Patent Publication Number: US-2023163451-A1

Title: Attachment structure for antenna device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of International Patent Application No. PCT/JP2021/024023 filed on Jun. 24, 2021, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2020-129594 filed on Jul. 30, 2020. The entire disclosure of all of the above applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to an attachment structure for an antenna device attached to a vehicle. 
     BACKGROUND 
     An antenna device with a shark fin shape arranged on a roof of a vehicle. 
     SUMMARY 
     According to at least one embodiment, an attachment structure for an antenna device includes the antenna device attached to a vehicle. The antenna device includes an antenna element and a wire. The antenna element is arranged on a roof of the vehicle, and performs one or both of transmission and reception of a radio wave. The wire electrically connects the antenna element and a power supply unit provided inside the vehicle, and extends through a waterproof structure located between the roof and a member provided at a peripheral edge of the roof. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. 
         FIG.  1    is a front view of an antenna device according to a first embodiment. 
         FIG.  2    is a cross-sectional view illustrating the antenna device. 
         FIG.  3    is a diagram illustrating an attachment structure for the antenna device. 
         FIG.  4    is a diagram illustrating an attachment state of the antenna device. 
         FIG.  5    is a diagram illustrating the attachment state of the antenna device. 
         FIG.  6    is a cross-sectional view illustrating a sealing structure. 
         FIG.  7    is a cross-sectional view illustrating an attachment structure for an antenna device according to a second embodiment. 
         FIG.  8    is a cross-sectional view illustrating the antenna device. 
     
    
    
     DETAILED DESCRIPTION 
     To begin with, examples of relevant techniques will be described. According to a comparative example, an antenna device with a shark fin shape arranged on a roof of a vehicle. In this antenna device, a circuit board of the antenna device arranged on the roof is electrically connected to an in-vehicle electronic device such as a communication device provided inside the vehicle via a signal cable extending through an opening provided on the roof. 
     Since the antenna device is provided on the roof, the opening is provided on the roof. Thus, a waterproof structure is required for the opening. Providing the opening on the roof can adversely affect rigidity of a vehicle body depending on a position and size of the opening, and thus, the opening may not be formed. 
     In contrast to the comparative example, according to an attachment structure for an antenna device of the present disclosure, the antenna device can be attached to a roof without providing an opening on the roof. 
     According to one aspect of the present disclosure, an attachment structure for an antenna device includes the antenna device attached to a vehicle. The antenna device includes an antenna element and a wire. The antenna element is arranged on a roof of the vehicle, and performs one or both of transmission and reception of a radio wave. The wire electrically connects the antenna element and a power supply unit provided inside the vehicle, and extends through a waterproof structure located between the roof and a member provided at a peripheral edge of the roof. 
     According to the attachment structure for the antenna device, the antenna element is arranged on the roof of the vehicle, and the wire electrically connects the antenna element and the power supply unit provided inside the vehicle. The wire extends through the waterproof structure located between the roof and the member provided at a peripheral edge of the roof. The member provided at the peripheral edge of the roof is, for example, a window, a spoiler, or a molded resin, and constitutes the vehicle. A waterproof structure ensures a waterproof property at a gap between the peripheral edge of the roof and the member. The waterproof property can be ensured by the waterproof structure through which the wire extends. As a result, the wire can be drawn into an interior of the vehicle from an upper side of the roof without an opening being formed on the roof for the wire. Therefore, the antenna element of the antenna device can be attached to the roof without providing an opening in the roof. 
     The following describes embodiments for carrying out the present disclosure with reference to the drawings. In each embodiment, a part corresponding to the part described in the preceding embodiment may be denoted by the same reference numeral or a reference numeral with one character added to a preceding reference numeral; thereby, redundant explanation may be omitted. In each embodiment, when only part of the configuration is described, the other part of the configuration can be the same as that in a preceding embodiment. The present disclosure is not limited to combinations of embodiments which combine parts that are explicitly described as being combinable. As long as no problems are present, the various embodiments may be partially combined with each other even if not explicitly described. 
