JP2004260504A - Antenna structure for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna structure for a vehicle which is simple, light in weight and low in cost, and by which electromagnetic noise during radio reception can be reduced and low sensitivity during especially weak AM broadcasting reception can be compensated. <P>SOLUTION: The antenna structure 11 for a vehicle is provided with a rear window pane 13 which is placed in the rear of the vehicle 12, a rear defogger 14 which is provided to the rear window pane 13, antenna filaments 15 for radio reception which are provided to the rear window pane 13 with the rear defogger 14 and a shield line 17 which is placed in a space 16 between the rear defogger 14 and the antenna filaments 15. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle antenna structure, and more particularly, to a vehicle antenna structure including a rear window glass, a rear defogger (heater wire), and an antenna wire.
[0002]
[Prior art]
In FIG. 7, recently, mainly for aesthetic reasons, a rear window glass 2 provided at the rear of the vehicle 1 is provided with a radio defogger 3 for preventing fogging and an antenna wire 4 for radio reception. The antenna wire 4 and the rear defogger 3 are respectively printed on the rear window glass 2 using a conductive paste, and these are generally arranged in a vertically close state.
[0003]
By the way, if the antenna wire 4 and the rear defogger 3 are arranged vertically adjacent to each other, electromagnetic noise that enters through the power supply line of the rear defogger 3 and is mixed into the antenna wire 4 due to coupling or radiation. Induced, causing noise interference during radio reception.
[0004]
In the case of an AM broadcast wave, it is difficult to obtain a sufficient length and antenna area from the shape of the antenna wire 4 for the wavelength. Therefore, the receiving efficiency was low and the antenna induced voltage was low. Further, since the AM receiving circuit does not include the noise limiter unlike the FM receiving circuit, the AM receiving circuit tends to be relatively susceptible to electromagnetic noise. These factors contributed to the susceptibility to electromagnetic noise.
[0005]
At present, there is a vehicle equipped with a device for removing noise or a noise filter mounted on a vehicle (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-9-107218 (page 3, FIG. 1)
[0007]
[Problems to be solved by the invention]
When measures were taken by mounting the above-mentioned noise removing device or the above-mentioned noise filter on a vehicle, sufficient satisfaction was not always obtained in terms of weight, cost and performance. Therefore, the present invention has been made in view of such circumstances, and is simple, lightweight, and low in cost. In addition, electromagnetic wave noise at the time of radio reception is reduced. It is an object to provide a vehicle antenna structure capable of compensating for the above.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a vehicle antenna structure including: a rear window glass provided at a rear portion of a vehicle; an electrically heated rear defogger provided on the rear window glass; An antenna wire provided on the rear window glass together with the defogger, wherein the rear defogger serving as a noise radiating source is electromagnetically provided in a space between the rear defogger and the antenna wire. It is characterized by the fact that a shield line is provided to isolate it.
[0009]
According to a second aspect of the present invention, in the vehicle antenna structure according to the first aspect, the shield line is disposed in a state of being close to the rear defogger and the antenna wire. It is characterized by.
[0010]
A vehicle antenna structure according to a third aspect of the present invention is the vehicle antenna structure according to the second aspect, wherein a distance between the shield line and the rear defogger is d1, and the shield line and the antenna wire are disposed between the shield line and the rear defogger. Wherein the shield line is arranged so that d1 <d2 when the interval between the two is d2.
[0011]
A vehicle antenna structure according to a fourth aspect of the present invention is the vehicle antenna structure according to any one of the first to third aspects, wherein the shield line extends along a direction between the rear defogger and the antenna wire. It is characterized by being formed to be wide.
[0012]
According to the first aspect of the present invention, electromagnetic C-coupling (capacitive coupling) and M-coupling (inductive coupling) directly generated between the rear defogger and the antenna wire are released, and the shield line and the rear defogger are separated. And the C and M bonds with the substrate become dense. Then, the electromagnetic wave noise is absorbed by this, and the noise induced in the antenna wire is reduced. Therefore, the electromagnetic wave noise at the time of radio reception is reduced, and it is possible to compensate for the lack of sensitivity particularly at the time of reception of weak AM broadcast. In addition, as will be described in the section of the embodiment of the invention, the shield line is configured to be extremely simple and lightweight. Further, it is configured so that the cost can be reduced.
[0013]
According to the second aspect of the present invention, the distance between the shield line and the rear defogger is reduced, and the C and M couplings between them are further increased. Therefore, the electromagnetic wave noise is efficiently absorbed, and the noise induced in the antenna wire is further reduced.
[0014]
According to the third aspect of the present invention, the shield line and the rear defogger are brought closer to each other, and the C and M couplings between them are further increased. On the other hand, the shield line is separated from the antenna wire, and adverse effects on the antenna impedance can be avoided. Further, when the shield line is separated from the antenna wire, the effective opening area of the antenna is widened, and a decrease in antenna induced voltage (a decrease in reception sensitivity) is prevented.
