Vehicle window glass

Abstract

Provided is a vehicle window glass that makes it possible to suppress decreases in the radiation efficiency of radio waves radiated from a planar antenna. Vehicle window glass (1) according to one aspect of the present disclosure comprises: window glass (10) that is attached to an opening in a vehicle; and a planar antenna (20) that is attached to a main surface on the vehicle interior side of the window glass (10). The planar antenna (20) is configured such that a conductor layer (22) is disposed on the surface of a first dielectric layer (21) and the distance d between the conductor layer (22) and the main surface of the window glass (10) is 0.2-20.0 mm.

Description

Window glass for vehicle

[0001] The present disclosure relates to window glass for vehicles.

[0002] In recent years, in means of transportation such as automobiles, the development of automobiles capable of realizing high-capacity communication using radio waves in the 4G-LTE / 5G frequency band and high-level autonomous driving as infotainment has been accelerating. For this reason, in order to transmit and receive radio waves in a predetermined frequency band, an antenna having a conductor tends to be mounted on a vehicle. For example, in order to obtain information in front of the vehicle, it has also been considered to mount such an antenna on window glass for vehicles such as a windshield.

[0003] Patent Document 1 discloses a technique related to window glass for vehicles provided with an antenna capable of communicating in a wide band. Further, Patent Document 2 discloses a technique related to a wide-band planar antenna capable of supporting a relatively high frequency band up to about 6 GHz.

[0004] International Publication No. 2017 / 018324 International Publication No. 2023 / 068151

[0005] As described in the background art, in recent years, in order to transmit and receive radio waves in a predetermined frequency band, an antenna having a conductor tends to be mounted on a vehicle. For example, by providing a planar antenna on window glass for vehicles attached to an opening of a vehicle, radio waves in a predetermined frequency band can be transmitted and received.

[0006] However, if the position of the planar antenna attached to the window glass for vehicles is not appropriate, there is a risk that the radiation efficiency of the planar antenna will decrease. Specifically, when the distance between the planar antenna and the window glass for vehicles is not appropriate, there is a problem that radio waves propagate from the planar antenna to the window glass for vehicles and the radiation efficiency of the planar antenna decreases.

[0007] In view of the above problems, an object of the present disclosure is to provide window glass for vehicles capable of suppressing a decrease in the radiation efficiency of radio waves radiated from a planar antenna.

[0008] The window glass for vehicles according to one aspect of the present disclosure has the following configuration.

[0009] [1] A window glass for a vehicle, comprising a window glass installed in an opening of a vehicle, and a planar antenna attached to the main surface of the window glass on the vehicle side, wherein the planar antenna has a conductor layer arranged on the surface of a first dielectric layer, and the distance between the conductor layer and the main surface of the window glass is 0.2 mm or more and 20.0 mm or less.

[0010] [2] The vehicle window glass according to [1], wherein the distance between the conductor layer and the main surface of the window glass is 0.4 mm or more and 20.0 mm or less.

[0011] [3] The vehicle window glass according to [1] or [2], wherein a second dielectric layer is interposed between the first dielectric layer and the main surface of the window glass.

[0012] [4] The vehicle window glass according to [3], which includes a region in which the window glass, the second dielectric layer, the first dielectric layer, and the conductor layer are laminated in that order.

[0013] [5] The vehicle window glass according to [3], which includes a region in which the window glass, the second dielectric layer, the conductor layer, and the first dielectric layer are laminated in that order.

[0014] [6] The vehicle window glass according to any one of [3] to [5], wherein the second dielectric layer is an adhesive layer.

[0015] [7] The vehicle window glass according to any one of [3] to [5], wherein the second dielectric layer is an adhesive layer and an air layer.

[0016] [8] The vehicle window glass according to any one of [3] to [5], wherein the second dielectric layer consists of a resin layer and an air layer laminated adjacent to each other.

[0017] [9] The vehicle window glass according to any one of [3] to [5], wherein the planar antenna is held by a bracket attached to the main surface of the window glass.

