EP3570370A1

EP3570370A1 - Window glass

Info

Publication number: EP3570370A1
Application number: EP18739438.2A
Authority: EP
Inventors: Kosuke Tanaka; Tatsumi Tokuda
Original assignee: Nippon Sheet Glass Co Ltd
Current assignee: Nippon Sheet Glass Co Ltd
Priority date: 2017-01-11
Filing date: 2018-01-11
Publication date: 2019-11-20
Anticipated expiration: 2038-01-11
Also published as: JP2018113587A; CN110168805A; JP6868396B2; WO2018131647A1; EP3570370A4; EP3570370B1

Abstract

A window glass according to the present invention includes a glass plate, a defogger formed on the glass plate and having a pair of bus bars and a plurality of horizontal heating wires that join the pair of bus bars, and an antenna formed on the glass plate, the antenna including a first power supply part, a first antenna element extending from the first power supply part, a second power supply part, and a second antenna element extending from the second power supply part, the antenna being configured to receive radio waves of a frequency range of a first media, using the first antenna element and the second antenna element, and the first antenna element and the second antenna element both being capacitively coupled to the defogger.

Description

Technical Field

The present invention relates to a window glass and a backdoor provided with the same.

Background Art

Devices such as defoggers for removing condensation or ice and antennas for receiving predetermined radio waves may be provided on the surface of a window glass for vehicles (particularly the rear glass) that is to be attached to an automobile. Defoggers have a plurality of horizontal heating wires that extend horizontally across the entirety of the window glass. Also, as antennas, DAB antenna elements for receiving DAB (Digital Audio Broadcasting; hereinafter "DAB") broadcasts may be used, for example, and Patent Literature 1 proposes a window glass for vehicles on which a DAB antenna element is provided together with a defogger. This DAB antenna element is capacitively coupled to the defogger, and improves reception performance, by also utilizing the defogger as part of the antenna.

Citation List

Patent Literature

Patent Literature 1: WO 2016/190064

Summary of Invention

Technical Problem

However, there is room for improvement in reception performance that utilizes a defogger, and further improvement in reception performance is desired. Such problems are common to reception of not only DAB but also other media. The present invention has been made in order to solve the above problem, and an object thereof is to provide a window glass and a backdoor provided with the same that are able to further improve reception performance using a defogger and an antenna.

Solution to Problem

A window glass according to the present invention includes a glass plate, a defogger formed on the glass plate and having a pair of bus bars and a plurality of horizontal heating wires that join the pair of bus bars, and an antenna formed on the glass plate, the antenna including a first power supply part, a first antenna element extending from the first power supply part, a second power supply part, and a second antenna element extending from the second power supply part, the antenna being configured to receive a radio wave of a frequency range of a first media, using the first antenna element and the second antenna element, and the first antenna element and the second antenna element both being capacitively coupled to the defogger.
Note that "horizontal" in the present invention is used to mean a direction generally parallel to the installation surface of the vehicle. Accordingly, "horizontal" does not necessarily indicate a strict direction, and, for example, what is referred to as "horizontal" may be slightly inclined rather than being strictly parallel to the installation surface of the vehicle. The meaning of "horizontal" is the same throughout this specification.
In the above window glass, the first antenna element and the second antenna element can be respectively capacitively coupled in different regions of the defogger.
In the above window glass, the defogger can have an auxiliary element extending from one of the horizontal heating wires, and at least one of the first antenna element and the second antenna element can be capacitively coupled to the auxiliary element.
In the above window glass, a configuration can be adopted in which the auxiliary element extends from an uppermost or lowermost horizontal heating wire, among the horizontal heating wires, the defogger includes a first vertical element that intersects a plurality of the horizontal heating wires including at least the uppermost or lowermost horizontal heating wire to which the auxiliary element is connected, and a distance between the first vertical element and the auxiliary element is 100 mm or less.
In the above window glass, a configuration can be adopted in which the defogger includes a second vertical element disposed on the first power supply part or second power supply part side with respect to the first vertical element and intersecting a plurality of the horizontal heating wires, and L≤α·λ/2 is satisfied, where L is a distance between the first vertical element and the second vertical element, α is a shortening coefficient of wavelength of the glass plate, and λ is a shortest wavelength corresponding to a frequency range of the first media.
In the above window glass, the second power supply part can be grounded.
In the above window glass, a configuration can be adopted in which the first media is DAB.
A backdoor according to the present invention includes the window glass according to any of the above, and a resin cover member having a window opening part to which the window glass is attached, and supporting the window glass.

Advantageous Effects of Invention

With the window glass according to the present invention, reception performance can be further improved.

