JP3684844B2 - Glass antenna for automobile - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a glass antenna for an automobile suitable for receiving FM broadcast bands in Japan (76 to 90 MHz), FM broadcast bands in the United States (88 to 108 MHz), and AM broadcast bands (530 to 1630 kHz).
[0002]
[Prior art]
Conventionally, an electric heating type defogger having a plurality of heater wires and a bus bar for supplying power to these heater wires, and an antenna conductor capacitively coupled to the defogger are provided on a rear window glass plate of an automobile, 2. Description of the Related Art An automotive glass antenna in which a choke coil is connected between a bus bar and a DC power source is known.
[0003]
In this conventional example, capacitive coupling between the defogger and the antenna conductor is performed by the proximity of the antenna conductor and the substantially T-shaped defogger branch conductor provided on the highest heater wire.
[0004]
However, this conventional example has a drawback that the reception sensitivity does not become flat when receiving the FM broadcast band.
[0005]
[Problems to be solved by the invention]
The present invention aims to eliminate the above-mentioned drawbacks of the prior art, and provides an automotive glass antenna that has not been known so far.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems, and an electric heating type defogger having a heater wire and a bus bar for supplying power to the heater wire, and an antenna conductor capacitively coupled to the defogger are provided in an automobile. The defogger branch conductor provided in the defogger is provided in the rear window glass plate, and the capacitive coupling between the defogger and the antenna conductor is provided in the automotive glass antenna in which the choke coil is connected between the bus bar and the DC power source. And a proximity of the antenna conductor, and a defogger branch conductor is provided with a loop-shaped portion.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG. 2 are configuration diagrams of an embodiment of a glass antenna for an automobile according to the present invention. 1 and 2, reference numeral 1 denotes a rear window glass plate of an automobile, 2 denotes a heater wire, 3 denotes a defogger, 3a denotes a defogger branch conductor, 3b denotes a loop forming conductor provided on the defogger branch conductor, and 3c denotes each heater wire 2 4 is an antenna conductor, 5a and 5b are bus bars, 6 is a feeding point of the antenna conductor 4, 8 is a reactance circuit, 9 is a choke coil, 10 is a DC power source, and 11 is a capacitor for absorbing noise. . In the following description, unless otherwise specified, the direction refers to the direction on the drawing.
[0008]
In the automotive glass antenna of the present invention, the defogger 3 and the antenna conductor 4 are capacitively coupled, and a choke coil 9 is connected between the bus bar 5 b and the DC power supply 10. By this capacitive coupling, the defogger 3 apparently functions as a part of the antenna. Particularly for the AM broadcast band, the defogger 3 also functions as a part of the AM broadcast antenna, and the effective length of the AM broadcast antenna becomes longer, so that more received radio waves can be received and the sensitivity is improved.
[0009]
The choke coil 9 can insulate the heater wire 2 and the bus bars 5a and 5b from the vehicle body ground at high frequency, and the reception signal current of the radio broadcast band induced in the heater wire 2 and the bus bars 5a and 5b flows to the vehicle body ground. This reception signal current can be sent to a receiver (not shown) without leakage.
[0010]
The capacitive coupling between the defogger 3 and the antenna conductor 4 is performed by the proximity of the defogger branch conductor 3 a provided in the defogger 3 and the antenna conductor 4. Further, the defogger branch conductor 3a is provided with a loop-shaped portion. By this loop-shaped portion, the flatness of the sensitivity of the FM broadcast band can be adjusted, and the flatness can be improved. Here, the flatness of sensitivity refers to the difference between the highest sensitivity and the lowest sensitivity in a band such as an FM broadcast band.
[0011]
1 and 2, the loop-shaped portion is constituted by the defogger branch conductor 3a itself and the loop forming conductor 3b. The shape of the defogger branching conductor 3a is not particularly limited, but a substantially T-shape, a substantially L-shape or the like is usually used.
[0012]
Further, the shape of the loop forming conductor 3b is not particularly limited, and may be any shape as long as it forms a loop-shaped portion with a part or all of the defogger branching conductor 3a. As an example of the shape of the loop forming conductor 3b, a straight line, a curved line, a substantially L shape, or the like is usually used.
[0013]
The dimensions of the loop-shaped part are not particularly limited, but the horizontal (horizontal) dimension is preferably 30 to 200 mm, and the vertical (vertical) dimension is preferably 10 to 30 mm. When the frequency is within this range, the sensitivity of the FM broadcast band is usually improved by 0.5 d or more compared to the case outside this range.