[0018]

[10] The vehicle window glass according to [9], wherein the second dielectric layer is made of the same material as the bracket.

[0019]

[11] The vehicle window glass according to [9], wherein the second dielectric layer is an air layer.

[0020]

[12] The window glass for a vehicle according to any one of [1] to

[11] , wherein the window glass is laminated glass having a first glass plate disposed on the outside of the vehicle, a second glass plate disposed on the inside of the vehicle, and an intermediate layer sandwiched between the first glass plate and the second glass plate.

[0021]

[13] The planar antenna is positioned so as to be spaced apart on the interior side of the second glass plate with respect to the main surface on the interior side of the vehicle, as described in

[12] .

[0022]

[14] The planar antenna is arranged to be spaced apart on the interior side of the first glass plate with respect to the main surface on the interior side of the vehicle, as described in

[12] .

[0023]

[15] The vehicle window glass according to any one of [1] to

[14] , wherein the conductor layer is a flat conductor with slots formed therein.

[0024]

[16] The vehicle window glass according to

[15] , wherein the planar antenna comprises a feed electrode and a ground electrode in the conductor layer.

[0025]

[17] The planar antenna is capable of transmitting and receiving radio waves in the frequency band of 600 MHz to 6 GHz, a vehicle window glass according to any one of [1] to

[16] .

[0026] This disclosure provides a vehicle window glass that can suppress the decrease in the radiation efficiency of radio waves emitted from a planar antenna.

[0027] This is a plan view showing an example of the configuration of a vehicle window glass according to the embodiment. This is a cross-sectional view showing an example of the configuration of a vehicle window glass according to the embodiment. This is a cross-sectional view showing another example of the configuration of a vehicle window glass according to the embodiment. This is a cross-sectional view showing another example of the configuration of a vehicle window glass according to the embodiment. This is a cross-sectional view showing another example of the configuration of a vehicle window glass according to the embodiment. This is a cross-sectional view illustrating the vehicle window glass used in the embodiment. This is a graph showing the relationship between the glass-antenna distance and radiation efficiency. This is a plan view illustrating the vehicle window glass used in the embodiment. This is a cross-sectional view illustrating the vehicle window glass used in the embodiment. This is a graph showing the relationship between the glass-antenna distance and beam half-width (HPBW). This is a cross-sectional view showing the electric field strength distribution in the vehicle window glass. This is a graph showing the relationship between the glass-antenna distance and normalized electric field strength.

[0028] The embodiments will now be described with reference to the drawings. Figure 1 is a plan view showing an example of the configuration of a vehicle window glass according to the embodiment. Figure 2 is a cross-sectional view taken along the cutting line II-II in Figure 1.

[0029] As shown in Figure 1, the vehicle window glass 1 according to this embodiment comprises a window glass 10 installed in the opening of a vehicle, and a planar antenna 20 attached to the main surface of the window glass 10 on the interior side of the vehicle. The vehicle window glass 1 according to this embodiment is typically a car windshield. The window glass 10 may be a single glass plate, or it may be laminated glass made by laminating two or more glass plates. When the vehicle window glass 1 is a windshield, it is preferable that the window glass 10 is laminated glass. The case in which the window glass 10 is laminated glass will be described below. Note that the vehicle window glass 1 according to this embodiment can be applied not only to windshields, but also to rear windows, side windows, roof windows, etc.

[0030] As shown in Figure 1, the window glass 10 is attached to the frame 18 of the vehicle body. In other words, the window glass 10 is attached to the opening formed by the frame 18 of the vehicle body. A planar antenna 20 is provided on the window glass 10. The planar antenna 20 is typically attached to the main surface of the window glass 10 on the interior side. Although Figure 1 shows an example configuration in which the planar antenna 20 is attached to the upper right side of the window glass 10, the position of the planar antenna 20 can be determined arbitrarily.

[0031] As shown in Figure 2, the vehicle window glass 1 comprises a window glass 10 and a planar antenna 20 attached to the main surface of the window glass 10 on the vehicle side. The window glass 10 comprises a first glass plate 11, a second glass plate 12, and an intermediate layer 13 disposed between the first glass plate 11 and the second glass plate 12.