     First Embodiment 
     Hereinafter, a first embodiment of the present disclosure will be described with reference to  FIGS.  1  to  6   . An antenna device  10  has a substantially L-shape in a plan view as shown in  FIG.  1   . The antenna device  10  is arranged on a roof  101  of a vehicle  100  as shown in  FIGS.  3  to  6   . The roof  101  forms a ceiling of the vehicle  100 , and is made of a flat metal plate in the present embodiment. In the present embodiment, the antenna device  10  has a thin film structure or a film structure and has electrical characteristics and flexibility, and is called a film antenna. 
     As shown in  FIG.  3   , a vehicle body frame  102  is provided under the roof  101  of the vehicle  100 , that is, between the roof  101  and a vehicle compartment. The vehicle body frame  102  is a member that reinforces the roof  101 . The vehicle body frame  102  also is a member that forms an outer frame of the vehicle  100  together with the roof  101 . The vehicle body frame  102  is fixed to the roof  101  by mechanical connection, such as welding. A roof lining  103  that constitutes a ceiling of the vehicle compartment is provided under the vehicle body frame  102 . There is a gap between the roof  101  and the roof lining  103 . 
     The antenna device  10  includes an antenna element  11 , a magnetic member  12 , a base film  13 , a decorative printed layer  14  and a topcoat layer  15 . The antenna device  10  has a structure in which the antenna element  11  having a foil-like shape is provided on the base film  13  having a thin film shape. 
     The base film  13  has the thin film shape and an insulating property. The decorative printed layer  14  is provided on a surface of the base film  13  facing away from the vehicle  100 , that is, facing upward in  FIG.  2   . The decorative printed layer  14  covers the base film  13 . The decorative printed layer  14  is a decorative layer for protecting and decorating the antenna device  10 , and is laminated on the base film  13  by printing, for example. The decorative layer is not limited to the decorative printed layer  14 , and may be formed by laminating a decorative film. 
     The topcoat layer  15  is provided on a surface of the decorative printed layer  14  facing away from the vehicle  100 , that is, facing upward in  FIG.  2   . The topcoat layer  15  is a protective film that protects an outermost surface of the antenna device  10 . The topcoat layer  15  is formed by applying a coating material to the decorative printed layer  14 , for example. 
     The antenna element  11  is laminated on the base film  13 . The antenna element  11  is provided between the vehicle  100  and the base film  13 , that is, downward of the base film  13  in  FIG.  2   . The antenna element  11  is realized, for example, by a conductive foil having a thickness of approximately 10 μm to 50 μm. 
     The conductive foil is formed of a conductive material, such as copper, having electrically conductivity. The conductive foil may have a flexible and bendable structure, and may be made of a foil-like material, or may be formed by, for example, electrolytic or electroless plating. 
     The antenna device  10  is fixed to the roof  101  by being attached to the roof  101  with an adhesive layer  19  made of an adhesive. The adhesive layer  19  is provided between the vehicle  100  and the base film  13  and between the vehicle  100  and the antenna element  11 , that is, downward of the base film  13  and the antenna element  11  in  FIG.  2   . 
     The antenna element  11  includes a radiating portion  16  that constitutes an electrical wire and transmits and receives a radio wave, and feeder lines  23 ,  24  that are electrically connected to an in-vehicle electronic device such as a communication device. The antenna element  11  has a substantially L-shape as shown in  FIG.  1   . The antenna element  11  has a rod shape or a line shape. 
     The radiating portion  16  extends from a power supply unit  18  to a position on the roof  101 . The power supply unit  18  is provided on the vehicle body frame  102  including a metal material. A length of the radiating portion  16  is set according to a wavelength A of the radio wave to be transmitted and received. 
