Patent Description:
Various antennas are provided on the surface of window glass for vehicles (particularly the rear glass) that is installed in an automobile. For example, antennas for receiving broadcasting of various types of media, such as FM broadcasting, AM broadcasting, digital television broadcasting and DAB (Digital Audio Broadcasting; hereinafter, "DAB"), are provided. For example, in Patent Literature <NUM>-<NUM>, antennas for receiving FM broadcasting, AM broadcasting and/or digital television broadcasting are provided.

However, generally, a defogger for removing fog is disposed on the rear glass in addition to the antennas, and thus space for disposing the antennas is limited. Also, broadcasting of the abovementioned media essentially requires the provision of separate antennas, and sharing is not possible with some exceptions. Accordingly, a method for efficiently disposing multiple types of antennas on a vehicle window glass was desired. The present invention was made in order to solve the above problem, and an object of the invention is to provide a vehicle window glass on which multiple types of antennas can be efficiently mounted.

A vehicle window glass according to appended claim <NUM>. Additional features are defined in the dependent claims.

With a vehicle window glass according to the present invention, it is possible to efficiently mount multiple types of antennas.

Hereinafter, an embodiment of a vehicle window glass according to the present invention will be described, with reference to the drawings. <FIG> 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> may be referred to as the up-down direction or the vertical direction, and the left-right direction in <FIG> may be referred to as the left-right direction or the horizontal direction, based on the orientation of <FIG>, but this orientation is not intended to limit the invention.

As shown in <FIG>, the vehicle window glass according to the present embodiment has a glass plate <NUM> on which are mounted a defogger <NUM>, an FM/AM dual band antenna <NUM>, and a pair of digital television antennas <NUM> and <NUM>. Hereinafter, these members will be described in order.

A well-known glass plate for automobiles can be utilized for the glass plate <NUM>. For example, heat absorbing glass, common clear glass, common green glass or UV green glass may be utilized as the glass plate <NUM>. Such a glass plate <NUM> needs, however, to realize a visible light transmittance in line with safety standards of the country in which the automobile is used. For example, solar absorbance, visible light transmittance and other characteristics can be adjusted to satisfy safety standards. Below, an example of the composition of clear glass and an example of the composition of heat absorbing glass are shown.

The composition of heat absorbing glass can, for example, be given as a composition including total iron oxide in terms of Fe<NUM>O<NUM> (T-Fe<NUM>O<NUM>) at a ratio of <NUM> to <NUM> mass%, CeO<NUM> at a ratio of <NUM> to <NUM> mass%, and TiO<NUM> at a ratio of <NUM> to <NUM> mass%, based on the composition of clear glass, and in which the skeletal component (mainly SiO<NUM> or Al<NUM>O<NUM>) of the glass is reduced by an amount equivalent to the increase in T-Fe<NUM>O<NUM>, CeO<NUM> and TiO<NUM>.

Note that the type of glass plate <NUM> is not limited to clear glass or heat absorbing glass, and is selectable as appropriate for the embodiment. For example, the glass plate <NUM> may be a resin window made of acrylic resin, polycarbonate resin or the like.

Also, such a glass plate <NUM>, 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 sheets of glass.

Next, the defogger <NUM> will be described. As shown in <FIG>, the defogger <NUM> is disposed in the vicinity of the middle of the glass plate <NUM> in the up-down direction (defogger region), and is formed so as to extend across the entirety of the glass plate <NUM> in the left-right direction. Specifically, this defogger <NUM> 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 <NUM>. Between both of the bus bars 21a and 21b, a plurality of horizontal heating wires <NUM> are disposed in parallel at a predetermined interval, and heat for defogging is generated by power supply from the bus bars 21a and 21b. Also, in this defogger <NUM>, a vertical wire <NUM> that extends in the up-down direction is provided so as to generally divide these horizontal heating wires <NUM> equally in two in the horizontal direction. Also, the vertical wire <NUM> extends so as to join the horizontal heating wire that is uppermost (hereinafter, uppermost horizontal heating wire <NUM>) with the horizontal heating wire that is lowermost (hereinafter, lowermost horizontal heating wire <NUM>), but acts to assist the FM/AM dual band antenna <NUM> described later, rather than having a function of heating the glass plate <NUM>.