[0032] The window glass 10 may be flat or curved. It may also have a shape that includes both a flat and a curved surface. The first glass plate 11 and the second glass plate 12 may each be flat or curved. The curved plate may be a simple curved shape that curves in one direction, or a three-dimensional shape that curves in two or more directions. The three-dimensional shape may be, for example, a double curved shape that curves in two orthogonal directions. In the following example, the case in which both the first glass plate 11 and the second glass plate 12 are made of flat plates will be described, but the same description can be applied when at least one of them is made of a curved plate.

[0033] The outer edge shapes of the first glass plate 11 and the second glass plate 12 in plan view can be any shape, but for example, rectangular, trapezoidal, and triangular shapes are preferred. In this embodiment, when the vehicle window glass 1 is installed in a vehicle, the first glass plate 11 is positioned on the outside of the vehicle and the second glass plate 12 is positioned on the inside of the vehicle.

[0034] The first and second glass plates 11 and 12 can be made of, for example, transparent inorganic glass. For the first and second glass plates 11 and 12, for example, soda-lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, quartz glass, etc., may be used. The first and second glass plates 11 and 12 are manufactured using, for example, the float method, the fusion method, etc., but are not limited to these methods.

[0035] The thickness of each of the first and second glass plates 11 and 12 is, for example, 0.1 mm to 10 mm, preferably 0.3 mm to 3.0 mm, more preferably 1.1 mm to 2.6 mm, and even more preferably 1.7 mm to 2.1 mm from the viewpoint of resistance to flying stone impact. The thicknesses of the first and second glass plates 11 and 12 may be the same or different. For example, the thickness of the first glass plate 11, which is located on the outside of the vehicle, may be greater than the thickness of the second glass plate 12, which is located on the inside of the vehicle. When the thickness of the first glass plate 11, which is located on the outside of the vehicle, is increased in this way, the strength of the vehicle window glass 1 against objects flying towards the vehicle window glass 1 is improved.

[0036] The intermediate layer 13 is positioned so as to be sandwiched between the first glass plate 11 and the second glass plate 12. The thickness of the intermediate layer 13 is not particularly limited, but is preferably 1.10 mm or less. Furthermore, the thickness of the intermediate layer 13 is preferably 0.50 mm or more, and more preferably 0.70 mm or more. By setting the thickness of the intermediate layer 13 within this range, the transparency of the vehicle window glass can be ensured and the weight of the vehicle window glass can be prevented from becoming excessively large.

[0037] The intermediate layer 13 can be made using materials such as polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), cycloolefin polymer, urethane resin, or polyvinylidene fluoride resin (PVDF).

[0038] In this embodiment, when forming the window glass 10, the first glass plate 11, the intermediate layer 13, and the second glass plate 12 are stacked in this order and placed in a vacuum bag such as a rubber bag. Then, this vacuum bag is connected to an exhaust system, and the pressure inside the vacuum bag is reduced by vacuum suction (degassing) to a degree of reduced pressure (absolute pressure) of approximately -65 kPa to -100 kPa, and then heated and pressurized at a temperature of approximately 70°C to 110°C. Furthermore, by performing a bonding treatment under conditions of heating and pressurizing at a temperature of approximately 100°C to 140°C and a pressure of 0.6 MPa to 1.3 MPa, a window glass 10 with excellent durability can be obtained. Note that the method of forming the window glass 10 is not limited to this method, and the vehicle window glass 1 may be formed using other manufacturing methods.

[0039] As shown in Figure 2, a planar antenna 20 is attached to the main inner surface of the window glass 10 (specifically, the main inner surface of the second glass plate 12). The planar antenna 20 comprises a base material (first dielectric layer) 21 and a conductor layer 22. Specifically, the conductor layer 22 is arranged on the surface of the base material 21 of the planar antenna 20. The conductor layer 22 of the planar antenna 20 may be a flat conductor with slots formed therein. For example, the planar antenna may have a feed electrode and a ground electrode on the conductor layer 22. The feed electrode and the ground electrode are connected to a transmission line (not shown). The shapes of the feed electrode and the ground electrode can be arbitrarily determined according to the frequency band of the radio waves transmitted and received by the planar antenna 20. For example, the planar antenna 20 is configured to transmit and receive radio waves in the frequency band of 600 MHz to 6 GHz.