Brief Description of Drawings

FIG. 1 is a front view of a rear glass of an automobile in which an embodiment of a vehicle window glass according to the present invention is mounted.
FIG. 2 is a front view showing another example of the window glass according to FIG. 1.
FIG. 3 is a diagram showing a model of a window glass according to working example 1.
FIG. 4 is a diagram showing a model of a window glass according to comparative example 1.
FIG. 5 is a diagram showing a model of a window glass according to comparative example 2.
FIG. 6 is a graph showing the reception performances of working example 1 and comparative examples 1 and 2.
FIG. 7 is a diagram showing a model of a window glass according to working example 2.
FIG. 8 is a graph showing the reception performances of working examples 1 and 2 and comparative example 1.
FIG. 9 is a graph showing the reception performances of working examples 2 to 8 and comparative example 1.
FIG. 10 is a diagram showing a model of a window glass according to working example 9.
FIG. 11 is a diagram showing a model of a window glass according to comparative example 3.
FIG. 12 is a graph showing the reception performances of working examples 1 and 9 and comparative example 3.
FIG. 13 is a plan view showing a window glass according to working example 10.
FIG. 14 is a graph showing the reception performances of working examples 9 and 10 and comparative example 3.
FIG. 15 is a diagram showing a model of a window glass according to working example 11.
FIG. 16 is a graph showing the reception performances of working examples 10 and 11 and comparative example 3.
FIG. 17 is a graph showing the reception performances of working examples 10 and 12 to 14 and comparative example 3.
FIG. 18 is a diagram showing a model of a window glass according to working example 15.
FIG. 19 is a graph showing the reception performances of working examples 9, 10 and 15 and comparative example 3.
FIG. 20 is a diagram showing a model of a window glass according to working example 16.
FIG. 21 is a diagram showing a model of a window glass according to comparative example 4.
FIG. 22 is a graph showing the reception performances of working examples 10 and 16 and comparative example 4.
FIG. 23 is a graph showing the reception performances of working examples 16 and 17 and comparative example 4.

Description of Embodiments

Hereinafter, an embodiment of a vehicle window glass according to the present invention will be described, with reference to the drawings. FIG. 1 is a front view of a rear glass of an automobile to which the vehicle window glass according to the present embodiment is applied. Note that, hereinafter, for convenience of description, the up-down direction in FIG. 1 may be referred to as the up-down direction or the vertical direction, and the left-right direction in FIG. 1 may be referred to as the left-right direction or the horizontal direction, based on the orientation of FIG. 1, but this orientation is not intended to limit the invention.

1. Vehicle Window Glass

As shown in FIG. 1, with the vehicle window glass according to the present embodiment, a defogger 2 and a DAB (Digital Audio Broadcast) antenna 3 are mounted on a glass plate 1. Hereinafter, these members will be described in order.

1-1. Glass Plate

A well-known glass plate for automobiles can be utilized for the glass plate 1. For example, heat absorbing glass, common clear glass, common green glass or UV green glass may be utilized as the glass plate 1. Such a glass plate 1 needs, however, to realize a visible light transmittance in line with safety standards of the country in which the automobile will be used. For example, solar absorbance, visible light transmittance and the like can be adjusted to meet safety standards. Hereinafter, an example of the composition of clear glass and an example of the composition of heat absorbing glass will be shown.

Clear Glass

SiO₂: 70 to 73 mass%
Al₂O₃: 0.6 to 2.4 mass%
CaO: 7 to 12 mass%
MgO: 1.0 to 4.5 mass%
R₂O: 13 to 15 mass% (R is an alkaline metal)
Total iron oxide in terms of Fe₂O (T-Fe₂O₃): 0.08 to 0.14 mass%

Heat Absorbing Glass

The composition of heat absorbing glass can, for example, be given as a composition, based on the composition of clear glass, including total iron oxide in terms of Fe₂O₃ (T-Fe₂O₃) at a ratio of 0.4 to 1.3 mass%, CeO₂ at a ratio of 0 to 2 mass%, and TiO₂ at a ratio of 0 to 0.5 mass%, and in which the skeletal component (mainly SiO₂ or Al₂O₃) of the glass is reduced by an amount equivalent to the increase in T-Fe₂O₃, CeO₂ and TiO₂.
Note that the type of glass plate 1 is not limited to clear glass or heat absorbing glass, and is selectable as appropriate according to the embodiment.
Also, such a glass plate 1, apart from being constituted by a single glass plate, may be a laminated glass in which an intermediate film such as a resin film is sandwiched by a plurality of plates of glass. The thickness of the glass plate 1, for both a single glass plate or a laminated glass (total thickness), is preferably 2 to 5 mm, more preferably 2.5 to 4.5 mm, and especially preferably 3 to 4 mm, for example. Note that the shortening coefficient of wavelength α of a glass plate also changes depending on factors such as the thickness of the glass plate, being approximately 0.7 in the case where a defogger, an antenna element and the like are formed on a single glass plate, and approximately 0.5 in the case of a laminated glass in which an intermediate film is sandwiched by two glass plates, for example, and more specifically, changes in the following manner, depending on the frequency of the broadcast waves to be received and the thickness of the glass plate. The shortening coefficients of wavelength in the following Table 1 are, however, given as examples, and can also change depending on other conditions. Table 1