     The radiating portion  16  does not function as an antenna if it is close to the vehicle body frame  102  and the roof  101 . Thus, the radiating portion  16  includes the magnetic member  12  provided on a surface of the radiating portion  16  facing the roof  101 . The magnetic member  12  separates the radiating portion  16  and the roof  101  in terms of high frequency. The magnetic member  12  is provided between the radiating portion  16  and the roof  101 . The magnetic member  12  functions as a blocking member that blocks the radio-wave connection between the radiating portion  16  and the roof  101 . The magnetic member  12  electromagnetically separates the radiating portion  16  and the roof  101 . A shielding member is not limited to the magnetic member  12 , and may be a radio wave absorber that absorbs the radio wave. 
     The radiating portion  16  has a vertical portion  21 , a horizontal portion  22  and a connecting portion  20 . The horizontal portion  22  of the radiating portion  16  extends in a left-right direction in  FIG.  1    and is arranged on the roof  101 . The horizontal portion  22  extends in a horizontal plane when the vehicle  100  is on the horizontal plane. The horizontal portion  22  mainly receives a horizontally polarized wave. Since the horizontal portion  22  extends on the roof  101 , there is not radio wave shielding object, and the horizontal portion  22  is capable of transmitting and receiving the radio wave in 360-degree directions on the horizontal plane. A length of the horizontal portion  22  is preferably λ/4, for example. “λ/4” means the length of one quarter of the wavelength λ. 
     The vertical portion  21  of the radiating portion  16  is a part of a portion extending in an up-down direction of  FIG.  1    and has a range indicated by an arrow V in  FIG.  3   . The connecting portion  20  connects the vertical portion  21  and the horizontal portion  22 . The connecting portion  20  is a part of the portion extending in the up-down direction of  FIG.  1   . The connecting portion  20  connects a left end of the horizontal portion  22  and an upper end of the vertical portion  21  in  FIG.  1   . 
     The vertical portion  21  is bent in a direction tilted from an extending direction of the horizontal portion  22 . The bending direction is tilted from a horizontal direction without being tilted in the horizontal plane. In the present embodiment, the vertical portion  21  is bent at two points into a Z shape along the roof  101 . The vertical portion  21  extends through a waterproof structure located between the roof  101  and a rear window  104 . A gap between the roof  101  and the rear window  104  is filled with a sealing structure  105  using sealing materials, thereby ensuring a waterproof property. When the roof  101  and the rear window  104  are arranged to cooperatively form an outer smooth peripheral surface of the vehicle  100  as shown in  FIG.  3   , the sealing structure  105  causes a height difference in the vertical portion  21  because the rear window  104  is thicker. At least a portion of the vertical portion  21  having this height difference extends in a vertical direction when the vehicle  100  is on the horizontal plane, and receives horizontally polarized waves well. 
     A part of the vertical portion  21  extending through the sealing structure  105  of the rear window  104  is installed at a vertical angle or an angle suitable for transmission and reception of the vertically polarized wave. The length in the vertical direction indicated by the arrow V in  FIG.  3    may be set larger than a tenth of the wavelength A of transmission and reception. 
     As shown in  FIG.  1   , a wire  17  includes a signal feeder line  23  and a ground feeder line  24 . The signal feeder line  23  is connected to the antenna element  11 . The ground feeder line  24  includes a ground connecting portion  25  at one end of the ground feeder line  24 . The ground connecting portion  25  is connected to the power supply unit  18  of the vehicle body frame  102 . The other end of the ground feeder line  24  is connected to the in-vehicle electronic device. One end of the signal feeder line  23  is connected to the antenna element  11 , and the other end of the signal feeder line  23  is connected to the in-vehicle electronic device. 
     The ground connecting portion  25  is arranged adjacent to the signal feeder line  23 , as shown in  FIG.  1   . In addition,  FIG.  3    shows a relationship between the vehicle body frame  102  and the power supply unit  18 . A coating film of the vehicle body frame  102  and the base film  13  are provided between the ground connecting portion  25  and the power supply unit  18 . Thus, the ground connecting portion  25  is arranged adjacent to the power supply unit  18  of the vehicle body frame  102 . As a result, the ground connecting portion  25  and the power supply unit  18  form high-frequency capacitive coupling. The ground connecting portion  25  provides a ground potential by arranging adjacent to the power supply unit  18  of the vehicle body frame  102 . The antenna device  10  is connected to the in-vehicle electronic device via a coaxial cable  106 . An inner conductor of the coaxial cable  106  is connected to the signal feeder line  23 . An outer conductor of the coaxial cable  106  is connected to the ground feeder line  24 . 
