 123 are connected to each other.

[0047] Therefore, the rotary coupler according to the third embodiment does not cause discontinuity in the electromagnetic field distribution when coupling unit 21 is disposed at a rotational angle position other than directly above lossy medium 11. Furthermore, when coupling unit 21 is disposed at a rotational angle position corresponding to directly above lossy medium 11, the rotary coupler according to the third embodiment combines signals from both waveguides 12a and 12b in phase with coupling unit 21 due to electromagnetic coupling between waveguides 12a and 12b and coupling unit 21. Therefore, the rotary coupler according to the third embodiment can transmit and receive signals between fixed unit 10C and rotating unit 20C regardless of the rotational angle position of rotating unit 20C.

[0048] As described above, the rotary coupler according to the third embodiment is a rotary coupler that uses electromagnetic coupling to transmit and receive signals between a fixed unit 10C and a rotating unit 20C that is rotatably supported relative to the fixed unit 10C, and includes waveguides 12a and 12 having a split structure that have the same diameter, are arc-shaped, and are arranged facing each other around a central axis O between the fixed unit 10C and the rotating unit 20C. The fixed unit 10C includes a fixed-side half-waveguide 121 that constitutes the waveguide 12a, a fixed-side half-waveguide 123 that constitutes the waveguide 12b, a lossy medium 11 to which one end of the fixed-side half-waveguide 121 and one end of the fixed-side half-waveguide 123 are connected, and a transmission / reception circuit 13 to which the other end of the fixed-side half-waveguide 121 and the other end of the fixed-side half-waveguide 123 are connected. The rotating unit 20C includes a rotating-side half waveguide 122 that constitutes the waveguide 12a, a rotating-side half waveguide 124 that constitutes the waveguide 12b, a coupling unit 21 that connects one end of the rotating-side half waveguide 122 to one end of the rotating-side half waveguide 124 and rotates about the central axis O as the center of rotation, and that electromagnetically couples with at least one of the fixed-side half waveguide 121 and the fixed-side half waveguide 123, and a transmitting / receiving circuit 22 that is connected to the coupling unit 21 and transmits / receives signals to / from the transmitting / receiving circuit 13. Therefore, the rotary coupler according to the third embodiment can transmit / receive signals between the fixed unit 10C and the rotating unit 20C at all rotation angle positions of the rotating unit 20C.

[0049] It should be noted that within the scope of the present disclosure, the embodiments may be freely combined, or any component in each embodiment may be modified, or any component in each embodiment may be omitted.

[0050] The rotary coupler according to the present disclosure is suitable for use in rotary couplers and the like, since it is possible to transmit and receive signals between the fixed part and the rotating part at all rotation angle positions of the rotating part by providing a lossy medium in the fixed part.

[0051] 10A, 10B, 10C Fixed portion, 11 Lossy medium, 12a First waveguide, 121 First fixed-side half waveguide, 122 First rotating-side half waveguide, 12b Second waveguide, 123 Second fixed-side half waveguide, 124 Second rotating-side half waveguide, 12c Branching portion, 13 Transmitting / receiving circuit, 20A, 20C Rotating portion, 21 Coupling portion, 22 Transmitting / receiving circuit, D Diameter dimension, O Central axis.

Claims

1. A rotary coupler that uses electromagnetic coupling to transmit and receive signals between a fixed part and a rotating part that is rotatably supported on the fixed part, wherein the fixed part has: a first waveguide and a second waveguide that have the same diameter, are arc-shaped, and are arranged facing each other about a central axis; a lossy medium to which one end of the first waveguide and one end of the second waveguide are connected; and a fixed-side transmitting and receiving circuit to which the other end of the first waveguide and the other end of the second waveguide are connected; and the rotating part has: a coupling part that rotates about the central axis as the center of rotation, and that electromagnetically couples with at least one of the first waveguide and the second waveguide, and a rotating-side transmitting and receiving circuit that is connected to the coupling part and transmits and receives signals between the fixed-side transmitting and receiving circuit.

2. A rotary coupler that uses electromagnetic coupling to transmit and receive signals between a fixed part and a rotating part that is rotatably supported relative to the fixed part, comprising a first waveguide and a second waveguide that have the same diameter, are arranged in an arc shape, and are arranged facing each other with a central axis as the center between the fixed part and the rotating part, the fixed part has: a first fixed-side half-waveguide that constitutes the first waveguide; a second fixed-side half-waveguide that constitutes the second waveguide; a lossy medium to which one end of the first fixed-side half-waveguide and one end of the second fixed-side half-waveguide are connected; and a fixed-side transmission / reception circuit to which the other end of the first fixed-side half-waveguide and the other end of the second fixed-side half-waveguide are connected, and the rotating part has: a first rotating-side half-waveguide that constitutes the first waveguide; a second rotating-side half-waveguide constituting the second waveguide; a coupling section to which one end of the first rotating-side half-waveguide and one end of the second rotating-side half-waveguide are connected and which rotates about the central axis as a center of rotation and which electromagnetically couples with at least one of the first fixed-side half-waveguide and the second fixed-side half-waveguide; and a rotating-side transmitting and receiving circuit connected to the coupling section and which transmits and receives signals between the rotating and fixed-side transmitting and receiving circuit.

3. A rotary coupler according to claim 1 or 2, characterized in that the length of said first waveguide and the length of said second waveguide are the same.

4. A rotary coupler according to claim 1 or 2, characterized in that the difference between the length of said first waveguide and the length of said second waveguide is an integer multiple of the wavelength of the signal.

5. A rotary coupler according to any one of claims 1, 3 and 4, characterized in that the first waveguide and the second waveguide are microstrip lines.

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