[0015]
According to the fourth aspect of the present invention, the effective area of the shield line is widened, and the electromagnetic noise is further reduced. In addition, how to increase the effective area of the shield line will be described in the section of the embodiment of the present invention.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing one embodiment of a vehicle antenna structure of the present invention. FIG. 2 is a diagram showing another example of the shield line, and FIGS. 3 to 6 are graphs of effect verification by using electromagnetic field simulation.
[0017]
In FIG. 1, a vehicle antenna structure 11 according to the present invention includes a rear window glass 13 provided on a rear portion of a vehicle 12, a rear defogger 14 for preventing fogging provided on the rear window glass 13, and a rear defogger 14. It comprises a radio receiving antenna wire 15 provided on the rear window glass 13, and a shield line 17 provided in a space 16 between the rear defogger 14 and the antenna wire 15.
[0018]
Here, it is assumed that the rear defogger 14, the antenna wire 15 and the shield line 17 are provided on the surface of the rear window glass 13, the film in the laminated glass, or the like. Hereinafter, each configuration will be described.
[0019]
The rear defogger 14 is of an electric heating type, and includes a bus bar 18 provided on both left and right sides of the rear window glass 13 and a plurality of heater wires 19 connected to the bus bar 18. I have. That is, the rear defogger 14 is configured similarly to a known one. The rear defogger 14 is provided from substantially the center of the rear window glass 13 to below. A power supply and a grounding part are connected to the heater wire 19, respectively.
[0020]
The antenna wire 15 is provided for receiving AM broadcast waves and FM broadcast waves, and is arranged above the rear window glass 13. The antenna wire 15 is configured similarly to a known one. In addition, another antenna such as a remote control antenna may be provided together with the antenna wire 15.
[0021]
Although not particularly limited, the shield line 17 is provided by pattern printing, for example, similarly to the rear defogger 14 and the antenna wire 15, and one end (or both ends) is connected to a ground portion. The shield line 17 is connected such that the grounding resistance is as low as possible with respect to the grounding portion (preferably, the shielding line 17 is grounded to the body of the vehicle 12 at the shortest distance).
[0022]
Such a shield line 17 is disposed in parallel with the upper end of the rear defogger 14 and the lower end of the antenna wire 15, and separates them from each other and is in close proximity thereto. Preferably, if the distance between the shield line 17 and the upper end of the rear defogger 14 is d1, and the distance between the shield line 17 and the lower end of the antenna wire 15 is d2, the shield line 17 satisfies d1 <d2. It is arranged to become. In the present embodiment, it is arranged at a position near the rear defogger 14 which is a noise radiation source.
[0023]
The shield line 17 is inserted between the rear defogger 14 and the antenna wire 15 so as to electromagnetically isolate (shield) the two. In other words, the shield line 17 is provided as a member for electromagnetically shielding the rear defogger 14.
[0024]
As can be seen from the above, the shield line 17 is configured to be extremely simple and lightweight. In addition, it is configured so that the cost can be reduced.
[0025]
Note that a shield line as shown in FIG. 2 may be provided instead of the shield line 17. That is, a wide shield line 20 as shown in FIG. 2A may be provided in the space 16 between the rear defogger 14 and the antenna wire 15. The shield line 20 is formed thicker than the shield line 17. The direction of increasing the width is the direction between the rear defogger 14 and the antenna wire 15, and the effect is shown in FIG. This is effective because the effective area is widened.
[0026]
FIG. 2B shows a triple line type shield line 21. The shield line 21 is formed by combining three filaments 21a as illustrated. The shield line 21 is formed to be wider in the width direction than the shield line 17. Here, it is assumed that the number of the filaments 21a can be two (double line type) or four or more. The effect on the number of shield lines is shown in FIG. This is effective because the effective area is widened.
[0027]
FIG. 2C shows a grid-like surface type shield line 22. The shield line 22 is formed as shown by a plurality of filaments 22a. The shield line 22 is formed so as to be wider in the width direction than the shield line 17. This is effective because the effective area is widened.
[0028]
3 to 6 show the results of verifying the effect of the shield line using electromagnetic field simulation.
[0029]
The outline of the simulation model is
(1) Antenna: L = 1000mm 1φ, 50Ω coaxial feed × 2
(2) Distance between antennas: 30 mm
(3) Shield line: L = 1000 mm 1φ is standard, and the number, the distance to the antenna, the width, and the length are changed.
(4) Glass plate: (x, y, z) = (1100, 100, 3) mm
(5) Air layer: (x, y, z) = (1100, 100, 40) mm
And
Then, a transmission loss and a shield effect when a shield line was inserted between the two antennas were simulated.
[0030]
The effect verification results in FIGS. 3 to 6 show that in the case of transmission loss, the larger the negative value, the greater the attenuation. In the case of the shield effect, the larger the value, the greater the attenuation. These effectively work to reduce electromagnetic wave noise.
