In-vehicle antenna device

Abstract

Provided is an in-vehicle antenna device 1 including a plurality of antenna substrates 20 and a plurality of optical fibers 10. Each optical fiber 10 includes an extra-length portion 11 including a portion of the optical fiber 10 in which two or more different points on the optical fiber 10 are arranged so as to overlap each other.

Description

Vehicle antenna device

[0001] The present invention relates to an in-vehicle antenna device. For designated states where incorporation by reference of documents is permitted, the contents of Japanese Patent Application No. 2024-134279, filed in Japan on August 9, 2024, are incorporated herein by reference and made a part of the present specification.

[0002] 2. Description of the Related Art A known in-vehicle sensor module is one in which a plurality of radar antenna devices connected to optical fibers are arranged in an array (see, for example, Patent Document 1).

[0003] US Patent Application Publication No. 2022 / 0231406

[0004] The sensor module described in Patent Document 1 detects the speed of an object based on the phase difference between signals transmitted through optical fibers connected to each radar antenna device. Therefore, in the sensor module described in Patent Document 1, the lengths of the optical fibers are required to be equal to each other to prevent phase shifts caused by differences in the lengths of the optical fibers. However, if the lengths of the optical fibers are configured to be equal to each other, some optical fibers must be relatively long compared to the minimum physical length required to connect the light source and the radar antenna device. This makes it difficult to handle the optical fibers during vehicle assembly, which can lead to problems such as the optical fibers breaking. Furthermore, because the optical fibers are relatively long, they are prone to come into contact with surrounding structures due to vibrations caused by vehicle movement, which can lead to problems such as the optical fibers breaking.

[0005] The problem to be solved by the present invention is to provide an in-vehicle antenna device that can suppress the occurrence of breakage of the optical fiber.

[0006] [1] Aspect 1 of the present invention is an in-vehicle antenna device comprising a plurality of antenna substrates and a plurality of optical fibers respectively connected to the plurality of antenna substrates, each of the optical fibers having an excess length including a portion of the optical fiber arranged so that two or more different points on the optical fiber overlap each other.

[0007] [2] Aspect 2 of the present invention may be an in-vehicle antenna device according to aspect 1, wherein the excess length portion is a portion provided to make the lengths of the plurality of optical fibers equal to each other.

[0008] [3] A third aspect of the present invention is the in-vehicle antenna device according to the first or second aspect, wherein the excess length portion may include a wound portion of the optical fiber.

[0009] [4] Aspect 4 of the present invention may be an in-vehicle antenna device according to any one of aspects 1 to 3, wherein the plurality of excess length portions are arranged in a stacked manner at predetermined positions on the in-vehicle antenna device.

[0010] [5] Aspect 5 of the present invention may be an in-vehicle antenna device according to any one of aspects 1 to 4, comprising a housing that accommodates the antenna substrate and the optical fiber, the excess length portion including a first excess length portion that is accommodated in the housing, and the housing comprising an antenna accommodating section that accommodates the antenna substrate and an excess length storage section that stores the first excess length portion.

[0011] [6] Aspect 6 of the present invention is an in-vehicle antenna device according to aspect 5, wherein the excess length storage section may be provided at an end of the housing along the longitudinal direction.

[0012] [7] A seventh aspect of the present invention is an in-vehicle antenna device according to the fifth or sixth aspect, wherein the excess length portion may include a second excess length portion arranged outside the housing.

[0013] [8] A seventh aspect of the present invention may be an in-vehicle antenna device according to any one of the fifth to seventh aspects, which is an in-vehicle antenna device including a flexible printed wiring board electrically connected to the antenna substrate and housed in the housing.

[0014] [9] Aspect 9 of the present invention may be an in-vehicle antenna device according to any one of aspects 1 to 8, wherein the antenna substrate comprises an antenna element and an optical-electrical conversion circuit electrically connected to the antenna element and optically connected to the optical fiber.

[0015]

[10] A tenth aspect of the present invention is an in-vehicle antenna device according to any one of claims 1 to 9, wherein the plurality of antenna substrates may be arranged at intervals.

