Antenna device and door mirror device

Abstract

To suppress deterioration in antenna characteristics of an antenna device.SOLUTION: An antenna device 10 is housed in a door mirror device 1 including a mirror opening / closing shaft part 6 in which cables 7a, 7b of electronic components are wired on a predetermined + x direction side. An antenna device 10 includes an antenna element and an attachment part. The mounting unit mounts the antenna device 110 at a position on the side (- x direction side) opposite to the routing positions of the cables 7a and 7b in the door mirror device 1 with respect to the mirror opening and closing shaft 6.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an antenna device and a door mirror device. [Background technology]

[0002] Conventionally, antenna devices built into vehicle door mirror devices have been known. For example, a vehicle antenna is known in which an antenna element connected to a coaxial cable is attached to the inside of an enclosure serving as an outer cover of the door mirror (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-42977 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional vehicle antennas do not take into consideration the influence of cables for electronic components other than the antenna element. The other components are the defogger and the blind spot light-emitting unit (indicator). The defogger is equipped with a heating wire that heats the door mirror to remove condensation and ice. The heating wire performs this heating. The blind spot is equipped with a light-emitting unit that detects vehicles in the blind spot of the door mirror and notifies the driver by emitting light from the back of the door mirror. The light-emitting unit performs this light emission. The door mirror device houses the cables connected to the defogger and light-emitting unit.

[0005] The defogger and blind spot lights carry drive signals, which affect the vehicle antenna's performance. If the cables are too close to the vehicle antenna, the antenna performance may be degraded.

[0006] An object of the present invention is to suppress deterioration of the antenna characteristics of an antenna device. [Means for solving the problem]

[0007] In order to solve the above problems, the antenna device of the present invention comprises: An antenna device housed in a door mirror device having a mirror opening / closing shaft part in which a cable of an electronic component is routed in a predetermined direction, The antenna device includes: an antenna element; and a mounting portion for mounting the antenna element at a position on the opposite side of the mirror opening / closing shaft portion from the position where the cable is routed in the door mirror device. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress deterioration of the antenna characteristics of the antenna device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an external perspective view showing a door mirror device equipped with an antenna device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing the internal configuration of the door mirror device. [Figure 3] 3 is a perspective view showing the internal configuration of the door mirror device of FIG. 2 from another viewpoint. [Figure 4] FIG. 2 is a perspective view showing an antenna device. [Figure 5] FIG. 2 is a top view showing the film antenna and the cable. [Figure 6] FIG. 10 is a diagram showing an antenna device and a cable spaced 50 mm apart. [Figure 7] 10 is a diagram showing the frequency characteristics of the VSWR of the antenna device when the distance from the cable is changed. FIG. [Figure 8] FIG. 10 is a diagram showing the frequency characteristics of the average gain of the antenna device in the door mirror device of the example and the comparative example. [Figure 9]FIG. 10 is a diagram showing the frequency characteristics of the VSWR of the antenna devices in the door mirror devices of the example and the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the scope of the present invention is not limited to the illustrated examples.

[0011] An embodiment of the present invention will be described with reference to Figs. 1 to 9. First, the device configuration of this embodiment will be described with reference to Figs. 1 to 5. Fig. 1 is an external perspective view showing a door mirror device 1 of this embodiment. Fig. 2 is a perspective view showing the internal configuration of the door mirror device 1. Fig. 3 is a perspective view showing the internal configuration of the door mirror device 1 from a different perspective than Fig. 2. Fig. 4 is a perspective view showing an antenna device 10. Fig. 5 is a top view showing a film antenna 100 and a cable 310.

[0012] As shown in FIG. 1, a door mirror device 1 is installed on the front door of a vehicle such as an automobile. The door mirror device 1 includes a mirror 2a, a turn signal light 2b, a cable 2c, and outer covers 3a and 3b. The mirror 2a is a rearview mirror for the vehicle, and the angle of the mirror surface can be adjusted using a motor (not shown). The turn signal light 2b is a turn signal light. One end of the cable 2c is connected to an antenna and electronic components inside the door mirror device 1, and the other end is connected to a communication unit such as a telematics control unit (TCU) and an electronic control unit (ECU) inside the vehicle. The ECU is a unit that controls a system consisting of electronic components in the vehicle using electronic circuits. The door mirror device 1 houses electronic components such as a defogger, a blind spot light (all not shown), and a mirror opening / closing axis 6 (FIG. 2), which will be described later. The defogger is an electric heating wire located on the back side of the mirror 2a. The light emitting portion of the blind spot is, for example, an LED (Light Emitting Diode) arranged on the back side of the mirror 2a.