Next, the FM/AM dual band antenna <NUM> will be described. This FM/AM dual band antenna <NUM> is disposed on the glass plate <NUM> in an antenna region that is upward of the defogger <NUM>. Specifically, this FM/AM dual band antenna <NUM> is provided with a first power supply part <NUM> disposed directly above the defogger <NUM> on the left end side of the antenna region, an FM antenna body <NUM> that is disposed in the middle of the antenna region, a first main power supply element <NUM> that connects the first power supply part <NUM> to the FM antenna body <NUM>, and a first adjustment element <NUM> that extends upward from the first power supply part <NUM>. An FM main antenna is thereby constituted. Furthermore, a second power supply part <NUM> disposed directly above the defogger <NUM> and a sub power supply element <NUM> that extends upward from this second power supply part <NUM> are provided on the right end side of the antenna region as an FM sub-antenna. Furthermore, a second adjustment element <NUM> is provided on the lower side of the defogger <NUM>. Hereinafter, these elements constituting the FM/AM dual band antenna will be described in detail.

The FM antenna body <NUM> has a first horizontal part <NUM> that extends right and left along the vicinity of the upper edge of the glass plate <NUM>, a second horizontal part <NUM> that extends in parallel with this first horizontal part <NUM> and in parallel with the uppermost horizontal heating wire <NUM> of the defogger <NUM>, and a vertical part <NUM> that joins the middle of the first horizontal part <NUM> to the middle of the second horizontal part <NUM> and extends in the up-down direction. The second horizontal part <NUM> is provided to span substantially the entire distance between the power supply parts <NUM> and <NUM>, but the first horizontal part <NUM> is shorter and has a length that is generally half of the second horizontal part <NUM>. A television antenna region described later is thereby secured on both sides of the first horizontal part <NUM>. Also, on both side portions of the first horizontal part <NUM>, a short turned back part <NUM> that is turned back on the lower side and extends in parallel with the first horizontal part <NUM> is provided. Note that the sensitivity of the FM antenna increases as the first horizontal part <NUM> is disposed in a position closer to the upper edge of the glass plate <NUM>, as will be described later.

A distance G between the second horizontal part <NUM> and the uppermost horizontal heating wire <NUM> of the defogger <NUM> is <NUM> or less. To facilitate capacitive coupling of the FM antenna <NUM> and the defogger <NUM>, this distance G is preferably <NUM> or less, and more preferably <NUM> or less. Since the FM antenna <NUM> according to the present embodiment is, however, also for dual use as an AM antenna, the distance G is preferably <NUM> or more, since AM reception performance decreases when the antenna is too close to the defogger <NUM>.

Also, the vertical part <NUM> is disposed so as to extend in the up-down direction in the vicinity of the middle of the glass plate <NUM>, in correspondence with the abovementioned vertical wire <NUM> of the defogger <NUM>. The vertical parts <NUM> and <NUM> thereby resonate, and the sensitivity of the FM antenna can be improved.

Next, the first main power supply element <NUM> will be described. This first main power supply element <NUM> is formed in an L-shape, so as to extend on the right side from the first power supply part <NUM> along the upper side of the second horizontal part <NUM> of the FM antenna body <NUM> and, furthermore, to bend on the lower side at the left side of the vertical part <NUM> and be connected to the second horizontal part <NUM>. Accordingly, this first main power supply element <NUM> is directly connected to the FM antenna body <NUM>.

Next, the first adjustment element <NUM> will be described. This first adjustment element <NUM> is provided with a first vertical part <NUM> that extends upward from the first power supply part <NUM>, a first horizontal part <NUM> that extends on the right side from this first vertical part <NUM>, a second vertical part <NUM> that extends upward from the right end portion of the first horizontal part <NUM>, and a second horizontal part <NUM> that extends toward the right side from the upper end of this second vertical part <NUM>. The first vertical part <NUM> is short in length, and extends to the upper side of the first power supply element <NUM>. The first horizontal part <NUM> is approximately half the length of the first power supply element <NUM>, and extends to a position corresponding to the left end portion of the first horizontal part <NUM> of the FM antenna body <NUM>. The second vertical part <NUM> extends to downward of the left end portion of the first horizontal part <NUM> of the FM antenna body <NUM>, and the second horizontal part <NUM> is adjacent to the lower side of the first horizontal part <NUM> of the FM antenna body <NUM>, and is formed in parallel with the turned back part <NUM> at substantially the same length as the turned back part <NUM>.