[0040] The substrate 21 can be made of a dielectric material. For example, the substrate 21 may be made of a resin film or a rigid substrate having a predetermined thickness. For example, the substrate 21 may be made of a resin film such as a TAC (Triacetylcellulose) film or a PET (PolyEthylene Terephthalate) film, or a rigid substrate such as a glass epoxy substrate. The thickness of the substrate 21 is, for example, 0.1 mm or more and 20 mm or less. The dielectric constant of the substrate 21 is, for example, 1.0 to 5.0.

[0041] The conductive layer 22 can be constructed using a conductive material. For example, the conductive layer 22 can be constructed using a metallic material such as copper or silver. The thickness of the conductive layer 22 is, for example, 3 μm or more and 100 μm or less.

[0042] In the configuration example shown in FIG. 2, the surface of the substrate 21 side of the planar antenna 20 is adhered to the main surface of the window glass 10 via an adhesive layer (second dielectric layer) 30. That is, an adhesive layer (second dielectric layer) 30 is interposed between the substrate (first dielectric layer) 21 and the main surface of the window glass 10. The thickness of the adhesive layer 30 is, for example, 0.1 mm or more and 20.0 mm or less. The dielectric constant of the adhesive layer 30 is, for example, 1.0 to 4.0. The adhesive layer 30 includes, for example, a film layer and adhesive material layers provided on both surfaces of the film layer. In this case, an acrylic foam or a polyolefin-based foam can be used for the film layer. Also, an acrylic-based adhesive material can be used for the adhesive material layer.

[0043] As described above, the vehicle window glass 1 shown in FIG. 2 has a configuration in which the window glass 10, the adhesive layer (second dielectric layer) 30, the substrate (first dielectric layer) 21, and the conductor layer 22 are laminated in this order in the region where the planar antenna 20 is disposed.

[0044] Further, the conductor layer 22 of the planar antenna 20 is disposed so as to be separated from the inner side of the vehicle by a distance d with reference to the main surface on the inner side of the vehicle of the second glass plate 12 of the window glass 10. In the present embodiment, it is preferable that the distance d between the conductor layer 22 and the main surface of the window glass 10 is 0.2 mm or more and 20.0 mm or less, and more preferably 0.4 mm or more and 20.0 mm or less.

[0045] By setting the distance d between the conductor layer 22 and the main surface of the window glass 10 to 0.2 mm or more, propagation of radio waves from the planar antenna 20 to the window glass 10 can be suppressed, and a decrease in the radiation efficiency of the planar antenna 20 can be suppressed. Also, the beam width of the radio waves radiated from the planar antenna 20 can be widened. Further, by setting the distance d between the conductor layer 22 and the main surface of the window glass 10 to 20.0 mm or less, protrusion of the planar antenna 20 from the main surface of the window glass 10 can be suppressed, and the planar antenna 20 can be installed compactly.

[0046] The lower limit of the distance d between the conductor layer 22 and the main surface of the window glass 10 may be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 2.0 mm, 3.0 mm, or 4.0 mm. Further, the upper limit of the distance d between the conductor layer 22 and the main surface of the window glass 10 may be 19.0 mm, 18.0 mm, 17.0 mm, 16.0 mm, 15.0 mm, 14.0 mm, 13.0 mm, 12.0 mm, or 11.0 mm.

[0047] In the configuration example shown in FIG. 2, the distance d is determined by the thickness of the adhesive layer 30 and the thickness of the base material 21. That is, by adjusting the thickness of the adhesive layer 30 and the thickness of the base material 21, the distance d can be adjusted to an arbitrary distance.