[0031]
In FIG. 3A, it can be seen that when one shield line is inserted, the attenuation is greater than when there is no shield line (result of the with shield in the graph, corresponding to a conventional vehicle antenna structure). . Also, it can be seen that when two shield lines are inserted, the attenuation is greater than when one shield line is inserted. The effect on the transmission loss is obtained.
[0032]
In FIG. 3B, it can be seen that the attenuation is larger when two shield lines are inserted than when one shield line is inserted. By increasing the number of shield lines, a further shielding effect is obtained.
[0033]
In FIG. 4 to FIG. 6, when the results regarding the distance of the shield line, the width of the shield line, and the length of the shield line are viewed, the effect due to the presence of the shield line is similar to that in FIG. Appears remarkably.
[0034]
Summarizing the above, electromagnetic C-coupling (capacitive coupling) and M-coupling (inductive coupling) directly generated between the rear defogger 14 and the antenna wire 15 are released by the presence of the shield line 17, and the shield line 17 The C and M coupling with the rear defogger 14 becomes dense. Then, the electromagnetic wave noise that enters the power supply line and the like of the rear defogger 14 and is mixed therein is absorbed, and the noise induced in the antenna wire 15 is reduced. Therefore, electromagnetic wave noise at the time of radio reception is reduced, and it is possible to compensate for insufficient sensitivity particularly at the time of reception of weak AM broadcast.
[0035]
In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the gist of the present invention.
[0036]
The rear defogger pattern and the shield line pattern may be stacked one above the other with an insulating layer (glass or film) interposed therebetween, or alternatively, a method of alternately drawing a pattern in a comb shape may be adopted. Further, a shield line may be provided so as to surround the rear defogger.
[0037]
【The invention's effect】
As described above, according to the first aspect of the present invention, the electromagnetic wave noise at the time of radio reception is reduced, and the effect of compensating for the insufficient sensitivity at the time of weak AM broadcast reception can be achieved. In addition, there is an effect that it is simple, lightweight, and low in cost.
[0038]
According to the second aspect of the present invention, there is an effect that electromagnetic wave noise can be further reduced.
[0039]
According to the third aspect of the present invention, there is an effect that electromagnetic noise can be further reduced. Further, there is an effect that it is possible to contribute to prevention of a decrease in reception sensitivity.
[0040]
According to the present invention described in claim 4, there is an effect that electromagnetic noise can be further reduced.
[Brief description of the drawings]
FIG. 1 is a view showing one embodiment of a vehicle antenna structure according to the present invention, wherein (a) is a perspective view of a vehicle rear side, and (b) is a schematic view showing the vehicle antenna structure.
2A and 2B are diagrams showing another example of a shield line, wherein FIG. 2A is a schematic diagram of a wide type, FIG. 2B is a schematic diagram of a triple line type, and FIG. .
3A and 3B are graphs for verifying the effect of the number of shield lines by using an electromagnetic field simulation, wherein FIG. 3A is a graph for a transmission loss, and FIG. 3B is a graph for a shield effect.
4A and 4B are graphs for verifying the effect of the distance between shield lines using electromagnetic field simulation, wherein FIG. 4A is a graph for transmission loss and FIG. 4B is a graph for shield effect.
5A and 5B are graphs for verifying the effect of the width of a shield line using electromagnetic field simulation, wherein FIG. 5A is a graph for a transmission loss and FIG. 5B is a graph for a shield effect.
6A and 6B are graphs for verifying the effect of the length of the shield line using electromagnetic field simulation, wherein FIG. 6A is a graph for a transmission loss, and FIG. 6B is a graph for a shield effect.
FIG. 7 is a perspective view of a vehicle rear side showing a conventional vehicle antenna structure.
[Explanation of symbols]
11 Vehicle Antenna Structure 12 Vehicle 13 Rear Window Glass 14 Rear Defogger 15 Antenna Strip 16 Space 17 Shield Line 18 Bus Bar 19 Heater Wire 20, 21, 22 Shield Line

Claims (4)

A vehicle antenna structure including a rear window glass provided at a rear portion of a vehicle, an electrically heated rear defogger provided on the rear window glass, and an antenna wire provided on the rear window glass together with the rear defogger. So,
An antenna structure for a vehicle, wherein a shield line for electromagnetically isolating the rear defogger serving as a noise radiation source is provided in a space between the rear defogger and the antenna wire. The vehicle antenna structure according to claim 1,
An antenna structure for a vehicle, wherein the shield line is disposed close to the rear defogger and the antenna wire. The vehicle antenna structure according to claim 2,
When the distance between the shield line and the rear defogger is d1, and the distance between the shield line and the antenna wire is d2, the shield line is arranged to be d1 <d2. Characteristic vehicle antenna structure. The vehicle antenna structure according to any one of claims 1 to 3,
An antenna structure for a vehicle, wherein the shield line is formed to be wide along a direction between the rear defogger and the antenna wire.

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