     In the present embodiment, the ground potential of the ground connecting portion  25  is coupled with the vehicle body frame  102  by the high-frequency capacitive coupling. Alternatively, a metal of the vehicle body frame  102  and the ground connecting portion  25  may be directly electrically connected. An elastic member  107  is provided below the ground connecting portion  25 . The gap between the ground connecting portion  25  and the roof lining  103  is filled with the elastic member. The elastic member  107  stably supports the ground connecting portion  25  and the power supply unit  18  of the vehicle body frame  102 . 
     Further, the power supply unit  18  on the vehicle body frame  102  is arranged at a position so as not to face the vertical portion  21  in the vertical direction. More specifically, as shown in  FIG.  3   , the power supply unit  18  is provided at a lower end portion of the vertical portion  21  where the antenna element  11  is bent frontward in a vehicle front-rear direction. If the power supply unit  18  is shifted from the position in the vehicle frontward direction, that is, in a leftward direction of  FIG.  3   , the power supply unit  18  and the vertical portion  21  face each other in the vertical direction. In this case, current directions are opposite between the vertical portion  21  and the power supply unit  18 , and an electric field may be canceled, resulting in decrease in signal strength. Therefore, as in the present embodiment, the power supply unit  18  is provided rearward of a part of the bent vertical portion  21  in the vehicle front-rear direction. 
     As shown in  FIGS.  4  and  5   , the antenna device  10 , as described above, extends from an upper surface of the roof  101  through the sealing structure  105  of the rear window  104  to the vehicle compartment, specifically, to the roof lining  103 .  FIG.  6    shows a cross-sectional view illustrating the sealing structure  105 , and the sealing materials  108 , 109  are provided on both surfaces of the antenna device  10 . More specifically, a first sealing material  108  is provided between the antenna device  10  and a sealing surface of the roof  101  to ensure the waterproof property and a dustproof property. A second sealing material  109  is provided between the rear window  104  and the antenna device  10  and between the rear window  104  and the sealing surface of the roof  101  to ensure the waterproof property and the dustproof property. The second sealing material  109  is for fixing the rear window  104 , and the rear window  104  is attached to the roof  101  via the second sealing material  109 . Thus, it is possible to ensure the waterproof property and the dustproof property in a portion extending through the sealing structure  105  of the antenna device  10 . 
     As described above, according to the attachment structure for the antenna device  10  of the present embodiment, the antenna element  11  is arranged on the roof  101  of the vehicle  100 , and the wire  17  electrically connects the antenna element  11  and the power supply unit  18  provided inside the vehicle  100 . The wire  17  extends through the waterproof structure located between the roof  101  and the member provided at a peripheral edge of the roof  101 . The member that is, for example, a window, a spoiler, or a molded resin, is attached to the peripheral edge of the roof  101 , thereby constituting the vehicle  100 . The waterproof property can be ensured by the waterproof structure through which the wire  17  extends, since the waterproof structure is located between the peripheral edge of the roof  101  and the member. As a result, the wire  17  can be drawn into an interior of the vehicle  100  from an upper side of the roof  101  without an opening formed on the roof  101  for the wire  17 . Therefore, the antenna element  11  of the antenna device  10  can be attached to the roof  101  without providing an opening in the roof  101 . 
     Further, in the present embodiment, the wire  17  extends through the sealing structure  105  between the roof  101  and the window of the vehicle  100 , specifically, the rear window  104 . The window of the vehicle  100  is attached to the roof  101  using the second sealing material  109 . Since the wire extends through the second sealing material  109 , the waterproof property can be ensured by the second sealing material  109 . In addition, the attachment structure can be realized by installing the antenna device  10  and extending the wire in advance in the same window attachment process as in an existing vehicle  100 . 