[0013] The outer covers 3a and 3b are covers provided on the outside of the door mirror device 1 and are made of, for example, radio wave permeable resin. The outer cover 3a is an outer cover provided on the upper (zenith direction) side. The outer cover 3b is an outer cover provided on the lower (nadir (ground) direction) side.

[0014] The antenna device 10 (FIG. 2) of this embodiment is installed inside the door mirror device 1. Specifically, the antenna device 10 is provided inside the outer covers 3a and 3b. Therefore, the vehicle user cannot see the antenna device 10 from the outside. The antenna device 10 is, for example, an antenna device for cellular communication as a wireless communication method. The cellular communication is assumed to be communication in the frequency bands of 3G (Generation), 4G, and 5G (including Sub6). The frequency band for cellular communication is approximately 617 [MHz] to 6 [GHz].

[0015] 2 and 3 show the internal configuration of the door mirror device 1 with the outer cover 3a removed. As shown in Fig. 2 and 3, the door mirror device 1 further includes inner covers 2a1 and 2a4, antennas 5a, 5b and 5c, a mirror opening / closing shaft 6, cables 7a and 7b, and an antenna device 10.

[0016] The inner cover 2a1 is a cover made of resin or the like provided on the inside of the mirror 2a. The inner cover 4 is a cover made of resin or the like provided further inside the outer covers 3a and 3b. The inner cover 4 houses components such as an actuator such as a motor, a blind spot light emitter, and cables (all not shown). The inner cover 2a1 is provided on the inside with connectors for cables 7a and 7b, a defogger, etc.

[0017] Antenna 5a is an antenna for transmitting and receiving radio waves of Wi-Fi (registered trademark) and is disposed on inner cover 2a1 on the inside of mirror 2a. Antenna 5b is an antenna for transmitting and receiving radio waves of Bluetooth (registered trademark) and is disposed on inner cover 4. Antenna 5c is a patch antenna for receiving radio waves of GNSS (Global Navigation Satellite System) and is disposed on bracket 200, which will be described later.

[0018] The antenna device 10 is attached to the inner cover 4 by screws 4a provided on the inner cover 4. More precisely, the antenna device 10 is attached to the inner cover 2a1 by fastening together the screws 4a for attaching the inner cover 4 to the inner cover 2a1. In this way, the antenna device 10 is provided between the outer covers 3a, 3b and the inner cover 4. However, the method of attaching the antenna device 10 to the inner cover 2a1 is not limited to fastening together with the screws 4a.

[0019] The mirror opening / closing shaft 6 is a component that rotates the door mirror device 1 from the vehicle door to an open state (where the mirror 2a is visible) or a closed state (where the mirror 2a is hidden). The mirror opening / closing shaft 6 is made of a motor that is made of a substantial metal. The mirror opening / closing shaft 6 is connected to the ECU via a cable 2c. The mirror opening / closing shaft 6 is driven and controlled by the ECU.

[0020] One end of cable 7a is electrically connected to the blind spot light-emitting unit, and the other end is electrically connected to the ECU via cable 2c. Cable 7a has a connector 7a1 at the end of the blind spot light-emitting unit. Cable 7a is made of, for example, an AVSS line (an ultra-thin constant voltage line for automobiles). The light-emitting unit is driven and controlled by the ECU.

[0021] One end of cable 7b is electrically connected to the defogger, and the other end is electrically connected to the ECU via cable 2c. Cable 7b has a connector 7b1 at the end of the cable. Cable 7b is made of, for example, an AVSS line. The defogger is controlled by the ECU.

[0022] As shown in FIG. 2 , the x-axis is taken to be approximately the longitudinal direction of the door mirror device 1. The y-axis is taken to be approximately the lateral direction of the door mirror device 1, perpendicular to the x-axis. Cable 7a is drawn into the nadir side of the mirror opening / closing axis 6 as part of cable 2c and exposed from the zenith side of the mirror opening / closing axis 6. The exposed cable 7a is routed outside (+x side) of the mirror opening / closing axis 6, and a connector 7a1 is connected to the end of cable 7a. Similarly, cable 7b is drawn into the nadir side of the mirror opening / closing axis 6 as part of cable 2c and exposed from the zenith side of the mirror opening / closing axis 6. The exposed cable 7b is routed outside (+x side) of the mirror opening / closing axis 6, and a connector 7b1 is connected to the end of cable 7b. The antenna device 10 is disposed on the near side (-y side) and inside (-x side) of the mirror opening / closing axis 6. The connection destinations of the cables 7a and 7b are arranged on the far side (+y direction side) of the antenna device 10.