Thickness [mm] 100 MHz 200 MHz 300 MHz

2 0.78 0.71 0.67

3 0.74 0.67 0.62

4 0.71 0.64 0.59

1-2. defogger

Next, the defogger 2 will be described. As shown in FIG. 1, the defogger 2 is disposed in the vicinity of the middle of the glass plate 1 in the vertical direction, and is formed so as to extend across the entirety of the glass plate 1 in the left-right direction. Specifically, this defogger 2 includes a pair of bus bars 21a and 21b for power supply that extend in the up-down direction along both side edges of the glass plate 1. Here, for convenience of description, the bus bar on the left side will be referred to as a first bus bar 21a and the bus bar on the right side will be referred to as a second bus bar 21b. Between both bus bars 21a and 21b, a plurality of horizontal elements (horizontal heating wires) 22 are disposed in parallel at a predetermined interval, and heat for defogging is produced by power supply from the bus bars 21a and 21b. Also, three vertical elements 41 to 43 that extend in the up-down direction are formed in this defogger 2. Here, for convenience of description, the vertical element on the left side will be referred to as a left vertical element 41, the vertical element in the middle will be referred to as a middle vertical element 42, and the vertical element on the right side will be referred to as a right vertical element 43. These vertical elements 41 to 43 extend so as to link the horizontal element that is uppermost (hereinafter, uppermost horizontal element) 221 and the horizontal element that is lowermost (hereinafter, lowermost horizontal element) 222, so as to intersect all the horizontal elements 22.
Also, an auxiliary element 5 that extends from an intersection portion 25 of the lowermost horizontal element 222 and the middle vertical element 42 is provided in this defogger 2. More specifically, this auxiliary element 5 is formed in an L-shape having a first region 51 that extends downward from the above intersection portion 25 and a second region 52 that extends horizontally toward the left side from the lower end of this first region 51. The position of this auxiliary element 5 is, however, adjustable, and the upper end of the first region 51 can also be disposed at any position of the lowermost horizontal element 222 in the horizontal direction. The auxiliary element 5 is, however, preferably connect to an intersection portion with one of the vertical elements 41 to 43. When the intersection portion with the middle vertical element 42 is the origin, the auxiliary element 5 is preferably connected within a range of 150 mm toward the right side and 150 mm toward the left side, and more preferably within a range of 100 mm toward the right side and toward 100 mm toward the left side, centered on this origin.
Incidentally, standing waves constantly occur in the defogger 2, and the wavelength band of these standing waves depends on the length of the horizontal elements 22 of the defogger 2. Also, in the case where the DAB antenna 3 discussed later is disposed near the defogger 2 and this DAB antenna 3 is capacitively coupled to the defogger 2, the inventor found that, if the length of the horizontal elements 22 is half the wavelength λ of broadcast waves that are received by the antenna 3, or in other words, an integer multiple of λ/2, the antenna 3 is affected by the standing waves that occur in the defogger 2 (note that λ as referred to here is obtained by multiplying the wavelength by the shortening coefficient of wavelength of the glass plate). That is, if radio waves received with the defogger 2 are excited in the defogger 2 as standing waves of half the frequency band of the DAB antenna 3, energy of an amount equal to the resultant excitation energy is supplied from the defogger 2 to the DAB antenna 3 through capacitive coupling, and the radio waves of the frequency band of the DAB antenna 3 are trapped in the defogger 2. As a result, it was found that the reception sensitivity of the DAB antenna 3 decreases. It was also noted, however, that in the case where the horizontal elements 22 are divided by the vertical elements 41 to 43, as in the present embodiment, the influence of the standing waves can be controlled depending on the length of the divided horizontal elements 22, or in other words, the intervals of the bus bars 21a and 21b and the vertical elements 41 to 43, and the interval between the adjacent vertical elements 41 to 43, and, as a result, the decrease in the reception sensitivity of the DAB antenna 3 can be suppressed.
Also, when standing waves occur and an integer multiple of the frequency thereof corresponds to the DAB frequency band, reception performance as an antenna decreases and the DAB antenna 3 no longer functions adequately. However, as mentioned above, a decrease in reception performance can be prevented by adjusting the intervals of the bus bars 21a and 21b and the vertical elements 41 to 43 and the interval between the adjacent vertical elements 41 to 43 to control the frequency of the standing waves. Hereinafter, this point will be considered.
Here, the interval of the first bus bar 21a and the left vertical element 41 in the horizontal direction will be referred to as a first interval P1, the interval of the left vertical element 41 and the middle vertical element 42 in the horizontal direction will be referred to as a second interval P2, the interval of the middle vertical element 42 and the right vertical element 43 in the horizontal direction will be referred to as a third interval P3, and the interval of the right vertical element 43 and the second bus bar 21b in the horizontal direction will be referred to as a fourth interval P4. Note that these intervals P are the intervals of lower end parts thereof.
The vertical elements 41 to 43 are preferably disposed so as to satisfy any of the following equations (1) and (2), where Pmin is the smallest of these four intervals, λ₁ to λ₂ are the wavelength bands of DAB broadcast waves that are received by the DAB antenna 3, and α is the shortening coefficient of wavelength of the abovementioned glass plate 1. $Pmin < α \cdot λ_{1} / 2$
$P 2 < α \cdot λ_{1} / 2$
Note that the wavelength band corresponding to 170 to 240 MHz, which is the frequency range of DAB Band III, will be approximately 813 to 1147 mm (= αλ₁ to αλ₂) when the shortening coefficient of wavelength of a typical glass plate is taken into consideration (where α = 0.65).
Equation (1) shows that the smallest interval Pmin, among the intervals of the divided horizontal elements 22, is smaller than α·λ₁/2. Accordingly, when at least one interval is smaller than α·λ₁/2, among the plurality of intervals, the decrease in the reception performance of the DAB antenna due to standing waves is suppressed.
Also, equation (2) shows that P2, which is the interval of the middle vertical element 42 to which the auxiliary element 5 is connected and the left vertical element 41 disposed on the DAB antenna 3 side thereof is smaller than α·λ₁/2. As will be discussed later, since the auxiliary element 5 greatly influences the reception performance, adjustment of the interval P2 of the middle vertical element 42 that is connected thereto and the left vertical element 41 on the DAB antenna 3 side thereof contributes to suppressing the decrease in the reception performance of the DAB antenna 3.