[0048] As described above, in the present embodiment, the distance d between the conductor layer 22 and the main surface of the window glass 10 is configured to be separated by a predetermined distance. Therefore, it is possible to suppress the propagation of radio waves from the planar antenna 20 to the window glass 10, and thus it is possible to suppress a decrease in the radiation efficiency of the planar antenna 20. In addition, the beam width of the radio waves radiated from the planar antenna 20 can be widened.

[0049] Next, another configuration example of the vehicle window glass 1 according to the present embodiment will be described. FIGS. 3 to 6 are cross-sectional views showing another configuration example of the vehicle window glass according to the embodiment.

[0050] In the present embodiment, when attaching the planar antenna 20 to the window glass 10 as in the vehicle window glass 1a shown in FIG. 3, the surface of the planar antenna 20 on the conductor layer 22 side may be adhered to the main surface of the window glass 10 via the adhesive layer (second dielectric layer) 30. The vehicle window glass 1a shown in FIG. 3 has a configuration in which the window glass 10, the adhesive layer (second dielectric layer) 30, the conductor layer 22, and the base material (first dielectric layer) 21 are laminated in this order in the region where the planar antenna 20 is disposed. In the vehicle window glass 1a shown in FIG. 3, since the conductor layer 22 is configured to be sandwiched between the base material 21 and the adhesive layer 30, the conductor layer 22 can be protected from the external environment.

[0051] In the configuration example shown in FIG. 3, the distance d is determined by the thickness of the adhesive layer 30. That is, by adjusting the thickness of the adhesive layer 30, the distance d can be adjusted to an arbitrary distance.

[0052] In this embodiment, as shown in Figure 4, when attaching the planar antenna 20 to the window glass 10, adhesive layers (second dielectric layers) 30_1 and 30_2 may be provided at the ends of the surface of the planar antenna 20 facing the base material 21, thereby adhering the planar antenna 20 to the main surface of the window glass 10. In this case, a region where the adhesive layers (second dielectric layers) 30_1 and 30_2 are interposed and a region where the air layer (second dielectric layer) 35 is interposed are formed between the base material 21 and the main surface of the window glass 10.

[0053] In the example configuration shown in Figure 4, adhesive layers 30_1 and 30_2 are provided at the upper and lower ends of the planar antenna 20, respectively. However, the adhesive layer 30 may also be provided at the left and right ends of the planar antenna 20, or it may be provided around the entire perimeter of the planar antenna 20.

[0054] In the configuration example shown in Figure 4, the distance d is determined by the thickness of the adhesive layers 30_1 and 30_2 and the thickness of the substrate 21. In other words, by adjusting the thickness of the adhesive layers 30_1 and 30_2 and the thickness of the substrate 21, the distance d can be adjusted to any desired distance.

[0055] In this embodiment, the configuration shown in Figure 3 and the configuration shown in Figure 4 may be combined. That is, adhesive layers 30_1 and 30_2 may be provided at the ends of the surface of the planar antenna 20 on the conductor layer 22 side, and the planar antenna 20 may be bonded to the main surface of the window glass 10.

[0056] In this embodiment, the planar antenna 20 may be held by a bracket 33 attached to the main surface of the window glass 10, as shown in Figure 5, for example, in the vehicle window glass 1c. Specifically, the surface of the planar antenna 20 facing the base material 21 is attached to the inner surface of the bracket 33 that faces the vehicle. Then, the outer surface of the bracket 33 is attached to the main surface of the window glass 10. Adhesives can be used to bond the planar antenna 20 to the bracket 33, and to bond the bracket 33 to the window glass 10. The bracket 33 can be constructed using, for example, a case-shaped member. If a case-shaped bracket 33 is used, the planar antenna 20 can be protected from the external environment. The bracket 33 may be a resin layer made of a resin such as a thermosetting resin or a thermoplastic resin. Examples of resins include polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyolefins such as polyethylene (PE) and polypropylene (PP), polycarbonate (PC), polyamides such as nylon 6 and nylon 6,6 (PA), high heat-resistant polyamides based on terephthalic acid and isophthalic acid (PA6T, PA6I, PA6T / 6I, etc.), polyimide (PI), polyetherimide (PEI), acrylonitrile-butadiene-styrene (ABS), polyacetal (POM), polyvinyl chloride (PVC), epoxy (EP), and the like.