[0016]

[11] Aspect 11 of the present invention is an in-vehicle antenna device according to any one of aspects 1 to 10, wherein the in-vehicle antenna device includes an optical connector provided at an end of the optical fiber opposite to the end connected to the antenna substrate, and the lengths of each of the optical fibers from the antenna substrate to the optical connector may be equal to each other.

[0017] In the present invention, each of the optical fibers connected to the multiple antenna substrates has an excess length. This makes it easier to handle the optical fibers during vehicle assembly and prevents the optical fibers from coming into contact with surrounding structures while the vehicle is running. Therefore, the in-vehicle antenna device according to the present invention can prevent breakage of the optical fibers.

[0018] Fig. 1 is a front view of a vehicle equipped with an on-board antenna device according to an embodiment of the present invention. Fig. 2 is a plan view of the on-board antenna device according to an embodiment of the present invention. Fig. 3 is an enlarged cross-sectional view of part III-III in Fig. 2. Fig. 4 is a configuration diagram of an obstacle detection system according to an embodiment of the present invention.

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] FIG. 1 is a front view of a vehicle 100 equipped with an in-vehicle antenna device 1 according to this embodiment, FIG. 2 is a plan view of the in-vehicle antenna device 1 according to this embodiment, and FIG. 3 is an enlarged cross-sectional view of part III-III in FIG.

[0021] 1, the in-vehicle antenna device 1 in this embodiment is attached to a front bumper 101 of a vehicle 100. The in-vehicle antenna device 1 is a millimeter wave radar device that transmits and receives radio waves (so-called millimeter waves) with a frequency of 30 to 300 GHz and detects the distance to a measurement target such as an obstacle, the speed of the measurement target, the angle of the measurement target, etc. by analyzing the received waves.

[0022] In this embodiment, one in-vehicle antenna device 1 is provided along a direction horizontal to the front bumper 101 of the vehicle 100, but the installation location and number of in-vehicle antenna devices 1 are not particularly limited to this. For example, one in-vehicle antenna device 1 may be provided along a direction perpendicular to the front bumper 101 of the vehicle 100. Alternatively, the vehicle 100 may be provided with two in-vehicle antenna devices 1, one of which is provided along a direction horizontal to the front bumper 101 and the other of which is provided along a direction perpendicular to the front bumper 101. Furthermore, although not particularly shown, the in-vehicle antenna device 1 may be provided on the rear bumper, hood, door, roof, window glass, etc. of the vehicle 100.

[0023] As shown in FIGS. 2 and 3 , the vehicle-mounted antenna device 1 includes a plurality of antenna substrates 20 , a plurality of optical fibers 10 , a flexible printed wiring board 30 , a housing 40 , and an optical connector 50 .

[0024] The antenna substrate 20, the optical fiber 10, and the flexible printed wiring board 30 are housed in a housing 40. The housing 40 includes a main body 41 and a resin cover 42. In this embodiment, the material constituting the main body 41 is not particularly limited and may be a metal material or a resin material. As shown in FIG. 3 , the upper opening of the main body 41 is covered by the resin cover 42. The material constituting the resin cover 42 is not particularly limited, but examples thereof include polypropylene.

[0025] In this embodiment, the housing 40 has a box-like shape that is long in one direction to match the shape of the front bumper 101, but the shape of the housing 40 is not particularly limited to this. The shape of the housing 40 may be appropriately set depending on the installation position of the in-vehicle antenna device 1 in the vehicle 100 and the arrangement of the antenna board 20. The housing 40 includes an antenna accommodating section 43 that accommodates the antenna board 20 and two slack storage sections 44 that accommodate slack sections 11 (described below) of the optical fiber 10. The two slack storage sections 44 are provided at two longitudinal ends of the housing 40, respectively. Note that the locations of the slack storage sections 44 are not particularly limited to this. For example, in FIG. 3 , a plate-like member that divides the space within the housing 40 into upper and lower sections may be provided on the main body 41, with the upper space being the antenna accommodating section 43 and the lower space being the slack storage section 44.

