Glass pane for a vehicle and antenna

Abstract

Antenna (70), comprising: a dielectric (20, 23) with a first surface (21) and a second surface (22) on one side opposite the first surface; a first electrode (31) which is arranged on the side of the first surface of the dielectric or within the dielectric; a second electrode (32) which is arranged on one side of the second surface of the dielectric, such that at least part of the dielectric is arranged between the first electrode and the second electrode; an antenna element (71) arranged on the side of the first surface of the dielectric or within the dielectric and connected to the first electrode; and an amplifier (60) connected to the second electrode, wherein the antenna element is a conductor configured to receive at least one electromagnetic wave in a frequency band of an amplitude modulation (AM) transmission, and where, if a coupling capacitance exists between the first electrode and the second electrode with C c is designated as an antenna capacitance of the antenna element with C a is designated as an input capacitance of the amplifier with C i This is defined as a voltage value that is x decibels lower than a voltage value output by the second electrode when the coupling capacitance C is... c infinity, with v xdB is designated, and a received voltage value of the antenna element with v a is referred to a value of x 3.0 or less and the coupling capacity C c Formula 1 is sufficient: C c ≥ C i × C avxd B va C a − ( C a + C i ) × vxd B va

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present disclosure generally relates to a glass panel for a vehicle and an antenna. 2. Description of the state of the art

[0002] Conventionally, an antenna is known in which an antenna element and an internal electrode connected to the antenna element are arranged between two glass plates, and an external electrode is arranged opposite the internal electrode on a surface of the glass plate (see, for example, Japanese Unexamined Patent Application Publication No. 2011-114404). In the antenna, a reception signal from the antenna element arranged between the two glass plates is extracted from the external electrode by means of capacitance coupling between the internal electrode and the external electrode.

[0003] US 7 425 926 B2 describes a high-frequency wave glass antenna for a motor vehicle, wherein an antenna conductor and a feed electrode on the antenna conductor side, which is connected to the antenna conductor, are provided on a laminated glass pane for a motor vehicle.

[0004] US 9 755 299 B2 describes a window assembly for a vehicle having a transparent layer with a metal compound such that the transparent layer is electrically conductive. SUMMARY OF THE INVENTION[Technical Problem]

[0005] In the case of receiving electromagnetic waves in a frequency band of AM (Amplitude Modulation) transmission in which the frequency is relatively low by the antenna element between the two glass plates, and extracting a signal obtained by receiving from the external electrode by means of the capacitance coupling, a coupling loss of the capacitance coupling is large and sufficient reception sensitivity may not be obtained.

[0006] Accordingly, the disclosure of the present application provides a glass panel for a vehicle and an antenna capable of obtaining sufficient reception sensitivity in the case where a signal obtained by receiving an electromagnetic wave in the AM broadcast frequency band is extracted by means of capacitance coupling. [Solution to the problem]

[0007] The disclosure of the present application provides a glass pane for a vehicle, comprising: a glass plate; a dielectric having a first surface on a side facing the glass plate and a second surface on a side opposite the first surface; a first electrode disposed between the glass plate and the first surface of the dielectric; a second electrode disposed on the side of a second surface of the dielectric, such that the dielectric is disposed between the first electrode and the second electrode; and an antenna element arranged between the glass plate and the first surface of the dielectric and connected to the first electrode, wherein the antenna element receives at least one electromagnetic wave in a frequency band of an amplitude modulation (AM) transmission, and where, if a coupling capacitance between the first electrode and the second electrode is C c is called an antenna capacitance of the antenna element with C a is called, an input capacitance of an amplifier connected to the second electrode is C i a voltage value that is x decibels lower than a voltage value output by the second electrode when the coupling capacitance C c is infinite, with v xdB and a receiving voltage value of the antenna element with v a is referred to, the value of x is 3.0 or less and the coupling capacitance C c Formula 1 is sufficient: [Math 1A] Cc≥Ci×Ca×vxdBvaCa−(Ca+Ci)×vxdBva

[0008] Furthermore, the disclosure of the present application provides an antenna that a dielectric having a first surface and a second surface on a side opposite the first surface; a first electrode disposed on the side of the first surface of the dielectric or within the dielectric; a second electrode disposed on the side of the second surface of the dielectric, such that at least a portion of the dielectric is disposed between the first electrode and the second electrode; and an antenna element arranged on the side of the first surface of the dielectric or within the dielectric and connected to the first electrode, wherein the antenna element receives at least one electromagnetic wave in a frequency band of an amplitude modulation (AM) transmission, and where, if a coupling capacitance between the first electrode and the second electrode is C c is called an antenna capacitance of the antenna element with C a is called, an input capacitance of an amplifier connected to the second electrode is C i a voltage value that is x decibels lower than a voltage value output by the second electrode when the coupling capacitance C c is infinite, with v xdB and a receiving voltage value of the antenna element with v a is referred to, the value of x is 3.0 or less and the coupling capacitance C c Formula 1 is sufficient: [Math 1B] Cc≥Ci×CavxdBvaCa−(Ca+Ci)×vxdBva. [Effect of the invention]