[0057] In the configuration example shown in Figure 5, a bracket (second dielectric layer) 33 and an air layer (second dielectric layer) 36 are interposed between the conductive layer 22 and the main surface of the window glass 10. That is, the resin layer (second dielectric layer) 33 and the air layer (second dielectric layer) 36 are laminated adjacent to each other. In this case, the distance d is determined by the shape of the bracket 33 (height of the bracket 33) and the thickness of the base material 21. In other words, the distance d can be adjusted to any distance by adjusting the shape of the bracket 33 and the thickness of the base material 21.

[0058] In this embodiment, the planar antenna 20 may be held by a bracket 33 attached to the main surface of the window glass 10, as shown in the vehicle window glass 1d in Figure 6. Specifically, the surface of the planar antenna 20 facing the base material 21 is attached to the inner surface of the bracket 33 on the vehicle side. Then, the outer surface of the bracket 33 is attached to the main surface of the window glass 10. Adhesives can be used to bond the planar antenna 20 to the bracket 33, and to bond the bracket 33 to the window glass 10. The bracket 33 can be constructed using, for example, a case-shaped member. If a case-shaped bracket 33 is used, the planar antenna 20 can be protected from the external environment.

[0059] In the configuration example shown in Figure 6, a bracket (second dielectric layer) 33 and a substrate (first dielectric layer) 21 are interposed between the conductor layer 22 and the main surface of the window glass 10. In this case, the distance d is determined by the shape of the bracket 33 (thickness of the bracket 33) and the thickness of the substrate 21. In other words, by adjusting the thickness of the bracket 33 and the thickness of the substrate 21, the distance d can be adjusted to any desired distance.

[0060] The vehicle window glass according to this embodiment has been described above, but the vehicle window glass according to this embodiment may have configurations other than those shown in Figures 2 to 6. That is, in this embodiment, any configuration is possible as long as the distance d between the conductor layer 22 of the planar antenna 20 and the main surface of the window glass 10 is a predetermined distance apart.

[0061] Furthermore, in this embodiment, if the window glass 10 is made of laminated glass, the planar antenna 20 may be sealed inside the window glass 10. In this case, the planar antenna 20 is positioned such that the conductor layer 22 of the planar antenna 20 is spaced apart on the interior side of the first glass plate 11, with reference to the interior main surface of the first glass plate 11. In other words, the planar antenna 20 is positioned such that the distance d between the conductor layer 22 of the planar antenna 20 and the interior main surface of the first glass plate 11 is within the above range.

[0062] When the planar antenna 20 is enclosed inside the window glass 10, it is preferable that the conductor layer 22 of the planar antenna 20 be positioned so as to be spaced apart on the outside of the vehicle with respect to the main surface of the second glass plate 12 on the outside of the vehicle. In other words, it is preferable that the distance d between the conductor layer 22 of the planar antenna 20 and the main surface of the second glass plate 12 on the outside of the vehicle be within the above range.

[0063] Next, we will describe some examples.

[0064] <Relationship between glass-antenna distance and radiation efficiency> To investigate the relationship between the glass-antenna distance and radiation efficiency, the simulation described below was performed. Figure 7 is a cross-sectional view illustrating the vehicle window glass used in the embodiment. The vehicle window glass 1 shown in Figure 7 has a structure in which a window glass 10, a dielectric layer 25, and a conductor layer 22 are laminated. The dielectric layer 25 corresponds to the substrate 21 and adhesive layer 30 mentioned above. In this simulation, the dielectric constant of the window glass 10 was set to 7.0, and the dielectric constant of the dielectric layer 25 was set to 1.0. The thickness of the window glass 10 was set to 4.0 mm. The distance d between the conductor layer 22 and the main surface of the window glass 10 (i.e., the thickness of the dielectric layer 25) was varied between 0 mm and 4 mm. Then, a high frequency of 0.5 to 6.0 GHz was supplied to the conductor layer 22, and the radiation efficiency was determined. The radiation efficiency was determined from the ratio of the power input to the antenna to the power radiated from the antenna.