Here, the optimal value of the length of the turned back part <NUM> and the second horizontal part <NUM> and the optimal value of the distance between the turned back part <NUM> and the second horizontal part <NUM> change depending on the impedance of the design value of the FM antenna <NUM>, and in the case where the impedance of the design value is <NUM>Ω, for example, the turned back part <NUM> and the second horizontal part <NUM> can be set as follows. That is, the optimal value of the length of the turned back part <NUM> and the second horizontal part <NUM> is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and particularly preferably <NUM> to <NUM>. Also, the optimal value of the distance between the turned back part <NUM> and the second horizontal part <NUM> is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and particularly preferably <NUM> to <NUM>.

As a result of a configuration such as the above, the region that is surrounded by the first horizontal part <NUM> and the second vertical part <NUM> of the first adjustment element <NUM> in the upper left of the glass plate <NUM> constitutes the abovementioned television antenna region.

Next, the sub power supply element <NUM> will be described. This sub power supply element <NUM> is provided with a first vertical part <NUM> that extends upward from the second power supply part <NUM>, a first horizontal part <NUM> that extends on the left side from this first vertical part <NUM>, a second vertical part <NUM> that extends upward from the left end portion of the first horizontal part <NUM>, and a second horizontal part <NUM> that extends toward the left side from the upper end of this second vertical part <NUM>. The first vertical part <NUM> is short in length, and is substantially the same length as the first vertical part <NUM> of the first adjustment element <NUM>. The first horizontal part <NUM> is substantially the same length as the first horizontal part <NUM> of the first adjustment element <NUM>, and extends to a position corresponding to the right end portion of the first horizontal part <NUM> of the FM antenna body <NUM>. The second vertical part <NUM> extends to downward of the right end portion of the first horizontal part <NUM> of the FM antenna body <NUM>, and the second horizontal part <NUM> is adjacent to the lower side of the first horizontal part <NUM> of the FM antenna body <NUM>, is in parallel with the turned back part <NUM> and slightly longer than the turned back part <NUM>, and is adjacent to the vertical part <NUM> of the FM antenna body <NUM>.

As a result of such a configuration, the region that is surrounded by the first horizontal part <NUM> and the second vertical part <NUM> of the sub power supply element <NUM> in the upper right of the glass plate <NUM> constitutes the abovementioned television antenna region.

The above FM antenna <NUM> is also used as an AM antenna, and the first power supply part <NUM> is connected to an FM and AM tuner (illustration omitted) via a lead wire or the like. An amplifier may be inserted upstream of the tuner.

Next, the second adjustment element <NUM> will be described. The second adjustment element <NUM> is provided with a vertical part <NUM> that extends downward from the lower end portion of the vertical wire <NUM> of the defogger <NUM> and a horizontal part <NUM> that is linked to the lower end portion of this vertical part <NUM> and extends in the left-right direction.

Next, the digital television antennas will be described. Here, for convenience of description, the left side will be referred to as a first digital television antenna <NUM>, and right side will be referred to as a second digital television antenna <NUM>. As described above, these digital television antennas <NUM> and <NUM> are respectively disposed in the television antenna regions on both sides of the FM antenna body <NUM>, and since the digital television antennas are the same apart from being symmetrical in shape, hereinafter the first digital television antenna <NUM> will be described.

The first digital television antenna <NUM> is constituted by an antenna body element <NUM> and a ground connection element <NUM>. The antenna body element <NUM> has a television power supply part <NUM> disposed on the upper left of the glass plate <NUM>, and three horizontal parts 412a to 412c that branch in three from this power supply part <NUM>, and extend toward the right side. The three horizontal parts 412a to 412c extend in parallel with each other so as to be arranged side by side in the up-down direction, and are formed at different lengths. In this example, the middle horizontal part 412b is the longest, and the upper horizontal part 412a is the shortest. By providing such horizontal parts 412a to 412c having different lengths, lengths preferable for reception of high frequency and low frequency digital television broadcast waves can be supported, for example. On the other hand, the ground connection element <NUM> is provided with a ground terminal area <NUM> disposed on the lower side of the first television power supply part <NUM>, and a ground body <NUM> that extends upward from this ground terminal area <NUM> to the left side of the first television power supply part <NUM>.