1-3. DAB Antenna

Next, the DAB antenna 3 will be described. The DAB antenna 3 according to the present embodiment is disposed downward of the defogger 2 in the glass plate 1. Specifically, the DAB antenna 3 is provided with a first power supply part 31 disposed between the first bus bar 21a and the left vertical element 41, and a second power supply part 32 disposed on the right side of this first power supply part 31. Furthermore, this DAB antenna 3 is provided with a first antenna element 33 that extends toward the right side from the first power supply part 31, and a second antenna element 34 that extends toward the right side from the second power supply part 32.
The first power supply part 31 and the second power supply part 32 are connected to a DAB tuner (illustration omitted), and can be connected by a coaxial cable (illustration omitted), for example. In this case, the first power supply part 31 is connected to a signal wire (core wire) of the coaxial cable, and the second power supply part 32 is connected to a grounding wire (external conductor) of the coaxial cable. This configuration can, however, also be reversed. That is, the first power supply part 31 can be connected to the grounding wire, and the second power supply part 32 can be connected to the core wire.
The first antenna element 33 extends linearly along the lowermost horizontal element 222 of the defogger 2, and is capacitively coupled to the lowermost horizontal element 222. On the other hand, the second antenna element 34 extends, on the upper side of the second region 52 of the auxiliary element 5, along this second region 52, and is capacitively coupled to the auxiliary element 5. A distance S1 between the first antenna element 33 and the lowermost horizontal element 222 and a distance S2 between the second antenna element 34 and the second region 52 of the auxiliary element 5, in order to perform capacitive coupling, are each preferably 5 to 50 mm, and more preferably 5 to 20 mm, respectively. Also, a distance S3 between the first power supply part 31 and the second power supply part 32 is preferably 5 to 50 mm, for example.
DAB broadcast waves are received by the first antenna element 33 and the second antenna element 34 constituted as described above.

1-4. Material

A defogger 2 and DAB antenna 3 such as described above can be formed by laminating a conductive material having conductivity on the surface of the glass plate 1, such that a predetermined linear pattern is formed. Such a material need only have conductivity, and is selectable as appropriate according to the embodiment, with silver, gold, platinum and the like given as examples. These members can be formed by, for example, printing and baking a conductive silver paste containing silver powder, glass frit and the like on the surface of the glass plate 1.

1-5. Manufacturing Method

Next, a manufacturing method of the window glass according to the present embodiment will be described. The glass plate 1 of the window glass according to the present embodiment can be shaped by methods such as a press-molding method for shaping the glass plate 1 with a press or a self-weight bending method for bending the glass plate 1 under its own weight.
Here, at the time of shaping the glass plate 1 with these respective methods, the glass plate 1 is heated to the vicinity of the softening point in a heating furnace. Before being placed in this heating furnace, the glass plate 1 is flat in shape, and a paste for the various materials mentioned above, such as a silver paste, for example, is printed on the surface of this glass plate 1. Then, by placing the glass plate 1 in the heating furnace, the silver paste printed on the glass plate 1 is baked together with shaping the glass plate 1, enabling the defogger 2 and the DAB antenna 3 to be formed.