[0065] Figure 8 is a graph showing the relationship between the distance between the glass and the antenna and the radiation efficiency. In the graph shown in Figure 8, the average value of the radiation efficiency in the range of 0.5 to 6 GHz is shown as the "frequency-averaged radiation efficiency". As shown in Figure 8, the radiation efficiency increased as the distance d between the conductor layer 22 and the main surface of the window glass 10 increased. In particular, the radiation efficiency was good when the distance between the conductor layer 22 and the main surface of the window glass 10 was 0.2 mm or more.

[0066] <Relationship between glass-antenna distance and beam half-power width> Next, to investigate the relationship between the glass-antenna distance and the beam half-power width (HPBW), the simulation described below was performed. Figures 9 and 10 are a plan view and a cross-sectional view, respectively, illustrating the vehicle window glass used in the embodiment. The cross-sectional view in Figure 10 corresponds to the cross-sectional view of the dashed line portion in Figure 9.

[0067] The vehicle window glass shown in Figure 10 has a structure in which a window glass 10, a dielectric layer 25, and a dipole antenna 27 are laminated. The dielectric layer 25 corresponds to the substrate 21 and adhesive layer 30 described above. The dipole antenna 27 corresponds to the conductor layer 22 described above. In this simulation, the dielectric constant of the window glass 10 was set to 7.0, and the dielectric constant of the dielectric layer 25 was set to 1.0. The thickness of the window glass 10 was set to 4.0 mm, the horizontal length to 500 mm, and the vertical length to 300 mm. The distance d between the dipole antenna 27 and the main surface of the window glass 10 (i.e., the thickness of the dielectric layer 25) was varied between 0 mm and 3 mm. High frequencies of 4 GHz, 5 GHz, and 6 GHz were fed to the dipole antenna 27, and the beam width at half maximum of the radio waves radiated from the dipole antenna 27 was determined. The beam width at half maximum was determined from the angular width at which the highest gain of the radiation pattern on the cross-section shown in Figure 10 was -3 dB.

[0068] Figure 11 is a graph showing the relationship between the glass-to-antenna distance d and the beam width at half maximum (HPBW). In the graph shown in Figure 11, the average value of the beam width at half maximum at 4 GHz, 5 GHz, and 6 GHz is shown as "frequency-averaged HPBW". As shown in Figure 11, when the glass-to-antenna distance d is 0.4 mm or more, the beam width at half maximum is high, and an improvement in beam width at half maximum is observed.

[0069] Figure 12 is a cross-sectional view showing the electric field strength distribution in a vehicle window glass. Figure 12 corresponds to the cross-section at the position indicated by the dashed line in Figure 9, and shows the electric field strength distribution in the cross-section of the window glass 10. In Figure 12, the electric field strength threshold is set to 35 dB (V / m), and areas where the electric field strength is higher than this threshold are shown in black, and areas where the electric field strength is lower than this threshold are shown in white. In other words, the black areas in Figure 12 indicate positions with high electric field strength. Figure 13 is a graph showing the relationship between the glass-antenna distance d and the normalized electric field strength. In Figure 13, the electric field strength when the glass-antenna distance d is 0 is normalized to 0.

[0070] As shown in Figures 12 and 13, at all frequencies of 4 GHz, 5 GHz, and 6 GHz, the electric field strength inside the window glass 10 decreased as the distance d between the glass and the antenna increased. Therefore, it can be said that the more the distance d between the glass and the antenna increased, the less radio waves propagated from the dipole antenna 27 to the window glass 10.

[0071] Furthermore, as shown in Figure 12, the electric field strength inside the window glass 10 increased as the frequency increased to 4 GHz, 5 GHz, and 6 GHz. Therefore, it can be said that the higher the frequency, the more radio waves propagated from the dipole antenna 27 to the window glass 10. Focusing on frequencies of 5 GHz and 6 GHz, when the glass-antenna distance d was 0, a very large amount of radio waves propagated from the dipole antenna 27 to the window glass 10. However, when the glass-antenna distance d was 0.4 and 0.8, the amount of radio waves propagated from the dipole antenna 27 to the window glass 10 decreased significantly.