     Furthermore, in the present embodiment, the antenna element  11  has the horizontal portion  22  and the vertical portion  21 . The horizontal portion  22  functions as a first antenna element that extends on the roof  101  and mainly receives the horizontally polarized wave. The vertical portion  21  has a part that extends through the waterproof structure in the extending direction tilted from a direction in which the horizontal portion  22  extends. The vertical portion  21  functions as a second antenna element that mainly receives the vertically polarized wave. The vertical portion  21  extending through the sealing structure  105  of the rear window  104  tilts from the horizontal portion  22 , and can be set at an angle so as to easily receive the vertically polarized wave. By adopting this structure, the antenna element  11  can be extended on the roof  101  without making an opening in the roof  101 , and further, the vertically polarized wave can be transmitted and received, and an attachment structure for the antenna device  10  having a flat structure on the roof  101  can be provided. 
     Further, in the present embodiment, the magnetic member  12  is provided between the antenna element  11  and the roof  101 , and blocks the radio-wave connection between the antenna element  11  and the roof  101 . Thus, even if the roof  101  is made of metal, it is possible to realize the antenna device  10  that transmits and receives the radio wave while reducing an influence of the roof  101 . 
     Furthermore, in the present embodiment, the antenna device  10  further includes the decorative printed layer  14  provided outside the antenna element  11  and decorating the antenna element  11 . Although the roof  101  forms an appearance of the vehicle  100 , deterioration in visual appearance of the antenna device  10  can be reduced by the decorative printed layer  14 . 
     In the present embodiment, the antenna device  10  has the ground connecting portion  25  in which a foil-like radiating portion  16  is provided on the thin base film  13 . The ground connecting portion  25  is arranged adjacent to the vehicle body frame  102  in the vehicle compartment. Then, a tip end of the radiating portion  16  is arranged on the roof  101  outside the vehicle compartment. The wire extends through the sealing structure  105  between the rear window  104  and the roof  101 , while the sealing structure can be ensured the waterproof property and the dustproof property. 
     As a result, the antenna device in the present embodiment is not an antenna device with a shark fin shape arranged on a roof of a vehicle. Thus, since the antenna device does not have a shape which protrudes upward from the roof  101 , deterioration in visual appearance of the vehicle  100  can be reduced. Moreover, since the sealing structure  105  also ensures the waterproof property, a waterproof structure dedicated to the wire of the antenna device  10  and its parts are not required, and the wire can be drawn into the vehicle  100  without providing an opening on the roof  101 . 
     Furthermore, since the antenna element  11  is installed on the roof  101 , there is not radio wave shielding object in 360-degrees on the horizontal plane, so a gain can be obtained by the antenna element in all directions. Therefore, the degree of freedom in installing the antenna element  11  can be improved. 
     Second Embodiment 
     Next, a second embodiment of the present disclosure will be described with reference to  FIGS.  7  and  8   . The second embodiment is characterized in that an antenna device  10 A further includes a resin member  110  covering an outside of an antenna element  11 . Moreover, a configuration of the antenna element  11  and an arrangement of a power supply unit  18  of the present embodiment are different from those of the above-described first embodiment. 
     In the present embodiment, a roof  101  includes a frame member  111 , as shown in  FIG.  7   . The frame member  111  is a part of a vehicle body frame  102 . In other words, the part of the vehicle body frame  102  is not covered with the roof  101 , and the part of the vehicle body frame  102  is exposed to an outside. 
     In the present embodiment, as shown in  FIG.  7   , the frame member  111  is provided at a rear end of the roof  101  instead of a rear window  104 . A connecting portion  20  between the roof  101  and the frame member  111  is joined by welding to form a waterproof structure. A space between the frame member  111  and the rear window  104  is filled with a sealing structure  105  using sealing materials  108 ,  109 , thereby providing a waterproof property. 