2. Features

Although the DAB antenna shown in the conventional example also has a first power supply part and a second power supply part, these power supply parts are normally positioned close together. However, given the problem of space and the fact that the elements need to be of a length suitable for the media, in the conventional example, only the first antenna element is capacitively coupled. That is, the technical idea of capacitively coupling both the first antenna element and the second antenna element did not arise. In particular, the rear glass is typically attached to the metal vehicle body or door, and performance can be adequately secured when the grounding wire side is connected (including the case of being capacitively coupled, besides being directly connected; this similarly applies below) to the metal vehicle body or the like, the technical idea of capacitively coupling both the first and second antenna elements to the defogger did not arise.
In contrast, in the present embodiment, both the first antenna element 33 and the second antenna element 34 constituting the DAB antenna 3 are capacitively coupled to the defogger 2. Since current flows from the defogger 2 to both the antenna elements 33 and 34, the reception performance of the DAB antenna 3 can thereby be improved.
Also, as will be discussed later, when the second antenna element 34 and the auxiliary element 5 are capacitively coupled, the auxiliary element 5 can also be caused to function as a receiving antenna, thus enabling the DAB reception performance to be improved. Furthermore, as will be discussed later, the vertical elements are also caused to function as a receiving antenna in the case where the distance between the middle vertical element 42 and the auxiliary element 5 is 100 mm or less, thus enabling reception performance to be further improved.

3. Variations

Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the invention. Note that the following variations can be combined as appropriate.

3-1

The position of the DAB antenna 3 is not particularly limited, as long as the position enables capacitive coupling with the defogger 2. Accordingly, the DAB antenna 3 may be in the vicinity of the middle of the defogger 2 or upward of the defogger 2. Also, the antenna elements 33 and 34 are not particularly limited in terms of shape and orientation, and both the antenna elements 33 and 34 may, for example, be formed to face in opposite directions to each other.

3-2

The auxiliary element 5 is not particularly limited in terms of shape and position, and may be other than L-shaped as described above. Positioning is as described above, although connecting the auxiliary element 5 near the middle vertical element 42 or to the bus bar 21a on the side that the DAB antenna 3 is disposed will contribute to an improvement in reception performance. A plurality of auxiliary elements can also be provided, and any of these need only be capacitively coupled to the second antenna element 34.

3-3

The positional relationship of the DAB antenna 3 and the auxiliary element 5 is also not particularly limited. For example, in the above embodiment, the second antenna element 34 is disposed on the upper side of the auxiliary element 5, but may be on the lower side.

3-4

In the above embodiment, the first and second antenna elements 33 and 34 are capacitively coupled to different positions of the defogger 2 that includes the auxiliary element 5, but those positions are not particularly limited. For example, the first power supply part 31 and first antenna element 33 and the second power supply part 32 and second antenna element 34 can also be respectively disposed above or below the defogger. The first and second antenna elements 33 and 34 can also be capacitively coupled at the same place. However, when the first and second antenna elements 33 and 34 are capacitively coupled to different places of the defogger 2, the current that flows to the antenna elements 33 and 34 can be increased, thereby enabling the reception performance to be improved. Also, when capacitive coupling is performed in different places, the energy received with the entire defogger 2 can be efficiently supplied to the first power supply part 31 and the second power supply part 32. Note that "different places" refers to the case where, for example, the ends of the capacitive coupling are separated from each other by a distance of 25 mm or more, and are preferably separated by a distance of 50 mm or more, and more preferably by a distance of 100 mm or more.

3-5

The auxiliary element 5 is not necessarily required, and, for example, as shown in FIG. 2, the first and second antenna elements 33 and 34 can also both be capacitively coupled to the lowermost horizontal element 222 of the defogger 2.

3-6

The number and position of the vertical elements that are provided in the defogger 2 is not particularly limited, and can be changed as appropriate.

3-7

In the above embodiment, the DAB antenna 3 is provided as one mode of the antenna of the present invention, but the antenna of the present invention can also be applied to an antenna that receives broadcast waves of other media, or in other words, FM and like. Also, in the above embodiment, the DAB antenna is constituted by a first antenna element and a second antenna element, but is not particularly limited thereto, and a shared antenna that combines a DAB antenna and an antenna related to other media, such as an FM antenna, for example, can also be constituted.

3-8

In the above embodiment, an example is shown in which the window glass according to the present invention is applied to the rear glass of the automobile, but a vehicle to which this rear glass is attached may be made of one of resin and metal. For example, the window glass of the present invention can be attached to a backdoor provided with a resin cover member having a window opening part. Also, the inventor noted that it is more effective when the vehicle or door, whether resin or metal, to which this window glass is attached is capacitively coupled to the defogger 2 by both the antenna element on the core wire side and the antenna element on the grounding wire side, or in other words, when the antenna element on the grounding wire side and the defogger 2 are capacitively coupled and the defogger 2 is caused to function as ground, than directly coupling to a metal vehicle body or the like.

3-9

Also, the window glass of the present invention can also be applied to glass other than the rear glass of an automobile.