[0072] In other words, as shown in Figures 12 and 13, the higher the frequency, the more radio waves propagate from the dipole antenna 27 to the window glass 10. However, by making the distance d between the glass and the antenna 0.4 mm or more, it was possible to significantly reduce the amount of radio waves propagating from the dipole antenna 27 to the window glass 10.

[0073] Although the present invention has been described above in accordance with the above embodiments, the present invention is not limited to the configuration of the above embodiments, and of course includes various modifications, alterations, and combinations that can be made by a person skilled in the art within the scope of the claims of the present patent application.

[0074] This application claims priority based on Japanese Patent Application No. 2024-158320, filed on 12 September 2024, and incorporates all of its disclosures herein.

[0075] 1, 1a-1d Vehicle window glass 10 Window glass 11 First glass plate 12 Second glass plate 13 Intermediate layer 18 Frame 20 Planar antenna 21 Substrate 22 Conductor layer 25 Dielectric layer 27 Dipole antenna 30, 30_1, 30_2 Adhesive layer 33 Bracket 35, 36 Air layer

Claims

1. A window glass for a vehicle, comprising: a window glass installed in an opening of a vehicle; and a planar antenna attached to the main surface of the window glass on the vehicle side, wherein the planar antenna has a conductor layer arranged on the surface of a first dielectric layer, and the distance between the conductor layer and the main surface of the window glass is 0.2 mm or more and 20.0 mm or less.

2. The vehicle window glass according to claim 1, wherein the distance between the conductive layer and the main surface of the window glass is 0.4 mm or more and 20.0 mm or less.

3. The vehicle window glass according to claim 1 or 2, wherein a second dielectric layer is interposed between the first dielectric layer and the main surface of the window glass.

4. The vehicle window glass according to claim 3, wherein the vehicle window glass includes a region in which the window glass, the second dielectric layer, the first dielectric layer, and the conductor layer are laminated in that order.

5. The vehicle window glass according to claim 3, wherein the vehicle window glass includes a region in which the window glass, the second dielectric layer, the conductor layer, and the first dielectric layer are laminated in that order.

6. The vehicle window glass according to claim 3, wherein the second dielectric layer is an adhesive layer.

7. The vehicle window glass according to claim 3, wherein the second dielectric layer is an adhesive layer and an air layer.

8. The vehicle window glass according to claim 3, wherein the second dielectric layer comprises a resin layer and an air layer laminated adjacent to each other.

9. The vehicle window glass according to claim 3, wherein the planar antenna is held by a bracket attached to the main surface of the window glass.

10. The vehicle window glass according to claim 9, wherein the second dielectric layer is made of the same material as the bracket.

11. The vehicle window glass according to claim 9, wherein the second dielectric layer is an air layer.

12. The window glass for a vehicle according to claim 1 or 2, wherein the window glass is laminated glass having a first glass plate disposed on the outside of the vehicle, a second glass plate disposed on the inside of the vehicle, and an intermediate layer sandwiched between the first glass plate and the second glass plate.

13. The vehicle window glass according to claim 12, wherein the planar antenna is arranged to be spaced apart on the interior side with respect to the main surface of the second glass plate on the interior side.

14. The vehicle window glass according to claim 12, wherein the planar antenna is arranged to be spaced apart on the interior side of the first glass plate with respect to the main surface on the interior side of the vehicle.

15. The vehicle window glass according to claim 1 or 2, wherein the conductor layer is a flat conductor with slots formed therein.

16. The vehicle window glass according to claim 15, wherein the planar antenna comprises a feed electrode and a ground electrode in the conductor layer.

17. The vehicle window glass according to claim 15, wherein the planar antenna is capable of transmitting and receiving radio waves in the frequency band of 600 MHz to 6 GHz.

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