[0026] A flexible printed wiring board 30 is provided in the antenna accommodating portion 43 of the housing 40. Although not particularly limited, the flexible printed wiring board 30 is fixed to the bottom surface of the housing 40 with double-sided tape. The flexible printed wiring board 30 is electrically connected to a power source 3 provided in the vehicle, and is also electrically connected to each antenna board 20 via a flat cable (not shown). Electrical energy is supplied from the power source 3 to each antenna board 20 via the flexible printed wiring board 30.

[0027] The antenna substrate 20 is a printed wiring board including a substrate 21, an antenna element 22, and an optical-electrical conversion circuit 23. As shown in FIG. 3 , the substrate 21 is connected to a plurality of connection pins 24 that penetrate the flexible printed wiring board 30 on the bottom surface of the housing 40. This holds the antenna substrate 20 within the housing 40. The antenna element 22 and the optical-electrical conversion circuit 23 are provided on the substrate 21. The optical-electrical conversion circuit 23 is electrically connected to the antenna element 22 via an electrical circuit and optically connected to the optical fiber 10. The antenna element 22 may be, but is not limited to, a patch antenna or the like. The optical-electrical conversion circuit 23 may be, but is not limited to, a silicon photonics chip or the like. The antenna substrate 20 includes a radio wave transmitting (Tx) antenna substrate 20A and a radio wave receiving (Rx) antenna substrate 20B (see FIG. 4 ). Hereinafter, the radio wave transmitting antenna substrate 20A and the radio wave receiving antenna substrate 20B will be collectively referred to as the antenna substrate 20.

[0028] The multiple antenna boards 20 are arranged at intervals within the housing 40 in a straight line along the longitudinal direction of the housing 40. The antenna boards 20 may be arranged according to the performance required of the in-vehicle antenna device 1, and the arrangement method is not particularly limited. For example, the antenna boards 20 may be arranged at equal intervals or at unequal intervals. Furthermore, although the antenna boards 20 are arranged in a single row along the longitudinal direction in this embodiment, they may also be arranged in two or more rows.

[0029] Furthermore, if the vehicle 100 is equipped with a plurality of in-vehicle antenna devices 1, the antenna substrates 20 may be arranged so that an antenna array is formed by the antenna substrates 20 included in each of the in-vehicle antenna devices 1. For example, although not shown, if the vehicle 100 is equipped with an in-vehicle antenna device 1 aligned in a direction horizontal to the front bumper 101 and an in-vehicle antenna device 1 aligned in a direction perpendicular to the front bumper 101, the antenna substrates 20 included in each of the in-vehicle antenna devices 1 may be arranged so as to form a so-called sparse array.

[0030] The optical fibers 10 are pulled from the outside to the inside of the housing 40 as an optical fiber cord 60 covered with a sheath via aramid fibers. One end of the optical fiber cord 60 is provided with a branching section 61 that exposes the optical fibers 10 from the sheath and splits them into individual optical fibers 10. Each optical fiber 10 split at the branching section 61 is connected to the photoelectric conversion circuit 23 of the antenna substrate 20.

[0031] The optical connector 50 is provided at the other end of the optical fiber cord 60 opposite to the branching portion 61. The optical connector 50 is also connected to an optical connector 50' provided on another optical fiber cord 60' inside the vehicle 100. The optical fiber cord 60' is connected to an ECU (Electronic Control Unit) 2 inside the vehicle 100. Therefore, each antenna board 20 of the in-vehicle antenna device 1 is optically connected to the ECU 2 inside the vehicle 100.

[0032] In this embodiment, two optical fiber cords 60 are provided, but there is no particular limitation on the number of optical fiber cords 60. In addition, in this embodiment, one optical fiber cord 60 is provided between the branching portion 61 and the optical connector 50, but a plurality of optical fiber cords 60 connected to each other via optical connectors may be provided between the branching portion 61 and the optical connector 50. Furthermore, there is no particular limitation on the number of optical fibers 10 provided in the in-vehicle antenna device 1.