[0009] According to the disclosure of the present invention, with the antenna or the glass panel for a vehicle, when a signal obtained by receiving an electromagnetic wave in the frequency band of AM broadcasting is extracted by means of capacitance coupling, sufficient reception sensitivity can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Further objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: Fig. 1 is an exploded perspective view showing an example of a structure of a glass panel for a vehicle according to a first embodiment; Fig. 2 is a cross-sectional view showing an example of a structure of a glass panel for a vehicle according to the first embodiment; Fig. 3 is a cross-sectional view showing an example of a structure of a glass panel for a vehicle according to a second embodiment; Fig. 4 is a cross-sectional view showing an example of a structure of a glass panel for a vehicle according to a third embodiment; Fig. 5 is a cross-sectional view showing an example of a structure of a glass panel for a vehicle according to a fourth embodiment; Fig. 6 is a cross-sectional view showing an example of a structure of a glass panel for a vehicle according to a fifth embodiment; Fig. 7 is a cross-sectional view showing an example of a structure of a glass panel for a vehicle according to a sixth embodiment; Fig. Figure 8 is a diagram showing an example of an equivalent circuit from an antenna to an amplifier; Fig. 9 is a diagram showing an example of a simulation result in which a relationship between an input capacitance of the amplifier and the coupling capacitance is measured, the coupling loss being 3.0 dB; Fig. 10 is a graph showing an example of a simulation result in which a relationship between the input capacitance of the amplifier and the coupling capacitance is measured, where the coupling loss is 2.0 dB; Fig. 11 is a graph showing an example of a simulation result in which a relationship between the input capacitance of the amplifier and the coupling capacitance is measured, with the coupling loss being 1.0 dB; Fig. 12 is a graph showing an example of a simulation result in which a relationship between the input capacitance of the amplifier and the coupling capacitance is measured, with the coupling loss being 0.5 dB; Fig. 13 is a diagram showing a mode in which two electrodes of a capacitance coupling portion overlap each other in a plan view; and Fig. 14 is a diagram showing an example of a simulation result for dimensions of respective parts for each shape of the electrode, wherein the coupling capacitance C c is 54 pF. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Embodiments for implementing the present invention will be described below with reference to drawings. It should be noted that in each embodiment, a direction such as parallel, a right angle, orthogonal, horizontal, vertical, up-down, right-left, or the like allows a deviation large enough so that the effect of the present invention is maintained. Moreover, the shape of a corner portion of an antenna element is not limited to a right angle, but may be arcuate and rounded. Furthermore, as a glass panel for a vehicle to which the present invention can be applied, a rear window installed in a rear part of a vehicle is preferable. However, the glass panel for a vehicle to which the present invention can be applied may, for example,a windshield installed in a front part of the vehicle, a side window installed in a side part of the vehicle, or a roof window installed in a roof part of the vehicle.

[0012] Furthermore, in each mode, a direction parallel to an X-axis (X-axis direction), a direction parallel to a Y-axis (Y-axis direction), and a direction parallel to a Z-axis (Z-axis direction) indicate the right-left direction of the glass plate (horizontal direction), the up-down direction of the glass plate (vertical direction), and a direction orthogonal to a surface of the glass plate (also called the perpendicular direction), respectively. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other.

[0013] The Fig. Fig. 1 is an exploded perspective view showing an example of a structure of a glass panel for a vehicle according to a first embodiment. Fig. 1, a positive side in the Z-axis direction represents a vehicle exterior, and a negative side in the Z-axis direction represents a vehicle interior. A glass pane 100 has a laminated glass structure in which a glass plate 10 arranged on the vehicle exterior and a glass plate 20 arranged on the vehicle interior are bonded together by means of an intermediate film 40. The Fig. 1 shows elements of the glass pane 100 separated in a direction perpendicular to a surface of the glass plate 10 or the glass plate 20.

[0014] The glass panel 100 includes the glass plate 10 disposed on the vehicle exterior; the glass plate 20 disposed on the vehicle interior; an inner electrode 31 and an antenna element 71 disposed within the laminated glass; and an outer electrode 32 disposed on a vehicle interior outer surface of the laminated glass.

[0015] Glass plate 10 and glass plate 20 are transparent plate-like dielectrics. One or both of glass plate 10 and glass plate 20 may be translucent. Glass plate 10 is an example of a first glass plate, and glass plate 20 is an example of a second glass plate.

[0016] The glass panel 10 has a panel surface 11 and a panel surface 12 on a side opposite to the panel surface 11 in the Z-axis direction. The panel surface 11 represents a surface of the glass panel 10 on the vehicle interior, and the panel surface 12 represents a surface of the glass panel 10 on the vehicle exterior. Specifically, the panel surface 12 corresponds to a vehicle exterior outer surface of the laminated glass.

[0017] The glass panel 20 has a panel surface 21 on a side facing the panel surface 11 of the glass panel 10 and a panel surface 22 on a side opposite the panel surface 21 in the Z-axis direction. The panel surface 21 represents a surface of the glass panel 20 on the vehicle exterior. The panel surface 22 represents a surface of the glass panel 20 on the vehicle interior. Specifically, the panel surface 22 corresponds to a vehicle interior exterior surface of the laminated glass.