Also, a distance E between the lowermost side of this first digital television antenna <NUM> (here, lowermost horizontal part 412c of the antenna body element <NUM>) and the defogger <NUM> is preferably <NUM> or more, and more preferably <NUM> or more. This is because the broadcast waves of digital television are horizontally polarized waves, and thus sensitivity decreases when the antenna is disposed close to the defogger <NUM> including a large number of horizontal heating wires <NUM>.

Also, a digital television receiver (illustration omitted) is provided in the automobile, and the television power supply part <NUM> is connected to an inner conductor of a coaxial cable (illustration omitted) connected to this receiver. On the other hand, the ground terminal area <NUM> is electrically connected to an outer conductor of the coaxial cable and is grounded.

A defogger <NUM> and antennas <NUM> to <NUM> such as described above are constituted by combining wire rods, but can be formed by laminating a conductive material having conductivity on the surface of the glass plate <NUM> so as to have a predetermined pattern. Such a material need only have conductivity, and is selectable as appropriate for the embodiment, with silver, gold, platinum and the like given as examples. Specifically, 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 <NUM>.

Next, a manufacturing method of the window glass according to the present embodiment will be described. The glass plate <NUM> 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 <NUM> with a press or a self-weight bending method for bending the glass plate <NUM> under its own weight.

Here, at the time of shaping the glass plate <NUM> with these respective methods, the glass plate <NUM> is heated to a vicinity of the softening point in a heating furnace. Before being placed in this heating furnace, the glass plate <NUM> is flat in shape, and a paste for the various materials described above, such as a silver paste, for example, is printed on the surface of this glass plate <NUM>. Then, by placing the glass plate <NUM> in the heating furnace, the glass plate <NUM> is shaped and the silver paste printed on the glass plate <NUM> is baked to form the defogger <NUM> and the antennas <NUM> to <NUM>.

According to the present embodiment as described above, the following effects can be obtained.

Next, a second embodiment of the vehicle window glass according to the present invention will be described, with reference to <FIG> is a front view of the rear glass of an automobile to which the vehicle window glass according to the present embodiment is applied. Hereinafter, only the differences from the first embodiment will be described. In the second embodiment, the shape of the FM/AM dual band antenna <NUM> is different from the first embodiment and, also, a DAB antenna <NUM> is disposed instead of a digital television antenna. Furthermore, a second adjustment element is not provided. Hereinafter, the differences will be described.

As shown in <FIG>, the FM/AM dual band antenna <NUM> according to the present embodiment differs in the shape of the FM antenna body, the power supply element, the first adjustment element, the main power supply element, and the sub power supply element of the FM sub-antenna. Hereinafter, these parts will be described.

First, the FM antenna body <NUM> of the present embodiment, similarly to the first embodiment, has a first horizontal part <NUM>, a second horizontal part <NUM> that extends in parallel with this first horizontal part <NUM>, and a vertical part <NUM> that joins the middle of the first horizontal part <NUM> to the middle of the second horizontal part <NUM> and extends in the up-down direction. A difference from the first embodiment is with the second horizontal part <NUM>. The second horizontal part <NUM> according to the present embodiment is connected at the end portion on the left side to the first power supply part <NUM>. Also, the right side of the second horizontal part <NUM> is formed to be slightly shorter than in the first embodiment.

The first adjustment element <NUM> is constituted as follows. The first adjustment element <NUM> of the present embodiment is formed so as to extend upward along the left end edge of the glass plate <NUM> from the first power supply part <NUM>, and to extend in the horizontal direction from the vicinity of the upper end of the glass plate <NUM>. The horizontal portion of the upper end of the first adjustment element <NUM> is adjacent to the lower side of the first horizontal part <NUM> of the FM antenna body <NUM>, and extends horizontally along this first horizontal part <NUM>. The first adjustment element <NUM> is thereby capacitively coupled to the first horizontal part <NUM> of the FM antenna body <NUM>.