     The antenna device  10 A is arranged on the frame member  111  as shown in  FIG.  7   . The frame member  111  is covered with the resin member  110 . Therefore, the antenna device  10 A is arranged between the frame member  111  and the resin member  110 . The resin member  110  is a decorative part that includes a resin material and forms an outer shape of a vehicle  100 . The resin member  110  is realized by, for example, a molded resin and a spoiler. Since the antenna device  10 A is covered with the resin member  110 , no decorative surface is required. 
     The antenna element  11  has a substantially N-shape as shown in  FIG.  8   . As shown in  FIG.  8   , a radiating portion  16  of the antenna element  11  has a straight shape in which a vertical portion  21  and a horizontal portion  22  are continuous. The horizontal portion  22  of the radiating portion  16  is a part of a portion extending in an up-down direction in  FIG.  8    and arranged on the roof  101 . The vertical portion  21  of the radiating portion  16  is another part of the portion extending in the up-down direction in  FIG.  8   , similar to the horizontal portion  22 . In other words, the horizontal portion  22  of the present embodiment is different from the horizontal portion  22  of the first embodiment in extending direction. 
     As shown in  FIG.  8   , a wire  17  has an L-shape and is continuous with an !-shape of the radiating portion  16 . A ground connecting portion  25  of the wire  17  is arranged apart from the radiating portion  16  in a left-right direction in  FIG.  8   . As shown in  FIG.  7   , the ground connecting portion  25  appears to face the vertical portion  21  in the vertical direction. However, since the ground connecting portion  25  is arranged apart from the radiating portion  16  in the horizontal direction as described above, the ground connecting portion  25  is not arranged so as to face the vertical portion  21  and is shifted from the vertical portion  21  in a horizontal direction when the vehicle  100  is viewed in the vertical direction. 
     As shown in  FIG.  7   , the power supply unit  18  is provided frontward of a bent part of the lower end portion of the vertical portion  21  where the antenna element  11  is bent frontward in a vehicle front-rear direction. Thus, since the ground connecting portion  25  is arranged adjacent to a flat portion of the vehicle body frame  102 , the ground potential can be provided more reliably. 
     In the present embodiment, the antenna device  10 A further includes the resin member  110  covering an outside of the antenna element  11 . Thus, in the antenna device  10 A, no decorative layer is required. The configuration of the antenna device  10 A can be simplified. 
     Other Embodiments 
     The present disclosure is not limited to the preferred embodiments of the present disclosure described above. Various modifications may be made without departing from the subject matters of the present disclosure. 
     It should be understood that the configurations described in the above-described embodiments are example configurations, and the present disclosure is not limited to the foregoing descriptions. The scope of the present disclosure encompasses claims and various modifications of claims within equivalents thereof. 
     In the above-described first embodiment, the roof  101  includes a metal plate, but the configuration is not limited to this. If the roof  101  of the vehicle  100  is made of a nonmetallic material such as a resin, the shielding member arranged on the vehicle surface of the radiating portion  16  is not necessary. 
     In the above-described first embodiment, the number of the antenna element  11  is one, but the number is not limited to one, and may be two or more. For example, the antenna device  10  may have two antenna elements  11 , one of the two antenna elements  11  may serve as a so-called main antenna for receiving the horizontally polarized wave, and the other may serve as a sub-antenna for receiving the vertically polarized wave. The antenna element  11  may also have other shapes, such as a loop antenna. 
     In the above-described first embodiment, the waterproof structure is the sealing structure  105 , but the configuration is not limited to such structure. For example, the waterproof structure may be a labyrinth structure, a fitting structure, and a waterproof structure using other members such as a waterproof packing. 
     In the above-described first embodiment, the sealing structure  105  is arranged between the roof  101  and the rear window  104 , but the sealing structure  105  is not limited to the rear window  104 . For example, the sealing structure  105  may be arranged between the roof  101  and a fixed window that does not have an opening/closing mechanism, and the fixed window may be a front window or a sunroof. 
     While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. To the contrary, the present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various elements are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.