[0018] The intermediate film 40 is a transparent or translucent dielectric material located between the glass plate 10 and the glass plate 20. The glass plate 10 and the glass plate 20 are connected to each other by the intermediate film 40. A material forming the intermediate film 40 includes, for example, a thermoplastic polyvinyl butyral. It should be noted that the dielectric constant of the intermediate film 40 is preferably 2.8 or more and 3.5 or less.

[0019] The internal electrode 31 is a conductor disposed between the plate surface 11 of the glass plate 10 and the plate surface 21 of the glass plate 20. The internal electrode 31 is an example of a first electrode. The internal electrode 31 according to the embodiment has a linear portion with a predetermined width, with a longitudinal direction aligned in the X-axis direction, which will be a vehicle width direction, and extends from one side edge of the glass plate 20 toward the other side edge along a top edge in the Y-axis direction of the glass plate 20. Furthermore, in the embodiment, the internal electrode 31 is formed to contact the plate surface 21 of the glass plate 20.

[0020] The external electrode 32 is a conductor arranged on the plate surface 22 side of the glass plate 20 such that the glass plate 20, which is a dielectric, is sandwiched between the internal electrode 31 and the external electrode 32. The external electrode 32 is an example of a second electrode. The external electrode 32 has a linear portion with a predetermined width with a longitudinal direction aligned in the X-axis direction, which will be the vehicle width direction, and extends from one side edge of the glass plate 20 toward the other side edge along the top edge in the Y-axis direction of the glass plate 20. Moreover, in the embodiment, the external electrode 32 is formed to contact the plate surface 22 of the glass plate 20.It should be noted that a mode of “extending along a top edge” may be a mode of contacting the top edge or a mode of being separate from the top edge.

[0021] The antenna element 71 is a conductor arranged between the plate surface 11 of the glass plate 10 and the plate surface 21 of the glass plate 20 and connected to the internal electrode 31. The antenna element 71 is designed, that is, a shape and a dimension thereof are determined, so that it receives at least one electromagnetic wave in a frequency band of amplitude modulation (AM) transmission (e.g., within a band of 500 kHz to 1800 kHz). However, as long as the antenna element 71 is designed to receive at least one electromagnetic wave in the frequency band of AM transmission (500 kHz to 1800 kHz), the shape and dimension thereof are not limited to those shown in the Fig. 1 are shown.

[0022] For example, the antenna element 71 may be configured to receive an electromagnetic wave of a medium frequency (MF) band, which includes the frequency band of AM (Amplitude Modulation) transmission. Alternatively, the antenna element 71 may be configured as a common antenna element that receives electromagnetic waves in both the MF band and the radio frequency (HF) band. Note that the MF band represents a frequency band of 300 kHz or more and 3 MHz or less. The HF band represents a frequency band of 3 MHz or more and 30 MHz or less, and is also referred to as the shortwave (SW) band.Furthermore, the antenna element 71 may be formed as a common antenna element that receives at least one of the electromagnetic wave in the MF band, an FM (Frequency Modulation) broadcast wave, a DAB (Digital Audio Broadcast) wave, and a terrestrial digital television broadcast wave.

[0023] The Fig. Fig. 1 is a diagram showing an example of a mode in which the antenna element 71 is formed on a conductive film 50 formed between the glass plate 10 and the glass plate 20. In the embodiment shown in Fig. Fig. As shown in FIG. 1, the conductive film 50 is a transparent or translucent conductor disposed between the intermediate film 40 and the glass plate 20. It may be, for example, a metal film such as an Ag film, a metal oxide film such as an ITO (indium tin oxide) film, a resin film containing conductive fine particles, or a stacked film in which a plurality of types of films are stacked. The conductive film 50 may be deposited on a resin film made of polyethylene terephthalate or the like by a vapor deposition method or the like.

[0024] In the embodiment shown in the Fig. 1, the conductive film 50 is removed around the conductor that will become the antenna element 71. Consequently, the conductor that will become the antenna element 71 remains as the conductive film 50, and the antenna element 71 is formed from the conductive film 50. That is, in the embodiment shown in Fig. 1, the conductive film 50 includes the antenna element 71. A grid part 56 is a region where the electrical resistance is increased by removing the conductive film 50 around the conductor, which becomes the antenna element 71.

[0025] For example, a heater 55 is formed on the conductive film 50. The heater 55 heats the glass panel 100 when a DC voltage is applied between the pair of bus bars 51 and 52, enabling snow melting, ice melting, and demisting through the glass panel 100. For example, the bus bar 51 is connected to a negative electrode of the DC power source via a flat cable 53, and the bus bar 52 is connected to a positive electrode of the DC power source via a flat cable 54. Alternatively, the conductive film 50 may be a heat-ray reflecting film that reflects heat rays entering from outside the vehicle. However, the use of the conductive film is not limited to this.

[0026] At least one antenna element other than the antenna element 71 may be formed on the conductive film 50. For example, Fig. 1 antenna elements 72 and 73 in addition to the antenna element 71. That is, in the embodiment shown in the Fig. As shown in Figure 1, the conductive film 50 includes antenna elements 72 and 73. The antenna elements 72 and 73 are each configured to receive an electromagnetic wave of a frequency band having a frequency higher than that of the RF band. The electromagnetic wave of the frequency band having a frequency higher than that of the RF band includes, for example, a terrestrial digital television broadcast wave, a DAB ("Digital Audio Broadcast") wave, or an FM (Frequency Modulation) broadcast wave.