In the present embodiment, two third main power supply elements <NUM> are connected to an intermediate part of the first adjustment element <NUM>. These third main power supply elements <NUM> are disposed in parallel with each other, and the right end portions thereof are each connected to the vertical part <NUM> of the FM antenna body <NUM>.

The sub power supply element <NUM> is constituted as follows. The sub power supply element <NUM> according to the present embodiment extends linearly on the left side from the second power supply part <NUM>, and is adjacent to and extends along the upper side of the second horizontal part <NUM> of the FM antenna body <NUM>.

Next, the DAB antenna will be described. DAB is a digital radio broadcasting standard that is employed in Europe and elsewhere. In DAB, band <NUM> having a frequency band of <NUM> to <NUM> and L band having a frequency band of <NUM> to <NUM> are mainly used. In the present embodiment, a DAB antenna <NUM> whose main frequency band is band <NUM> is targeted.

The DAB antenna <NUM> according to the present embodiment is constituted by an antenna body element <NUM> and a ground connection element <NUM>. The antenna body element <NUM> includes a DAB power supply part <NUM> provided in the vicinity of the upper right corner of the glass plate <NUM>, and a first part <NUM> that extends therefrom toward the left side along the upper end edge of the glass plate <NUM>. This first part <NUM> extends, in the horizontal direction, to slightly to the right side of the right end portion of the first horizontal part <NUM> of the FM antenna body <NUM>, and a second part <NUM> that extends downward is connected to the right end portion of this first part <NUM>. The second part <NUM> extends to slightly upward of the sub power supply element <NUM>, and a third part <NUM> that extends to the vicinity of the right side edge of the glass plate <NUM> in the left-right direction is connected to a lower end portion of this second part <NUM>.

A third part <NUM> is positioned as the lowermost part of the DAB antenna <NUM>, and a distance D between this third part <NUM> and the uppermost horizontal heating wire <NUM> of the defogger <NUM> is, for example, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>. This is because the second part <NUM>, which is the vertical element of the DAB antenna <NUM>, will be shortened in length when the distance D increases. To be more specific, since the element length in the vertical direction greatly affects the receiver sensitivity in the DAB antenna <NUM>, there is a risk that shortening the length of the second part <NUM> will lead to a decrease in the sensitivity of the DAB antenna <NUM>. On the other hand, there is a risk that the defogger <NUM> and the DAB antenna <NUM> will become capacitively coupled when the distance D is smaller than <NUM>, and the distance D is preferably larger than <NUM> in order to prevent this.

On the other hand, the ground connection element <NUM> includes a ground connection part <NUM> and a linear main body part <NUM> that extends upward therefrom. The ground connection part <NUM> is disposed slightly downward from the DAB power supply part <NUM>, and the main body part <NUM> extends along the first part <NUM> of the antenna body element <NUM>, slightly to the left side of the first part <NUM>, and extends to near the second part <NUM>.

Also, a DAB receiver (illustration omitted) is provided in the automobile, and the DAB power supply part <NUM> is connected to an inner conductor of a coaxial cable (illustration omitted) connected to this receiver. On the other hand, the ground connection part <NUM> is electrically connected to an outer conductor of the coaxial cable and is grounded.

As described above, according to the present embodiment, the following effects can be obtained.

Next, a third embodiment of the vehicle window glass according to the present invention will be described, with reference to <FIG> is a front view of the rear glass of an automobile to which the vehicle window glass according to the present embodiment is applied. Hereinafter, only the differences from the second embodiment will be described. In the third embodiment, the shape of the FM/AM dual band antenna <NUM> differs and, also, the second adjustment element <NUM> is provided on the lower side of the defogger <NUM>. This second adjustment element, however, differs in shape from that of the first embodiment. Note that since the first adjustment element <NUM> is the same as in the second embodiment, description thereof is omitted.