[0023] 4, the antenna device 10 includes a film antenna 100, a bracket 200, a cable 310, and a cable cover 320. The film antenna 100 is a planar antenna main body of the antenna device 10. The bracket 200 fixes and supports the film antenna 100 at a predetermined bending angle (degree of bending) that is formed in advance.

[0024] The cable 310 is a coaxial cable, one end of which is electrically connected to the film antenna 100, and the other end of which is electrically connected via a cable 2c to a communication unit provided inside the vehicle. The cable cover 320 is a cover made of resin or the like and has a substantially rectangular parallelepiped shape, and covers the tip of the cable 310 connected to the film antenna 100. The cable cover 320 is positioned by its protrusion (not shown) penetrating a hole H0 in the film antenna 100. The cable cover 320 is screwed into a hole H1 in the film antenna 100 to sandwich and protect the film antenna 100 and the cable 310 from both sides.

[0025] 5 shows the film antenna 100 and the cable 310 in the antenna device 10 after being removed from the bracket 200 to form a flat surface and after the cable cover 320 has been removed. The film antenna 100 has an antenna element 110, a film 120, and a resistor R1. The antenna element 110 has a radiating element 111 and a GND (Ground) element 112.

[0026] The antenna element 110 is a planar dipole antenna made of metal such as copper foil, but the antenna element 110 is not limited to a dipole antenna.

[0027] The radiating element 111 is an antenna element that receives radio waves and passes an antenna current. The GND element 112 is an antenna element that is grounded. The film 120 is a single film made of an insulating (dielectric) resin such as polyimide, and is laminated (laminated) on the back surface of the antenna element 110 to cover the antenna element 110 from below. The film 120 holds (supports) and protects the antenna element 110. The film antenna 100 is bendable. Furthermore, the antenna element 110 and the film 120 have a resist (not shown) formed on the upper layer (surface) thereof.

[0028] The radiating element 111 has a feed point P1 provided near the gap between it and the GND element 112. The inner conductor of the cable 310 is electrically connected to the feed point P1 by soldering or the like. The outer conductor of the cable 310 is electrically connected to the GND element 112 by soldering or the like. The resistor R1 is electrically connected to the radiating element 111 and the GND element 112 via a wiring section. The resistor R1 is a detection resistor for detecting whether or not the antenna device 10 is electrically connected to a communication unit.

[0029] As shown in FIG. 4, the bracket 200 is a molded product made of a single piece of resin, such as ABS (Acrylonitrile Butadiene Styrene) resin, as a dielectric. The bracket 200 has a bracket main body 210, a notch portion 220, an attachment portion 230, a base portion 240, and a C-shaped portion 250. The bracket main body 210 is a flat plate of the main body of the bracket 200. The bracket main body 210 has a relatively small predetermined bending angle. Therefore, the bending angle of the film antenna 100 attached to the bracket 200 is fixed by the bending angle of the bracket 200. However, the bending angle of the bracket 200 is not limited to the bending angle shown in FIG. 4.

[0030] The cutout portion 220 is a rectangular cutout portion in the bracket main body 210. A cable cover 320 that stores the tip portion of the cable 310 is inserted into the cutout portion 220. The film antenna 100 is attached to the bracket 200 by, for example, being attached to the bracket main body 210 with double-sided tape.

[0031] The bracket body 210 (bracket 200) as a dielectric has a wavelength shortening effect according to its dielectric constant. Therefore, by increasing the dielectric constant of the bracket 200, the length of the antenna element 110 of the attached film antenna 100 can be shortened. Based on a rough estimate from the frequency fluctuation measured in the ABS resin bracket 200, the antenna element 110 can be reduced in size by about 10%.

[0032] The mounting portion 230 extends to the upper left side of the bracket main body 210 in the figure, and has a hole through which the screw 4a is inserted. The mounting portion 230 is a portion that mounts the bracket 200 to the inner cover 2a1 by threading the screw 4a through the hole. The base portion 240 extends from the back side of the bracket main body 210 to the left in the figure, and is a base portion on which the antenna 5c is installed. The C-shaped portion 250 is a C-shaped recess that extends from the back side of the bracket main body 210 downward in the figure. The C-shaped portion 250 is fitted into a protrusion (not shown) of the outer cover 3b.

[0033] The bracket 200 is firmly attached to the inner cover 2a1 and the outer cover 3b by the screw 4a of the attachment portion 230 being threadedly engaged and the C-shaped portion 250 being fitted thereto.