[0027] In the embodiment shown in the Fig. 1, the antenna element 71 is connected to the internal electrode 31, the antenna element 72 is connected to the internal electrode 34, and the antenna element 73 is connected to the internal electrode 36. The internal electrodes 31, 34, and 36 may be portions formed from the conductive film 50. In this case, the conductive film 50 includes the internal electrodes 31, 34, and 36. At least one of the internal electrodes 31, 34, and 36 may be a portion formed from a conductor different from the conductive film 50. Accordingly, in the embodiment shown in Fig. 1, the antenna elements 71, 72, and 73 are each portions formed from the conductive film 50. However, at least one of the antenna elements 71, 72, and 73 may be a portion formed from a conductor different from the conductive film 50.

[0028] As the aforementioned conductor other than the conductive film 50, for example, at least one of the antenna elements 71, 72, and 73 may be formed by printing a paste containing a conductive metal (e.g., a silver paste) on a plate surface 21 of the glass plate 20 (or a plate surface 11 of the glass plate 10) and firing the paste. The same applies to any of the internal electrodes 31, 34, and 36. Alternatively, at least one of the antenna elements 71, 72, and 73 may be formed from a wire sandwiched between the glass plate 20 and the glass plate 10.

[0029] At least a portion of the internal electrode 31, to which the antenna element 71 is connected, is directed toward the external electrode 32 via the glass plate 20. A first input portion of an amplifier 60 is connected to the external electrode 32. A signal received at the antenna element 71 is then introduced into the first input portion of the amplifier 60 by means of capacitive coupling between the internal electrode 31 and the external electrode 32.

[0030] Accordingly, at least a portion of the internal electrode 34, to which the antenna element 72 is connected, is directed toward the external electrode 33 via the glass plate 20. A second input portion of the amplifier 60 is connected to the external electrode 33. A signal received at the antenna element 72 is then introduced into the second input portion of the amplifier 60 by means of capacitive coupling between the internal electrode 34 and the external electrode 33.

[0031] Accordingly, at least a portion of the internal electrode 36, to which the antenna element 73 is connected, is directed toward the external electrode 35 via the glass plate 20. An input portion of an amplifier 61 is connected to the external electrode 35. Then, a signal received at the antenna element 73 is introduced into the input portion of the amplifier 61 by means of capacitive coupling between the internal electrode 36 and the external electrode 35.

[0032] Furthermore, the glass panel 10 may be provided with a light-shielding film 13 that shields visible light. The light-shielding film 13 is disposed on an outer peripheral portion of the glass panel 10. The light-shielding film 13 overlaps with at least one of the internal electrode 31 and the external electrode 32 in the thickness direction of the glass panel 10. Specifically, the light-shielding film 13 comprises a ceramic film such as a black ceramic film. In the case where there is a part of the internal electrode, the external electrode, the antenna element, and the bus bar that overlaps with the light-shielding film 13 in a plan view of the glass panel 10, when the glass panel 100 is viewed from outside the vehicle, it is difficult to visually recognize the overlapping part. Consequently, the design characteristics of the glass panel 100 and the vehicle are improved.Specifically, since the internal electrode 31 and the external electrode 32 have relatively large areas, the light-shielding film 13 only needs to overlap with at least one of the internal electrode 31 and the external electrode 32, preferably overlaps with an electrode having a large area of ​​the internal electrode 31 and the external electrode 32, and more preferably overlaps with both the internal electrode 31 and the external electrode 32. The electrode having the larger area among the internal electrode 31 and the external electrode 32 only needs to have an area of ​​1675 mm. 2 or more, preferably 1682 mm 2 or more, more preferably 1705 mm 2 or more and even more preferably 1863 mm 2 or more.

[0033] The Fig. 2 to 7 show a variation of the lamination mode of the glass panel for a vehicle on which the antenna 70 according to the embodiment is arranged. Fig. 2 corresponds to a cross-sectional view of the structure shown in the Fig. 1 is shown.

[0034] In the Fig. 2 to 4, the antenna element 71 and the internal electrode 31 are arranged between the glass plate 10 and the glass plate 20. The internal electrode 31 and the external electrode 32 are arranged to overlap each other across the glass plate 20 in a plan view in the thickness direction of the glass plate 20 (Z-axis direction). Furthermore, the antenna element 71 and the internal electrode 31 contact an intermediate film 40 arranged between the glass plate 10 and the glass plate 20.

[0035] The value of a ratio of areas where the internal electrode 31 and the external electrode 32 overlap each other (the "ratio S" described later) is preferably large because the exposure (protrusion) of an electrode from the overlapping part can be made smaller, it becomes easier to cause the electrodes to overlap with the light-shielding film 13, and it becomes easier to reduce coupling loss. According to a result of simulations described later, under a condition where the electrodes have predetermined areas, the ratio of an area of ​​the overlapping part to a larger area of ​​areas of the internal electrode 31 and the external electrode 32 (the "ratio S" expressed as a percentage, where the larger area = 100%, and which will be described in detail later) is preferably 1.5% or more to reduce coupling loss.Furthermore, in addition to reducing the coupling loss between the internal electrode 31 and the external electrode 32 to reduce the exposure (protrusion) of the electrode as described above, the ratio of overlap (the “ratio S” described later) is preferably 10% or more, more preferably 40% or more, and even more preferably 70% or more.