[0033] The number of optical fibers 10 connected to one antenna substrate 20 may be one or two or more. Although not particularly limited, when two or more optical fibers 10 are connected to the antenna substrate 20, it is preferable that the optical fibers 10 connected to one antenna substrate 20 are linked to each other.

[0034] The optical fiber 10 has excess portions 11 and 12. The excess portions 11 and 12 are portions where two or more different points on the optical fiber 10 are arranged to overlap each other, and in this embodiment, as shown in Fig. 2, are portions where the optical fiber 10 is wound.

[0035] The excess length portion 11 is provided between the branching portion 61 and the antenna substrate 20, and is stored in the excess length storage portion 44 of the housing 40. In addition, the excess length portion 11 of each optical fiber 10 is arranged in a stacked manner in the excess length storage portion 44, as shown in FIG.

[0036] The slack portion 12 is disposed outside the housing 40. The slack portion 12 is formed by removing a portion of the sheath of the optical fiber cord 60, drawing out a portion of the optical fiber 10 to the outside of the optical fiber cord 60, and winding up the drawn optical fiber 10. The slack portion 12 is stored inside a junction box (not shown) in the vehicle 100, although this is not particularly limited. Note that the optical fiber 10 does not necessarily have to have the slack portion 12 disposed outside the housing 40.

[0037] The optical fibers 10 are all equal in length. In this embodiment, the lengths of the optical fibers 10 from one end connected to the antenna substrate 20 to the other end connected to the optical connector 50 are all equal. The length of each optical fiber 10 is set to match the longest optical fiber 10, i.e., the optical fiber 10 with the longest wiring length required from the antenna substrate 20 to the optical connector 50. Therefore, the optical fiber 10 with a relatively short wiring length required from the antenna substrate 20 to the optical connector 50 has an excess portion. The excess portions 11 and 12 in this embodiment are formed by wrapping and bundling the excess portions of each optical fiber 10, and are provided to make the lengths of the optical fibers 10 equal. By making the lengths of the optical fibers 10 equal, it is possible to suppress phase shifts caused by differences in the lengths of the optical fibers 10, thereby improving the detection accuracy of the in-vehicle antenna device 1.

[0038] In this embodiment, the excess length portion 11 is simply disposed in the excess length storage portion 44 (bottom surface) of the housing 40, but the method of storing the excess length portion 11 is not particularly limited to this. For example, a hook protruding from the bottom surface or wall surface of the excess length storage portion 44 may be provided, and the excess length portion 11 may be stored by hooking a part of the excess length portion 11 onto the hook. Alternatively, buffer material may be disposed to surround the excess length portion 11, and the excess length portion 11 may be stored in the space between the buffer material. This prevents the excess length portion 11 from moving due to vibrations while the vehicle 100 is running and coming into contact with the antenna substrate 20 or the like, causing breakage of the optical fiber 10.

[0039] FIG. 4 is a configuration diagram of an obstacle detection system 1000 according to this embodiment. As shown in FIG. 4 , the obstacle detection system 1000 according to this embodiment includes an ECU 2 and an in-vehicle antenna device 1. An optical signal generated by a signal generator 201 in the ECU 2 and subjected to electro-optical conversion is transmitted to the radio wave transmitting antenna board 20A via an optical connector 50 and an optical fiber 10. This optical signal is converted into an electrical signal by an optical-electrical conversion circuit 23 and transmitted to an antenna element 22, which then transmits radio waves. Next, radio waves reflected by a detection target, such as an obstacle, are received by the antenna element 22 of the radio wave receiving antenna board 20B. The electrical signal transmitted from the antenna element 22 is converted into an optical signal by the optical-electrical conversion circuit 23 and transmitted to the ECU 2 via the optical fiber 10. The ECU 2 converts the optical signal into an electrical signal, and the electrical signal is analyzed by a computer 202 to calculate the distance to the target, the speed of the target, the angle of the target, and the like.