In the FM/AM dual band antenna <NUM> according to the present embodiment, the right end portion of the first horizontal part <NUM> of the FM antenna body <NUM> is connected to the upper end of the vertical part <NUM>. That is, the first horizontal part <NUM> and the vertical part <NUM> form an L-shape. A large space is thereby secured on the upper right of the glass plate <NUM>. Also, the right end portion of the second horizontal part <NUM> of the FM antenna body <NUM> is formed by a straight line. Furthermore, the sub power supply element <NUM> of the FM sub-antenna is also formed by a straight line, and is disposed so as to extend along the upper side of the second horizontal part <NUM> of the FM antenna body <NUM>. At this time, the amount by which the second horizontal part <NUM> and the sub power supply element <NUM> overlap in the right-left direction is shorter than in the second embodiment. For example, the length of overlap can be set to approximately <NUM> to <NUM> % compared with the second embodiment. Specifically, when the length of overlap in the second embodiment is set to <NUM>, the length of overlap in the third embodiment can be set to <NUM>.

The second adjustment element <NUM> is provided with a first horizontal part <NUM> that extends directly below and in parallel with the lowermost horizontal heating wire <NUM> of the defogger <NUM>, a second horizontal part <NUM> that extends in the left-right direction downward of this first horizontal part <NUM>, and a vertical part <NUM> that links both these horizontal parts <NUM> and <NUM>. The first horizontal part <NUM> is approximately half the length of the defogger <NUM> in the horizontal direction, and the second horizontal part <NUM> is formed to be even shorter. Also, the second horizontal part <NUM> is disposed in the vicinity of the lower edge of the glass plate <NUM>. The vertical part <NUM> is disposed in a position corresponding to the vertical wire <NUM> of the defogger <NUM>.

The present embodiment, in particular, is able to reduce the influence exerted on the receiver sensitivity of FM broadcast waves by the headrest of the backseat of an automobile. That is, the headrest is fixed by a metal rod-like member so as to be slidable along the upper end portion of the backseat, and the rod-like member also moves upward and is exposed when the headrest is raised, thus weakening the receiver sensitivity of FM broadcast waves. Specifically, as a result of the FM/AM dual band antenna <NUM> being high-frequency coupled to an LC series resonant circuit that is constituted by the headrest and the seat frame, radio waves that should originally be received with the FM/AM dual band antenna <NUM> were trapped by the headrest, causing an antenna sensitivity "dip". In particular, the receiver sensitivity of FM broadcast waves decreased, due to an L value of the LC series resonant circuit changing as a result of the headrest being raised, and a dip frequency in which the receiver sensitivity decreases moving from out-of-band to in-band. In view of this, in the present embodiment, the influence of the headrest is reduced, by changing the shape of the FM/AM dual band antenna <NUM> from the second embodiment and further providing the second adjustment element <NUM>, as described above. Specifically, the following measures (<NUM>) to (<NUM>) were applied.

Note that the influence of the headrest can be reduced by implementing even one of the above measures (<NUM>) to (<NUM>).

Embodiments of the present invention have been described above, but the present invention is not limited to the foregoing embodiments, and various changes can be made without departing from the scope of the appended claims. Note that the following variations can be combined as appropriate.

In the FM main antenna shown in <FIG>, a short second vertical part <NUM> that extends on the lower side is linked to the right end portion of the first horizontal part <NUM> of the FM antenna body <NUM>. Also, the right end portion of the second horizontal part <NUM> is formed linearly. Furthermore, the two main power supply elements provided in the second embodiment have been reduced to one.

The FM sub-antenna shown in <FIG> is provided on the lower side of the defogger <NUM>. That is, the second power supply part <NUM> is provided directly under the defogger <NUM> on the left side edge of the glass plate <NUM>. The sub power supply element <NUM> extends along the lowermost horizontal heating wire <NUM> of the defogger <NUM> from the second power supply part <NUM>. Also, an L-shape extension wire <NUM> is provided on the lower end portion of the vertical wire <NUM> of the defogger <NUM>. That is, this extension wire <NUM> extends downward from the lower end portion of the vertical wire <NUM>, and further extends in the horizontal direction toward the left side. The horizontal portion of this extension wire <NUM> extends on the lower side of and along the sub power supply element <NUM>. Note that this extension wire <NUM> is equivalent to the second adjustment element <NUM> of the above embodiments.