[0036] The Fig. 2 is a diagram showing a structure in which the antenna element 71 and the internal electrode 31 are formed on a plate surface 21 of the glass plate 20. For example, the antenna element 71 and the internal electrode 31 are formed as a conductive film deposited on the plate surface 21 by performing a deposition process on the plate surface 21 of the glass plate 20.

[0037] The Fig. Fig. 3 is a diagram showing a structure in which the antenna element 71 and the internal electrode 31 are formed on a plate surface 11 of the glass plate 10. For example, the antenna element 71 and the internal electrode 31 are formed as a conductive film deposited on the plate surface 11 by performing a deposition process on the plate surface 11 of the glass plate 10. As shown in Fig. Fig. 3, the intermediate film 40 may be present between the internal electrode 31 and the external electrode 32 in addition to the glass 20.

[0038] The Fig. 4 is a diagram showing a structure in which the antenna element 71 and the internal electrode 31 are located between an intermediate film 41 and an intermediate film 42. The intermediate film 41 is an example of a first layer included in the intermediate film 40, and the intermediate film 42 is an example of a second layer included in the intermediate film 40. For example, the antenna element 71 and the internal electrode 31 are formed in a conductive film disposed between the intermediate film 41, which contacts the plate surface 11 of the glass plate 10, and the intermediate film 42, which contacts the plate surface 21 of the glass plate 20. As shown in FIG. Fig. 4, the intermediate film 42 may be present between the internal electrode 31 and the external electrode 32 in addition to the glass 20.

[0039] In addition, as stated in the Fig. 5 to 7, the glass panel for a vehicle according to the disclosure is not limited to laminated glass. In this case, a dielectric material provided between the internal electrode 31 and the external electrode 32 may not have the same size as the glass panel 10 in the thickness direction (Z-axis direction) in a plan view, and may be a dielectric substrate or a dielectric film having a size at least sufficient to form the external electrode 32.

[0040] In the Fig. 5 to 7, the antenna element 71 and the internal electrode 31 are arranged between the glass plate 10 and a dielectric substrate 23. The internal electrode 31 and the external electrode 32 are arranged to overlap in the thickness direction (Z-axis direction) of the dielectric substrate 23 in a plan view. The dielectric substrate 23 is, for example, a printed substrate made of a resin (e.g., a glass epoxy substrate in which a copper foil is adhered to an FR4 (Type 4 flame retardant)). The dielectric substrate 23 may be replaced by a dielectric film.

[0041] The Fig. 5 is a diagram showing an example of a structure in which the antenna element 71 and the internal electrode 31 are formed on the plate surface 11 of the glass plate 10. For example, the antenna element 71 and the internal electrode 31 are formed as a conductive film deposited on the plate surface 11 by performing a deposition process on the plate surface 11 of the glass plate 10. The external electrode 32 is provided on the plate surface 22 of the dielectric substrate 23. The dielectric substrate 23 is connected to the conductive film in which the antenna element 71 and the internal electrode 31 are formed by means of a connection layer 43, so that the external electrode 32 faces the internal electrode 31.

[0042] The Fig. 6 is a diagram showing another example of the structure in which the antenna element 71 and the internal electrode 31 are formed on the plate surface 11 of the glass plate 10. For example, the conductive film in which the antenna element 71 and the internal electrode 31 are formed is connected to the plate surface 11 by means of a connection layer 43a. The external electrode 32 is provided on the plate surface 22 of the dielectric substrate 23. The dielectric substrate 23 is connected to the conductive film in which the antenna element 71 and the internal electrode 31 are formed by means of a connection layer 43b, so that the external electrode 32 faces the internal electrode 31.

[0043] The Fig. 7 is a diagram showing an example of a structure in which the dielectric substrate 23, which is a component of the antenna 70, is bonded to the plate surface 11 of the glass plate 10 via the bonding layer 43. The antenna 70 is provided with the dielectric substrate 23 on which the antenna element 71, the internal electrode 31, and the external electrode 32 are formed. For example, the dielectric substrate 23 includes the plate surface 22 on which the external electrode 32 is formed such that at least a part of a dielectric portion is disposed between the plate surface 21 on which the antenna element 71 and the internal electrode 31 are formed and the internal electrode 31. At least one of the antenna element 71 and the internal electrode 31 may be provided in a form of being embedded within the dielectric substrate 23.

[0044] In this way, in the antenna 70 and the glass panel 100 according to the embodiment, at least a part of the internal electrode 31, to which the antenna element 71 is connected, is directed to the external electrode 32 via the dielectric (a glass plate or a dielectric substrate). Then, a signal obtained by receiving at the antenna element 71 is extracted from the external electrode 32 by means of a capacitive coupling between the internal electrode 31 and the external electrode 32. The signal extracted from the external electrode 32 is supplied to a (first) input part of an amplifier 60 (see the Fig. 1) by means of a conductive element connected to enable conduction to the external electrode 32. The conductive element comprises, in particular, a supply cable, such as an AV cable or a coaxial cable.