Working Examples

Hereinafter, working examples of the present invention will be described. The present invention is, however, not limited to the following working examples.
FIG. 3 is a window glass according to working example 1, and has a similar configuration to FIG. 1 of the above embodiment. The unit of measurement in FIG. 3 is millimeters (mm). Note that dimensions that are not included in other diagrams are assumed to be the same as those included in previous diagrams. The window glass according to the diagrams from FIG. 4 and all working examples and comparative examples including this working example 1 were evaluated by measuring the reception performance in DAB band III (174 to 240 MHz) under the following conditions.
That is, the sensitivity of each DAB antenna was measured, by emitting radio waves of DAB band III toward a vehicle to which a rear glass according to each working example and comparative example was attached in a radio wave darkroom, and receiving the broadcast waves using the DAB antenna of each rear glass. A network analyzer (model: E-5071C produced by Agilent) was utilized in measuring the sensitivity of each DAB antenna. The specific conditions in measurement are as follows.

- Attachment angle of glass plate: 62 degree tilt at a point on the lower edge in the up-down direction, 54 degree tilt at a point in the middle in the up-down direction, 45 degree tilt at a point on the upper edge in the up-down direction
- Angular resolution: Measured while rotating the vehicle 360 degrees every angle of three degrees
- Frequency resolution: measured every 3 MHz in a range of 174 MHz to 240 MHz
- Elevation angle between transmit position of radio waves and antenna: 1.7 degrees (assuming ground and horizontal direction are 0 degrees, and zenithal direction is 90 degrees)

Note that, in other working examples and comparative examples discussed later, the dimensions of the defogger are the same as working example 1. The remaining dimensions will be given later, and those not stated are the same as dimensions that have already appeared. Also, unless specifically stated otherwise, the first power supply part is connected to the core wire of a coaxial cable, and the second power supply part is connected to the grounding wire of the coaxial cable.

1. Evaluation 1

Hereinafter, the reception performances of working example 1 and comparative examples 1 and 2 will be considered. As shown in FIG. 3, working example 1 is a similar configuration to the above embodiment. FIG. 4 shows comparative example 1, which differs from working example 1 in terms of the provision of an auxiliary element, with an auxiliary element not being provided in comparative example 1. Also, FIG. 5 shows comparative example 2, which differs from working example 1 in terms of the orientation of the auxiliary element, with the second region of the adjustment element facing the right side. Thus, the auxiliary element and the second antenna element are not capacitively coupled. Also, the second antenna is not capacitively coupled to other regions of the defogger.
The reception performances of the above working example 1 and comparative examples 1 and 2 in the DAB frequency range were calculated as in FIG. 6. As shown in FIG. 6, working example 1 generally shows a high reception performance in all frequency ranges compared with comparative examples 1 and 2. In particular, in the frequency range of approximately 200 MHz or less, a reception performance that is much higher than comparative examples 1 and 2 is shown. Accordingly, it is noted that the reception performance increases when the two antenna elements are both capacitively coupled to the defogger. Note that the average of the reception sensitivities in the DAB frequency range was -5.9 dBd for working example 1, -7.8 dBd for comparative example 1, and -7.8 dBd for comparative example 2.

2. Evaluation 2

Working example 2 shown in FIG. 7 was prepared. This working example 2, unlike working example 1, is formed such that the second region of the auxiliary element passes on the upper side of the second antenna element. The remaining configuration is the same as working example 1.
The reception performance of this working example 2 is shown in FIG. 8 together with working example 1 and comparative example 1. As shown in FIG. 8, working example 2 shows a higher reception performance than comparative example 1, and further shows a substantially similar reception performance to working example 1. Accordingly, it was noted that the reception performance is generally the same whether the auxiliary element is disposed on the upper side or the lower side with respect to the second antenna element. Note that the average of the reception sensitivities in the DAB frequency range of working example 2 was -6.0 dBd.

3. Evaluation 3

Below, the connection position of an auxiliary element and the lowermost horizontal element was evaluated. In working example 2, the first region of the auxiliary element is connected to the intersection portion of the middle vertical element and the lowermost horizontal element, but, as shown in the following Table 1, working examples 3 to 9 in which the connection position was changed to the right side or the left side from this position were prepared, and the reception performances were calculated. Note that, in the following table, the connection position is shown with the intersection portion of the middle vertical element and the lowermost horizontal element as the origin, and with the left side as minus and the right side as plus from that position.

Table 2

	Connection Position of Aux. Element
Working Example 3	-150 mm
Working Example 4	-100 mm
Working Example 5	-50 mm
Working Example 2	0
Working Example 6	50 mm
Working Example 7	100 mm
Working Example 8	150 mm

The results are as shown in FIG. 9. As shown in this diagram, working examples 2 to 8 all show a reception performance that is generally more favorable than comparative example 1. In particular, more favorable reception performance is shown when the connection position of the auxiliary element is closer to the middle vertical element. As described above, it was noted that if the auxiliary element is at least connected at a position within ±150 mm from the middle vertical element, a favorable reception performance is obtained. Note that the average of the reception sensitivities in the DAB frequency range was -6.6 dBd for working example 3, -6.1 dBd for working example 4, -5.9 dBd for working example 5, -6.2 dBd for working example 6, -6.5 dBd for working example 7, and -6.8 dBd for working example 8.