[0034] Next, the distance between the antenna device 10 and the cables 7a, 7b that affects the antenna characteristics will be described with reference to Figures 6 and 7. Figure 6 is a diagram showing the antenna device 10 and the cables 7a2, 7b2 when the distance is 50 mm. Figure 7 is a diagram showing the frequency characteristics of the VSWR (Voltage Standing Wave Ratio) of the antenna device 10 when the distance from the cables 7a2, 7b2 is changed.

[0035] The distance D between the antenna device 10 and the simulated cables 7a2 and 7b2 of the cables 7a and 7b was changed, and the VSWR versus frequency [GHz] was measured as the antenna characteristic of the antenna device 10. Specifically, the VSWR of the antenna device 10 alone (standalone) and the VSWR of configurations in which the distance D between the antenna device 10 and the cables 7a2 and 7b2 was changed to 0, 30, 50, and 60 [mm] were measured.

[0036] For example, as shown in FIG. 6, the antenna device 10 is placed with the surface facing the film antenna 100 facing downward, and a sponge-like urethane 8 is placed on the back surface of the antenna device 10. Furthermore, cables 7a2 and 7b2 are placed on top of the urethane 8. The distance D can be changed by changing the height of the urethane 8. For example, the distance D in FIG. 6 is 50 mm. If the urethane 8 and cables 7a2 and 7b2 are not present, the distance D is 0 mm. If the urethane 8 and cables 7a2 and 7b2 are not present, the antenna device 10 will be a standalone product.

[0037] Figure 7 shows the measurement results, with the VSWR of antenna device 10 alone (vertical axis) and the VSWR of antenna device 10 when the distance D is changed to 0, 30, 50, and 60 [mm] against the frequency [GHz] (horizontal axis). Furthermore, Figure 7 shows multiple frequency bands for cellular communications with dotted lines. The lower the VSWR value, the better the resonance and the better the characteristics.

[0038] Measurement results showed that antenna device 10 exhibited generally favorable VSWR characteristics when distance D was approximately 50 mm or greater. Here, at the lowest frequency of 617 MHz in the cellular communication frequency band, the wavelength λ of the radio wave is approximately 486.2 mm. Therefore, when cables 7a2 and 7b2 are routed at a position at least a predetermined distance D1 (=λ / 10 mm) away from antenna device 10, favorable antenna characteristics are obtained.

[0039] Next, the antenna characteristics of the door mirror devices 1 of the example and the comparative example will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a diagram showing the frequency characteristics of the average gain of the antenna device 10 in the door mirror devices 1 of the example and the comparative example. Fig. 9 is a diagram showing the frequency characteristics of the VSWR of the antenna device 10 in the door mirror devices 1 of the example and the comparative example.

[0040] An example and a comparative example of the door mirror device 1 were prepared, and the gain and VSWR as antenna characteristics of these antenna devices 10 were measured. The door mirror device 1 of the example is configured such that the cables 7a and 7b are routed outside (on the +x direction side of) the mirror opening / closing axis 6 relative to the antenna device 10. In other words, the antenna device 10 is disposed on the opposite side of the mirror opening / closing axis 6 from the routing position of the cables 7a and 7b. The door mirror device 1 of the example is configured such that the antenna device 10 and the cables 7a and 7b are spaced apart by a predetermined distance D1 or more.

[0041] The door mirror device 1 of the comparative example is configured such that the cables 7a and 7b are routed inside (on the -x direction side of) the mirror opening / closing shaft 6 relative to the antenna device 10. In other words, the antenna device 10 is disposed on the same side as the routing positions of the cables 7a and 7b, with the mirror opening / closing shaft 6 as the center. The door mirror device 1 of the comparative example is configured such that the antenna device 10 and the cables 7a and 7b are spaced apart by less than a predetermined distance D1.

[0042] FIG. 8 shows the measurement results, plotting the average gain [dBi] of the antenna device 10 in the door mirror devices 1 of the example and the comparative example on the vertical axis against the frequency on the horizontal axis. The average gain [dBi] is the average value of the gain [dBi] of the antenna device 10 at elevation angles of 0 to 30° (0°, 10°, 20°, 30°). The elevation angle is the elevation angle when the lateral direction (horizontal direction) when the antenna device 10 (bracket 200) is upright is set to 0°. The gain [dBi] at each elevation angle is the average value of the gain around 360° on a lateral (horizontal) plane centered on the antenna device 10.