[0045] A coaxial cable is used as the feeder cable. A core wire of the coaxial cable (inner conductor) is connected to the external electrode 32, and an outer conductor of the coaxial cable is connected to a ground, such as a vehicle body. Furthermore, a connecting device may be used to connect the amplifier 60 to the external electrode 32. The connecting device is mounted, for example, on the external electrode 32. Alternatively, the amplifier 60 may be implemented in the connecting device.

[0046] In this way, the signal received at the antenna element 71 is extracted by the external electrode 32 by means of the capacitive coupling between the internal electrode 31 and the external electrode 32. The (first) input part of the amplifier 60 is directly or indirectly connected to the external electrode 32. The amplifier 60 amplifies the signal extracted by the external electrode 32 and outputs the amplified signal to a signal processing circuit (not shown) mounted on the vehicle.

[0047] An equivalent circuit diagram from the antenna element 71 to the amplifier 60 can be given by a circuit shown in the Fig. 8 is shown. In the Fig. 8, the coupling capacity between the internal electrode 31 and the external electrode 32 is C c the antenna capacitance of the antenna element 71 is denoted by C aand the input capacitance of the amplifier 60, which is connected to the external electrode 32, is denoted by C i In addition, an electrical voltage value x decibels lower than a voltage value V output from the external electrode 32 when the coupling capacitance is infinite is denoted by v xdB and a receiving voltage value of the antenna element 71 is denoted by v a It should be noted that x is 3.0 or less. If the coupling capacitance C c satisfying the following formula 1, the coupling loss of the coupling capacitance between the internal electrode 31 and the external electrode 32 x decibels or less. [Math 1C] Cc≥Ci×Ca×vxdBvaCa−(Ca+Ci)×vxdBva

[0048] C a represents the capacitance between the antenna element 71 and the ground, such as a vehicle body. C irepresents the input capacitance between the input part of the amplifier 60 and the ground, such as a vehicle body. "If the coupling capacitance C c "Infinite" means that the internal electrode 31 and the external electrode 32 are directly connected by a conductor without capacitive coupling. That is, this represents a state where the coupling loss of the coupling capacitance between the internal electrode 31 and the external electrode 32 is zero. Hereinafter, "the coupling loss of the coupling capacitance between the internal electrode 31 and the external electrode 32" is also simply referred to as "coupling loss."

[0049] The state in which the coupling capacitance C c is infinite, is an ideal state in which coupling loss is absent in capacitive coupling. Since the coupling loss of the coupling capacitance is smaller when the coupling capacitance C clarger, a reduction of a divided voltage applied to the input capacitance C i applied (voltage input to amplifier 60) due to coupling loss. Consequently, if the coupling capacitance C c is set to satisfy Formula 1, a decrease in the voltage input to the amplifier 60 due to the coupling loss can be prevented. Consequently, in the case of extracting, by means of capacitive coupling, a signal obtained by receiving an electromagnetic wave in the AM broadcast frequency band, an electric voltage input to the amplifier 60 is ensured, and sufficient reception sensitivity is maintained in the amplifier 60. It should be noted that, regarding the coupling loss of x decibels, the value of x is preferably 2.0 or less, more preferably 1.0 or less, and even more preferably 0.5 or less.

[0050] The Fig. Figure 9 is a diagram showing an example of a simulation result in which a relationship between an input capacitance C i of the amplifier 60 and the coupling capacitance C c is measured, with a coupling loss of 3.0 dB. Fig. 10 is a diagram showing an example of a simulation result in which a relationship between an input capacitance C of the amplifier 60 and the coupling capacitance C c is measured, with a coupling loss of 2.0 dB. Fig. 11 is a diagram showing an example of a simulation result in which a relationship between an input capacitance C i of the amplifier 60 and the coupling capacitance C c is measured, with a coupling loss of 1.0 dB. Fig. 12 is a diagram showing an example of a simulation result in which a relationship between an input capacitance C i of the amplifier 60 and the coupling capacitance C c The coupling loss is 0.5 dB. The curves shown in the Fig. 9 to 12 are given by the following formula 2. [Math 1C] Cc=Ci×CavxdBvaCa−(Ca+Ci)×vxdBva

[0051] The curve that is in the Fig. 9 shows the case where x = 3.0 for v xdB is the curve that is in the Fig. 10 indicates the case where x = 2.0 for v xdB is the curve that is in the Fig. 11 indicates the case where x = 1.0 for v xdB and the curve that is in the Fig. 12 indicates the case where x = 0.5 for v xdBSince an antenna capacitance of an antenna element for receiving an AM transmission wave is typically in a range of 20 pF to 80 pF, the antenna capacitance C a in the Fig. 9 to 12 are set to the minimum value of the range (i.e., 20 pF). Furthermore, the input capacitance of an amplifier typically ranges from 10 pF to 80 pF.