[0040] In this embodiment, the optical fiber 10 includes slack portions 11 and 12. During manufacturing of the vehicle-mounted antenna device 1, the optical fiber 10 is easily handled because it includes the slack portions 11 and 12. This reduces the likelihood of mistakes, such as accidentally bending the optical fiber 10, and prevents breakage of the optical fiber 10. Furthermore, if the slack portions 11 and 12 were not provided, the optical fiber 10 would need to be positioned near the antenna substrate 20 or the like to accommodate the slack portion of the optical fiber 10 resulting from equalizing the lengths of the optical fibers 10. Therefore, if the slack portions 11 and 12 were not provided, the optical fiber 10 would likely come into contact with surrounding structures. On the other hand, in this embodiment, the optical fiber 10 includes the slack portions 11 and 12, and the slack portions of the optical fiber 10 are bundled together, thereby preventing the optical fiber 10 from coming into contact with surrounding structures. This prevents breakage of the optical fiber 10 due to vibrations during vehicle 100 travel.

[0041] Furthermore, in this embodiment, the excess length 11 of each optical fiber 10 is arranged in a stacked manner in the excess length storage section 44 of the housing 40. That is, the excess length 11 of the multiple optical fibers 10 is arranged in a stacked manner in predetermined positions. This makes it possible to reduce the space required to store the optical fibers 10 inside the in-vehicle antenna device 1, and to prevent the optical fibers 10 from coming into contact with surrounding structures. This further reduces the occurrence of breakage of the optical fibers 10.

[0042] It should be noted that the above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0043] DESCRIPTION OF SYMBOLS 1...In-vehicle antenna device 10...Optical fiber 11, 12...Excess length portion 20...Antenna board 21...Board 22...Antenna element 23...Opto-electrical conversion circuit 24...Connection pin 30...Printed wiring board 40...Housing 41...Main body 42...Resin cover 50, 50'...Optical connector 60, 60'...Optical fiber cord 61...Branch portion 2...ECU 201...Signal generator 202...Computer 3...Power supply 100...Vehicle 101...Front bumper 1000...Optical object detection system

Claims

1. An in-vehicle antenna device comprising: a plurality of antenna substrates; and a plurality of optical fibers connected to the plurality of antenna substrates, each of the optical fibers having an excess length including a portion of the optical fiber that is arranged so that two or more different points on the optical fiber overlap each other.

2. An on-vehicle antenna device according to claim 1, wherein the excess length portion is a portion provided to make the lengths of the plurality of optical fibers equal to each other.

3. An in-vehicle antenna device according to claim 1 or 2, wherein the excess length portion includes a wound portion of the optical fiber.

4. An in-vehicle antenna device according to any one of claims 1 to 3, wherein the excess length portions are arranged in a stacked manner at predetermined positions on the in-vehicle antenna device.

5. An in-vehicle antenna device according to any one of claims 1 to 4, comprising a housing that accommodates the antenna substrate and the optical fiber, the excess length portion including a first excess length portion that is accommodated in the housing, and the housing comprising an antenna accommodating section that accommodates the antenna substrate, and an excess length storage section that stores the first excess length portion.

6. An in-vehicle antenna device according to claim 5, wherein the slack storage section is provided at an end of the housing along the longitudinal direction.

7. An in-vehicle antenna device according to claim 5 or 6, wherein the excess length portion includes a second excess length portion disposed outside the housing.

8. An in-vehicle antenna device according to any one of claims 5 to 7, comprising a flexible printed wiring board electrically connected to the antenna substrate and housed in the housing.

9. An in-vehicle antenna device according to any one of claims 1 to 8, wherein the antenna substrate comprises: an antenna element; and an optical-electrical conversion circuit electrically connected to the antenna element and optically connected to the optical fiber.

10. An in-vehicle antenna device according to any one of claims 1 to 9, wherein the plurality of antenna substrates are arranged at intervals.

11. An in-vehicle antenna device according to any one of claims 1 to 10, comprising an optical connector provided at the end of the optical fiber opposite to the end connected to the antenna board, and the lengths of each of the optical fibers from the antenna board to the optical connector are equal to each other.

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