[0043] The higher the average gain [dBi], the better the characteristics. The door mirror device 1 of the example has better average gain characteristics of the antenna device 10 than the door mirror device 1 of the comparative example.

[0044] 9 shows the measurement results, with the VSWR of the antenna device 10 in the door mirror device 1 of the embodiment and the comparative example shown on the vertical axis against the frequency on the horizontal axis. The door mirror device 1 of the embodiment has better VSWR characteristics for the antenna device 10 than the door mirror device 1 of the comparative example.

[0045] As described above, according to the present embodiment, the antenna device 10 is housed in a door mirror device 1 that includes a mirror opening / closing shaft 6 on which the cables 7a and 7b of electronic components are routed in a predetermined +x direction. The antenna device 10 includes an antenna element 110, an attachment portion 230, and a C-shaped portion 250. The attachment portion 230 and the C-shaped portion 250 attach the antenna element 110 to a position on the opposite side (-x side) from the routing position of the cables 7a and 7b in the door mirror device 1, with the mirror opening / closing shaft 6 as the center. The door mirror device 1 includes the mirror opening / closing shaft 6, electronic components, and the cables 7a and 7b of the electronic components. Therefore, the mirror opening / closing shaft 6 increases the distance between the cables 7a and 7b and the antenna device 10, thereby suppressing degradation of the antenna characteristics of the antenna device 10 due to the cables 7a and 7b.

[0046] The electronic components are the defogger of the mirror 2a of the door mirror device 1 and the light emitting portion of the blind spot of the door mirror device 1. This makes it possible to suppress deterioration of the antenna characteristics of the antenna device due to the defogger and blind spot cables 7a, 7b.

[0047] The distance between the cables 7a, 7b and the antenna device 10 is equal to or greater than a predetermined distance that is one-tenth the wavelength λ of the radio wave corresponding to the antenna element 110. Therefore, the predetermined distance from the mirror opening / closing axis 6 can further suppress deterioration of the antenna characteristics of the antenna device 10 caused by the cables 7a, 7b.

[0048] The above-described embodiment is merely an example of the antenna device and door mirror device according to the present invention, and the present invention is not limited to this.

[0049] For example, in the above embodiment, the frequency band of the wireless communication method of the antenna device 10 is the frequency band of cellular communication, but this is not limited to this. The frequency band of the wireless communication method of the antenna device 10 may be the frequency band of another wireless communication method.

[0050] In the above embodiment, the electronic components included in the door mirror device 1 are the light-emitting units for the defogger and blind spot, and the cables 7a and 7b are the cables for the defogger and blind spot, but this is not limited to this. The electronic components included in the door mirror device 1 may be configured to be at least one of a camera and an actuator. The camera is, for example, an around-view camera provided in the door mirror device 1. The actuator is, for example, an actuator (motor) for changing the tilt of the mirror 2a. This configuration can suppress deterioration of the antenna characteristics of the antenna device due to at least one of the camera and actuator cables.

[0051] In addition, the detailed configurations and operations of the antenna device 10 and the door mirror device 1 in the above embodiment can also be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0052] 1 Door mirror device 2a Mirror 2b Turn Light 2c,310,7a,7b,7a2,7b2 cable 3a, 3b Outer cover 2a1,4 Inner cover 4a Screw 5a, 5b, 5c antennas 6 Mirror opening and closing axis 7a1,7b1 connector 10 Antenna device 100 Film Antenna 110 antenna element 111 Radiating element 112 GND element R1 Resistor H0,H1 Hole P1 feeding point 200 bracket 210 Bracket body 220 Notch 230 Mounting part 240 Base 250 C-shaped part 320 Cable Cover

Claims

1. An antenna device housed in a door mirror device having a mirror opening / closing shaft part in which a cable of an electronic component is routed in a predetermined direction, The antenna device includes: an antenna element; an attachment portion for attaching the antenna element to a position on the opposite side of the mirror opening / closing axis from the position where the cable is routed in the door mirror device;

2. 2. The antenna device according to claim 1, wherein the electronic component is at least one of a defogger of the door mirror device and a light emitting portion of a blind spot of the door mirror device.

3. The antenna device according to claim 1 , wherein the electronic component is at least one of a camera and an actuator of the door mirror device.

4. 2. The antenna device according to claim 1, wherein the distance between the cable and the antenna device is equal to or greater than a predetermined distance that is one-tenth the wavelength of the radio wave corresponding to the antenna element.

5. An antenna device according to any one of claims 1 to 4; the mirror opening / closing shaft; A door mirror device comprising the electronic component and a cable for the electronic component.

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