4. Evaluation 4

Working example 9 and comparative example 3 were evaluated. Working example 9 shown in FIG. 10 differs from working example 1 in terms of the position of the DAB antenna. That is, in working example 9, the first power supply part was disposed near the right side of the first region of the auxiliary element, and the second power supply part was disposed on the left side of this first power supply part. The first antenna element connected to the first power supply part is capacitively coupled to the lowermost horizontal element, while extending on the left side. On the other hand, the second antenna element connected to the second power supply part extends, on the upper side of the second region of the auxiliary element, on the left side along this second region. The second antenna element is thereby capacitively coupled to the auxiliary element.
On the other hand, comparative example 3, as shown in FIG. 11, differs from working example 9 in terms of an auxiliary element not being provided. Accordingly, the first antenna element of comparative example 3 is capacitively coupled to the lowermost horizontal element, but the second antenna element is not capacitively coupled to the lowermost horizontal element.
The reception performances were calculated for working example 9 and comparative example 3. Working example 9 and comparative example 3 were also contrasted with working example 1 in which the position of the power supply part and the orientation of the antenna element differ. The results are as shown in FIG. 12. As shown in this diagram, when working example 1 and working example 9 are compared, working example 1 had a higher reception performance at frequencies of approximately 210 MHz and greater, although working example 1 and working example 9 both have a reception performance that is generally higher than comparative example 3. Accordingly, it was noted from working examples 1 and 9 that the reception performance improves as the power supply parts and the antenna elements that extend therefrom are separated further from the auxiliary element. Also, as described above, working example 1 has a higher reception performance than working example 9 at frequencies of approximately 210 MHz and greater, although since the frequency range in which such an effect can be expected is thought to be affected by various factors such as "the position of the power supply parts", "the length of the vertical elements", and "the length of capacitive coupling", reception performance in a desired frequency range can be improved by changing these factors as appropriate. In contrast, the performance of comparative example 3 is poor, since only one side is capacitively coupled, and an auxiliary element is not provided. Note that the average of the reception sensitivities in the DAB frequency range was -6.6 dBd for working example 9, and -7.7 dBd for comparative example 3.

5. Evaluation 5

Working example 10 in which the connection position of the auxiliary element differs from working example 9 was prepared. As shown in FIG. 13, in this working example 10, the first region of the auxiliary element was connected in the vicinity of the lower end part of the first bus bar on the left side (specifically, 50 mm toward the right side from the first bus bar), and the second region was connected so as to extend toward the right side from the lower end part of the first region. The remaining configuration relating to the antenna is the same as working example 9.
The reception performance was calculated for the above working example 10. Working example 10 was also contrasted with working example 9 in which the connection position of the auxiliary element differs and comparative example 3 in which an auxiliary element is not provided. The results are as shown in FIG. 14. When working examples 9 and 10 are contrasted, working example 9 has a higher reception performance than working example 10 in the frequency range smaller than approximately 200 MHz, but in the frequency range larger than approximately 200 MHz, working example 10 had a higher reception performance. Also, both working examples 9 and 10 showed a reception performance that is generally higher than comparative example 3. Note that the average of the reception sensitivities in the DAB frequency range of working example 10 was -6.1 dBd.

6. Evaluation 6

Working example 11 shown in FIG. 15 was prepared. Working example 10 is constituted such that the second antenna element passes on the upper side of the second region of the auxiliary element, whereas working example 11 is constituted such that the first region of the auxiliary element is shorten, and the second antenna element passes on the lower side of the second region.
The reception performances of working example 10, working example 11 and comparative example 3 are shown in FIG. 16. According to this diagram, it is noted that working example 10 has a generally higher reception performance than working example 11. However, both working examples 10 and 11 showed a reception performance that is generally higher than comparative example 1. Accordingly, it was noted that, in the case where the auxiliary element is connected to the bus bar on the left side, the second antenna element has a generally higher reception performance when disposed on the upper side of the auxiliary element.

7. Evaluation 7

Below, the connection position of the auxiliary element and the lowermost horizontal element was evaluated. In working example 10, the first region of the auxiliary element is connected in the vicinity of the bus bar on the left side, and, as shown in the following Table 3, working examples 12 to 14 in which the connection position of the first region of the auxiliary element was changed were prepared, and the reception performances were calculated. Note that, in the following table, the connection position is shown with the bus bar on the left side as the origin, and with the right side as plus from that position. Table 3

Position from Left Bus Bar

Working Example 10 50 mm

Working Example 12 100 mm

Working Example 13 150 mm

Working Example 14 200 mm
The results are as shown in FIG. 17. As shown in this diagram, working example 12 in which the connection position of the auxiliary element is 50 mm from the bus bar on the left side shows a substantially similar reception performance to working example 10. However, it was noted that, as with working examples 13 and 14, reception performance varies depending on the frequency when the connection position is separated from the bus bar on the left side by 100 mm or more. Note that the average of the reception sensitivities in the DAB frequency range was -7.0 dBd for working example 12, -6.6 dBd for working example 13, -7.1 dBd for working example 14, and -7.7 dBd for comparative example 3. Accordingly, the reception performances of working examples 13 and 14 were higher than comparative example 3 having no auxiliary element.
It was noted that, in the abovementioned working examples 3 to 8, a favorable reception performance is obtained if the auxiliary element is at least connected at a position within ±150 mm from the middle vertical element. On the other hand, working examples 10 to 14 are 100 mm or less. Accordingly, when these results are taken into consideration, it was noted that a favorable reception sensitivity is obtained if the auxiliary element is connected at a position that is 100 mm or less from a vertical element or a bus bar.