As described above, the FM sub-antenna is not particularly limited in terms of location, and can be disposed in various places such as the lower right end portion of the glass plate <NUM>. The FM main antenna is also not particularly limited in terms of disposition location.

Hereinafter, working examples of the present invention will be described. The present invention is, however, not limited to the following working examples.

The length of the overlapping portion of the first horizontal part of the FM antenna body and the adjustment element, or in other words, a length a of capacitive coupling, in the vehicle window glass shown in the first embodiment was investigated. Here, a working example <NUM> in which the length a was <NUM> in <FIG> and a working example <NUM> in which the length a was <NUM> in <FIG> were prepared. Note that the unit of the numerical values in <FIG> is millimeters (the same applies to other diagrams).

The reception performance of the FM frequency band (<NUM> to <NUM>) in the FM main antenna was measured as follows using these working examples <NUM> and <NUM>.

That is, having mounted the window glass according to each of the above working examples in an automobile, radio waves (vertically polarized waves, horizontally polarized waves, obliquely polarized waves, etc.) were emitted onto the vehicle, and sensitivity was measured. Measurement was carried out under the following conditions.

Note that this measurement method was similarly applied in the working examples described later.

The results are as shown in <FIG>. As shown in <FIG>, when the length a of capacitive coupling was long, the receiver sensitivity in the <NUM> to <NUM> frequency range improved, whereas the receiver sensitivity in the <NUM> to <NUM> frequency range was high when the length a of capacitive coupling was short. Note that, in the graph of <FIG>, the vertical axis is normalized, such that the maximum value of in-band antenna sensitivity will be <NUM> dBd. This similarly applies to <FIG> and <FIG> described later.

With the window glass shown in <FIG>, a working example <NUM> in which a distance b between the first horizontal part of the sub power supply element and the defogger was <NUM> and a working example <NUM> in which the distance b was <NUM> were prepared. In this case, the length of the second vertical part (reference sign <NUM> in <FIG>) of the sub power supply element is changed. The receiver sensitivity of the FM main antenna and the FM sub-antenna was measured for these working examples. The results are as shown in <FIG>. That is, it was revealed that the receiver sensitivity in the FM main antenna improves across the entire frequency range when the distance b is lengthened. On the other hand, the receiver sensitivity in the FM sub-antenna was slightly higher in a frequency range higher than approximately <NUM> when the distance b was shorter.

With the window glass shown in <FIG>, a working example <NUM> in which a distance c between the second horizontal part of the sub power supply element and the defogger was <NUM>, a working example <NUM> in which the distance c was <NUM>, and a working example <NUM> in which the distance c was <NUM> were prepared. In this case, the length of the second vertical part (reference sign <NUM> in <FIG>) of the sub power supply element is changed. The receiver sensitivity of the FM main antenna and the FM sub-antenna was measured for these working examples. The results are as shown in <FIG>. That is, it was revealed that the receiver sensitivity in the FM main antenna improves across the entire frequency range when the distance c is lengthened. On the other hand, the receiver sensitivity in the FM sub-antenna was slightly higher in a frequency range higher than approximately <NUM> when the distance c was shorter.

With the window glass shown in <FIG>, a working example <NUM> in which the length of overlap of the second horizontal part of the sub power supply element and the first horizontal part of the FM antenna body, that is, a length d of capacitive coupling, was <NUM>, a working example <NUM> in which the length d was <NUM>, and a working example <NUM> in which the length d was <NUM> were prepared. At this time, a turned back part (reference sign <NUM> in <FIG>) on the right side of the first horizontal part of the FM antenna body was not provided. The receiver sensitivity of the FM main antenna and the FM sub-antenna was measured for these working examples. The results are as shown in <FIG>. That is, it was revealed that the receiver sensitivity in the FM main antenna becomes higher in a frequency range of generally <NUM> or higher as the distance d becomes longer. On the other hand, the receiver sensitivity in the FM sub-antenna was higher in a frequency range of generally <NUM> or higher when the distance d was shorter.

With the window glass shown in <FIG>, a working example <NUM> in which a distance e between the first horizontal part of the FM antenna body and the upper edge of the glass plate was <NUM> and a working example <NUM> in which the distance e was <NUM> were prepared. The receiver sensitivity of the FM main antenna was measured for these working examples. The results are as shown in <FIG>. That is, it was revealed that the receiver sensitivity improves slightly across the entire frequency range when the distance e is shortened.