[0052] Consequently, as stated in the Fig. 9, for example in the case of using an amplifier 60 with an input capacitance C i of 10 pF by designing the antenna in such a way that the coupling capacitance C c 16.2 pF or more, the coupling loss can be set to 3.0 dB or less, and the receiving sensitivity of the amplifier 60 can be increased. In addition, as described in the Fig. 10, for example in the case of using an amplifier 60 with an input capacitance Ci of 10 pF by designing the antenna in such a way that the coupling capacitance C c 25.7 pF or more, the coupling loss can be set to 2.0 dB or less, and the receiving sensitivity of the amplifier 60 can be increased. In addition, as described in the Fig. 11, for example in the case of using an amplifier 60 with an input capacitance C i of 10 pF by designing the antenna in such a way that the coupling capacitance C c 54.6 pF or more, the coupling loss can be set to 1.0 dB or less, and the receiving sensitivity of the amplifier 60 can be increased. In addition, as described in the Fig. 12, for example in the case of using an amplifier 60 with an input capacitance C i of 10 pF by designing the antenna in such a way that the coupling capacitance C c112.5 pF or more, the coupling loss can be set to 0.5 dB or less, and the receiving sensitivity of the amplifier 60 can be increased.

[0053] In a plan view in the thickness direction of the dielectric, the coupling capacitance C c larger as an area where the internal electrode 31 and the external electrode 32 overlap each other (hereinafter also referred to as "overlap area A") is larger. Therefore, the overlap area A is preferably larger to reduce the coupling loss. However, if the upper limit of the overlap area A is calculated taking into account the upper limit of an area of ​​the glass plate or the dielectric substrate, the upper limit of the coupling capacitance C c about 3500 pF.

[0054] The Fig. Figure 13 is a diagram showing a structure in which two electrodes of the capacitive coupling part overlap each other in plan view. Fig. 13, one of the internal electrode 31 and the external electrode 32 having a larger area is arranged as electrode 1, and one having a smaller area is arranged as electrode 2. The Fig. 14 is a diagram showing an example of a simulation result for dimensions of respective parts for each shape of the electrode, where the coupling capacitance C c 54 pF. If the coupling capacitance C c 54 pF or more, as described above, the coupling loss can be adjusted to about 1 dB or less. Fig. Figure 14 shows three cases: Electrodes 1 and 2, which are in the Fig.13 have rectangular shapes (sample #1 and sample #2) and square shapes (sample #3). As assumptions for the simulation, the dielectric between electrode 1 and electrode 2 had a thickness of 1.6 mm and a dielectric constant of 8.0. Electrode 2 had a shape in which an outer edge of electrode 2 was shifted inward from an outer edge of electrode 1 by 3 mm, taking into account a variation in the sizes of electrodes 1 and 2 during manufacturing. The maximum length L1 of electrode 1 was set to 1600 mm taking into account the maximum width of a rear window of the vehicle in the vehicle width direction. The maximum width H1 of electrode 1 was set to 50 mm taking into account the maximum width of the light-shielding film 13. The area of ​​electrode 1 is denoted by S1, and the area of ​​electrode 2 is denoted by S2.

[0055] If the maximum area of ​​electrode 1 (maximum value of area S1) is 80000 mm 2 which is the product of 1600 mm (length) and 50 mm (width), the overlap area A, when the coupling capacity C c 16.2 pF or more than 366 mm 2 or more. Consequently, the proportion S of the overlap area A for electrode 1 only needs to be 0.46% or more. This means that in order to reduce the coupling loss to 3.0 dB or less, the overlap area A is preferably 366 mm 2 or more, or the proportion S of the overlap area A is preferably 0.46% or more for the electrode 1. In addition, in order to bring the coupling loss to 2.0 dB or less, the overlap area A according to the simulation is preferably 582 mm 2or more, or the proportion S of the overlap area A is preferably 0.73% or more for electrode 1. To bring the coupling loss to 1.0 dB or less, the overlap area A according to the simulation is preferably 1220 mm 2 or more, or the proportion S of the overlap area A is preferably 1.5% or more for the electrode 1. In addition, in order to bring the coupling loss to 0.5 dB or less, the overlap area A according to the simulation is preferably 2520 mm 2 or more, or the proportion S of the overlap area A for the electrode 1 is preferably 3.1% or more.

[0056] If the overlap area A is 366 mm 2and the width H2 of the electrode 2 is 10 mm, the length L2 of the electrode 2 is 36.6 mm. Therefore, in order to bring the coupling loss to 3.0 dB or less, the electrode 2 preferably has a length L2 in the vehicle width direction of 36.6 mm or more. In addition, when the overlap area A is 582 mm 2 and the width H2 of the electrode 2 is 10 mm, the length L2 of the electrode 2 is 58.2 mm. Therefore, in order to bring the coupling loss to 2.0 dB or less, the electrode 2 preferably has a length L2 in the vehicle width direction of 58.2 mm or more. In addition, when the overlap area A is 1220 mm 2 and the width H2 of the electrode 2 is 50 mm, the length L2 of the electrode 2 is 24.4 mm. Therefore, in order to reduce the coupling loss to 1.0 dB or less, the electrode 2 preferably has a length L2 in the vehicle width direction of 24.4 mm or more.

[0057] As described above, the embodiments have described the glass panel for a vehicle and the antenna. The present invention is not limited to the embodiments. Various variations and improvements, such as combining / replacing with / part or all of another embodiment, can be made without departing from the scope of the present invention.