8. Evaluation 8

Working example 15 provided with two auxiliary elements was prepared. As shown in FIG. 18, in working example 15, an auxiliary element that is connected to the bus bar on the left side as in working example 10 is provided in addition to working example 9. The results are as shown in FIG. 19. As shown in this diagram, it was noted that working example 15 having two auxiliary elements shows the generally intermediate reception performance of working example 9 and working example 10 that each have one auxiliary element. Note that the average of the reception sensitivities in the DAB frequency range was -6.6 dBd for working example 15.

9. Evaluation 9

Working example 16 in which the direction in which the first antenna element extends was changed from working example 10 was prepared. As shown in FIG. 20, in working example 16, the first antenna element extends on the right side, but is the same as working example 10 in other respects. Also, as shown in FIG. 21, comparative example 4 in which the auxiliary element is removed from working example 16 was prepared.
FIG. 22 shows the reception performances of working example 16, working example 10, and comparative example 4. In this diagram, when working example 16 and working example 10 are contrasted, working example 10 showed a higher reception performance than working example 16 in a frequency range of approximately 215 MHz or greater, but has generally the same reception performance as working example 16 in a lower frequency range. Accordingly, the reception performance does not change much even if the orientation of the first antenna element changes . Also, both working examples 16 and 10 show a reception performance that is generally higher than comparative example 4. Note that the average of the reception sensitivities in the DAB frequency range was -7.2 dBd for working example 16, and -8.7 dBd for comparative example 4.

10. Evaluation 10

Working example 17 having the same antenna structure as working example 16 was prepared. In working example 17, however, the first power supply part is connected to the grounding wire, and the second power supply part is connected to the core wire. The results are as shown in FIG. 23. As shown in FIG. 23, it was noted that, in working example 17, the reception performance decreases greatly in a frequency range of approximately 225 MHz or greater, compared with working example 16. Accordingly, it was noted that the reception performance is more favorable when the core wire is connected to the first power supply part and the grounding wire is connected to the second power supply part. Note that the average of the reception sensitivities in the DAB frequency range was -7.0 dBd for working example 17.

Reference Signs List

1: Glass plate
2: Defogger
21a: Bus bar
21b: Bus bar
22: Horizontal element (horizontal heating wire)
3: DAB antenna
31: First power supply part
32: Second power supply part
33: First antenna element
34: Second antenna element

Claims

A window glass comprising:
a glass plate;

a defogger formed on the glass plate and having a pair of bus bars and a plurality of horizontal heating wires that join the pair of bus bars; and

an antenna formed on the glass plate,

wherein the antenna includes:
a first power supply part;

a first antenna element extending from the first power supply part;

a second power supply part; and

a second antenna element extending from the second power supply part,

the antenna is configured to receive a radio wave of a frequency range of a first media, using the first antenna element and the second antenna element, and

the first antenna element and the second antenna element are both capacitively coupled to the defogger.
The window glass according to claim 1,
wherein the first antenna element and the second antenna element are respectively capacitively coupled in different regions of the defogger.
The window glass according to claim 1 or 2,
wherein the defogger has an auxiliary element extending from one of the horizontal heating wires, and
at least one of the first antenna element and the second antenna element is capacitively coupled to the auxiliary element.
The window glass according to claim 3,
wherein the auxiliary element extends from an uppermost or lowermost horizontal heating wire, among the horizontal heating wires,
the defogger includes a first vertical element that intersects a plurality of the horizontal heating wires including at least the uppermost or lowermost horizontal heating wire to which the auxiliary element is connected, and
a distance between the first vertical element and the auxiliary element is 100 mm or less.
The window glass according to claim 4,
wherein the defogger includes a second vertical element disposed on the first power supply part or second power supply part side with respect to the first vertical element and intersecting a plurality of the horizontal heating wires, and
L≤α·λ/2 is satisfied, where L is a distance between the first vertical element and the second vertical element, α is a shortening coefficient of wavelength of the glass plate, and λ is a shortest wavelength corresponding to a frequency range of the first media.
The window glass according to any of claims 1 to 5, wherein the second power supply part is grounded.
The window glass according to any of claims 1 to 6, wherein the first media is DAB.
A backdoor comprising:
the window glass according to any of claims 1 to 7, and

a resin cover member having a window opening part to which the window glass is attached, and supporting the window glass.