[0014]
Further, the location of the defogger branch conductor 3a where the loop forming conductor 3b is provided is not particularly limited. However, it is preferably provided on the heater wire 2 side of the defogger branch conductor 3a. When the loop forming conductor 3b is provided on the heater wire 2 side of the defogger branch conductor 3a, an area where the sensitivity of the FM broadcast band is reduced is smaller than that provided on the antenna conductor 4 side of the defogger branch conductor 3a. 1.0d or more can usually be improved.
[0015]
1 and 2, one loop-shaped portion is provided. However, the present invention is not limited to this, and a plurality of loop-shaped portions may be provided on the defogger branch conductor 3a.
[0016]
Further, the location of the defogger 3 where the defogger branching conductor 3a is provided is not particularly limited. In FIG. 1, it is provided on the highest heater wire 2, and in FIG. 2, it is provided on the bus bar 5a.
[0017]
Capacitive coupling means that direct current is not transmitted / received but alternating current such as high-frequency current is transmitted / received, and is normally capacitively coupled with the distance between the defogger branch conductor 3a and the antenna conductor 4 within 50 mm.
[0018]
FIG. 3 is a configuration diagram of an embodiment different from FIGS. In FIG. 3, 14 is an antenna conductor different from the antenna conductor 4, 16 is a feeding point of the antenna conductor 14, 13a is a defogger branch conductor different from the defogger branch conductor 3a, and 13b is a loop formed on the defogger branch conductor 13a. Conductor. The antenna conductor 14 and the defogger 3 are capacitively coupled.
[0019]
In the glass antenna for an automobile shown in FIG. 3, diversity reception is performed by selecting the stronger one of the reception signals at the feeding point 6 and the feeding point 16 and sending it to the receiver.
[0020]
1, 2, and 3, the position of the rear glass plate 1 on which the antenna conductor 4 is provided is provided where the antenna conductor is provided at the upper, lower, left, and right margins from the defogger 3 of the rear glass plate 1. However, the positions are not limited to the positions shown in FIGS. 1, 2, and 3.
[0021]
Further, the number of antenna conductors provided on the rear glass plate 1 other than the antenna conductor 4 and the antenna conductor 14 is not limited. The short-circuit line 3c shown in FIG. 1 and FIG. 3 is provided as necessary by short-circuiting each heater line 2, and has a function of adjusting the impedance of the defogger 3.
[0022]
【Example】
"Example 1 (Example)"
A glass antenna for an automobile as shown in FIG. 1 was manufactured using a rear window glass plate of the automobile. The dimensions of each part are as follows.
[0023]
1.0 mm between the defogger branch conductor 3a and the antenna conductor 4;
The horizontal dimension of the loop-shaped part 50 mm,
23mm in the vertical dimension of the loop-shaped part,
The lateral dimension (maximum width) of the defogger branch conductor 3a is 405 mm,
The conductor width of the antenna conductor 4 is 0.7 mm,
Defogger branch conductor 3a conductor width 0.7 mm,
The conductor width of the loop forming conductor 3b is 0.7 mm.
[0024]
The frequency-sensitivity characteristic of the US FM broadcast band is shown by a solid line in FIG. Also, the AM broadcast band could be received well.
[0025]
"Example 2 (comparative example)"
An automotive glass antenna having the same specifications as in Example 1 was produced except that the loop forming conductor 3b was not provided. The frequency-sensitivity characteristics of the US FM broadcast band are shown by dotted lines in FIG.
[0026]
【The invention's effect】
According to the present invention, it is possible to adjust the flatness of the sensitivity of the FM broadcast band, and the flatness can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of an automotive glass antenna of the present invention. FIG. 2 is a block diagram of another embodiment. FIG. 3 is a block diagram of another embodiment. , Frequency-sensitivity characteristics diagram of FM broadcasting band in the US 【Explanation of symbols】
1: automotive rear window glass plate 2: heater wire 3: defogger 3a: defogger branch conductor 3b: loop forming conductor 3c provided on the defogger branch conductor: short-circuit wire 4 for short-circuiting each heater wire 2: antenna conductors 5a, 5b : Bus bar 6: Feed point 8 of antenna conductor 4: Reactance circuit 9: Choke coil 10: DC power supply 11: Capacitor

Claims (1)

An energization heating type defogger having a heater wire and a bus bar for supplying power to the heater wire, and an antenna conductor capacitively coupled to the defogger are provided on a rear window glass plate of the automobile. In an automotive glass antenna with a choke coil connected between,
The capacitive coupling between the defogger and the antenna conductor is performed by the proximity of the defogger branch conductor provided in the defogger and the antenna conductor,
A glass antenna for an automobile, wherein the defogger branching conductor is provided with a loop-shaped portion.

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