[0058] This application is based on and claims priority from Japanese priority applications No. 2018-022010, filed on February 9, 2018, and No. 2018-216002, filed on November 16, 2018, the entire contents of which are incorporated herein by reference. LIST OF REFERENCE SYMBOLS 10 Glass plate (example of a first glass plate) 13 Light-shielding film 20 Glass plate (example of a second glass plate or a dielectric) 21 Plate surface (example of a first surface) 22 Plate surface (example of a second surface) 23 Dielectric substrate (example of a dielectric) 31 Internal electrode (example of a first electrode) 32 External electrode (example of a second electrode) 40 Intermediate film 41 Intermediate film (example of a first layer) 42 Intermediate film (example of a second layer) 43 Connection layer 50 Lead Film 51,52 busbar 55 Heating device 56 Grid part 60,61 amplifiers 70 antenna 71,72,73 antenna element 100 glass panes

Claims

[1] Antenna (70), comprising: a dielectric (20, 23) having a first surface (21) and a second surface (22) on a side opposite the first surface; a first electrode (31) arranged on the side of the first surface of the dielectric or within the dielectric; a second electrode (32) disposed on one side of the second surface of the dielectric such that at least a portion of the dielectric is disposed between the first electrode and the second electrode; an antenna element (71) arranged on the side of the first surface of the dielectric or within the dielectric and connected to the first electrode; and an amplifier (60) connected to the second electrode, wherein the antenna element is a conductor configured to receive at least one electromagnetic wave in a frequency band of an amplitude modulation (AM) transmission, and where, if a coupling capacitance between the first electrode and the second electrode is C c is called an antenna capacitance of the antenna element with C a is called an input capacitance of the amplifier with C i a voltage value that is x decibels lower than a voltage value output by the second electrode when the coupling capacitance C c is infinite, with v xdB and a receiving voltage value of the antenna element with v a is referred to, a value of x is 3.0 or less and the coupling capacitance C c Formula 1 is sufficient: Cc≥Ci×CavxdBvaCa−(Ca+Ci)×vxdBva [2] The antenna (70) according to claim 1, wherein a ratio of an area of ​​a part where the first electrode (31) and the second electrode (32) overlap each other in a plan view in the thickness direction of the dielectric to a larger area of ​​an area of ​​the first electrode and an area of ​​the second electrode is 0.46% or more. [3] Antenna (70) according to claim 2, wherein the larger area of ​​the area of ​​the first electrode (31) and the area of ​​the second electrode (32) is 1675 mm 2 or more. [4] The antenna (70) according to any one of claims 1 or 3, wherein the area of ​​the part where the first electrode (31) and the second electrode (32) overlap each other is 366 mm 2 or more. [5] The antenna (70) of any one of claims 1 to 4, wherein the value of x is 1.0 or less. [6] The antenna (70) of claim 5, wherein the value of x is 0.5 or less. [7] Antenna (70) according to one of claims 1 to 6, wherein the input capacitance of the amplifier (60) connected to the second electrode is C i , 10 pF or more and 80 pF or less. [8] Antenna (70) according to one of claims 1 to 7, wherein the antenna capacitance of the antenna element (71), C a , 20 pF or more and 80 pF or less. [9] Glass pane (100) for a vehicle, comprising: an antenna according to one of claims 1 to 8; a glass plate (10); wherein the first surface (21) of the dielectric (20, 23) is on a side facing the glass plate (10); wherein the first electrode (31) is arranged between the glass plate and the first surface of the dielectric; wherein the second electrode (32) is arranged on one side of the second surface of the dielectric, so that the dielectric is arranged between the first electrode and the second electrode; and wherein the antenna element (71) is arranged between the glass plate and the first surface of the dielectric and is connected to the first electrode. [10] A glass panel (100) for a vehicle according to claim 9, wherein the glass panel (10) comprises a light-shielding film (13) overlapping with at least one of the first electrode (31) and the second electrode (32) in the thickness direction of the glass panel. [11] Glass pane (100) for a vehicle according to one of claims 9 or 10, wherein the glass plate (10) is a first glass plate and the dielectric (20, 23) is a second glass plate (20), and wherein the glass sheet (100) has a laminated glass structure in which the first glass plate and the second glass plate are bonded to each other by means of an intermediate film (40). [12] Glass pane (100) for a vehicle according to claim 11, wherein the first electrode (31) contacts the intermediate film (40). [13] Glass pane (100) for a vehicle according to claim 11 or 12, wherein the intermediate film (40) comprises a first layer (41) and a second layer (42), and wherein the first electrode (31) is located between the first layer and the second layer. [14] A glass panel (100) for a vehicle according to any one of claims 9 to 13, wherein at least one of the first electrode (31) and the second electrode (32) comprises linear portions having a longitudinal direction aligned in a direction that will be a width direction of a vehicle. [15] The glass panel (100) for a vehicle according to any one of claims 9 to 14, wherein one of the first electrode (31) and the second electrode (32), an area of ​​the electrode being a smaller area of ​​an area of ​​the first electrode and an area of ​​the second electrode, has a length of 24.4 mm or more in a direction which will be the width direction of a vehicle.

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