Taking the window glass shown in <FIG> as a working example <NUM> and the window glass shown in <FIG> as a working example <NUM>, the receiver sensitivity of the FM main antenna was measured for these working examples. The results are as shown in <FIG>. That is, the working example <NUM> had a higher receiver sensitivity over substantially all of the FM frequency range.

<FIG> corresponding to the second embodiment was taken as a working example <NUM>. Also, <FIG> corresponding to the third embodiment was taken as a working example <NUM>. A mode of <FIG> in which the second adjustment element was removed from the window glass shown in the working example <NUM> and the first horizontal part of the FM antenna body extended on the right side was taken as a working example <NUM>, and a mode of <FIG> in which the second horizontal part of the FM antenna body extended on the left side from this working example <NUM> and connected to the first power supply part was taken as a working example <NUM>. That is, the working examples <NUM> to <NUM> each applied one or more of the measures (<NUM>) to (<NUM>) shown in the third embodiment.

The change in the receiver sensitivity of the FM main antenna and the FM sub-antenna between a position (reference position) in which the headrest of the backseat was not raised and a position (raised position) in which the headrest was raised and the rod-like member was exposed was measured for the working examples <NUM> to <NUM>. At this time, the exposed length of the rod-like member of the headrest was approximately <NUM>. The results are as shown in the following Table <NUM>.

Table <NUM> shows the difference in receiver sensitivity in the vicinity of a frequency of <NUM> between the headrest being in the reference position and the raised position. That is, the decrease in receiver sensitivity when moving from the reference position to the raised position is shown. The unit is dBd. In the working examples <NUM> to <NUM> to which measures for the headrest were applied, the decrease (difference between the reference position and the raised position) in receiver sensitivity, even with the headrest in the raised position, is generally small compared with the working example <NUM>. Also, when the working examples <NUM> to <NUM> are compared, the decrease in receiver sensitivity in the raised position increases in order of the working examples <NUM>, <NUM> and <NUM>. Accordingly, the working example <NUM> to which all of the measures (<NUM>) to (<NUM>) shown in the third embodiment were applied was least likely to be affected by the headrest being raised, and the influence of raising the headrest increased as the measures were reduced.

A working example <NUM> obtained by transforming <FIG> was created. As shown in <FIG>, the differences between this working example <NUM> and the form of <FIG> are as follows. Note that, for convenience of description, the reference signs given are the corresponding reference signs of the configuration of <FIG>.

Claim 1:
A vehicle window glass comprising:
a glass plate (<NUM>) having a defogger region and an antenna region;
a defogger (<NUM>) disposed in the defogger region and having a plurality of horizontal heating wires (<NUM>) and provided with a vertical wire (<NUM>) extending in the up-down direction so as to divide the horizontal heating wires (<NUM>) equally in two in the horizontal direction, wherein the vertical wire (<NUM>) joins the upmost horizontal heating wire (<NUM>) with the lowermost horizontal heating wire (<NUM>); and
an antenna including at least an FM antenna (<NUM>) and disposed in the antenna region,
wherein the FM antenna (<NUM>) includes:
a first power supply part (<NUM>) disposed on the glass plate (<NUM>); and
an FM antenna body (<NUM>) having a first horizontal part (<NUM>), a second horizontal part (<NUM>) closer to the defogger (<NUM>) than is the first horizontal part (<NUM>), at least one third main power supply element (<NUM>), and at least one vertical part (<NUM>) linking both the horizontal parts (<NUM>, <NUM>), and connected to the first power supply part (<NUM>),
wherein the at least one third main power supply element (<NUM>) connects the vertical part (<NUM>) to the first power supply part (<NUM>),
the vertical part (<NUM>) is disposed so as to extend in the up-down direction in the vicinity of the middle of the glass plate (<NUM>), in correspondence with the vertical wire (<NUM>) of the defogger (<NUM>), and
the vertical part (<NUM>) joins the middle of the first horizontal part (<NUM>) to the middle of the second horizontal part (<NUM>).