JPH11340720A - Glass antenna device for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide device in which a choke coil can be made compact, and a long wave broadcast band can be received with a low noise by connecting a band elimination filter circuit between a choke coil and a DC power source, or between a bus bar and the choke coil. SOLUTION: A glass board 1 is provided with an antenna conductor 4, and the antenna conductor 4 is made adjacent to a branch line 3a of a defogger 3 with a prescribed interval so that the capacity coupling of the antenna conductor 4 and the defogger 3 can be attained. Then, a choke coil 9 is connected between bus bars 5a and 5b and a DC power source 10 in this antenna device. Moreover, a band elimination filter circuit 15 is connected between the choke coil 9 and the DC power source 10, or between the bus bar 5b and the choke coil 9. Thus, it is possible to prevent any noise currents from flowing from a body or the DC power source 10 to the defogger 3 by the choke coil 9 and the band elimination filter circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass antenna device for automobiles which is suitable for receiving a long-wave broadcasting band (LW band) (150 to 280 kHz) of radio broadcasting and has excellent productivity.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, an automotive glass antenna device for receiving LW band has been used. In the conventional example shown in FIG. 5, the antenna conductor 4 and the defogger 3 are capacitively coupled. In addition, bus bar 5
By connecting the choke coil 9 between the DC power supply 10 and the DC power supply 10 and increasing the impedance of the choke coil 9 in a broadcast band such as the LW band, the DC current from the DC power supply 10 to the defogger 3 flows. The reception signal current in the broadcast band is cut off.

In this way, the choke coil 9 insulates the defogger 3 from the vehicle body (earth) at a high frequency,
The noise current from the vehicle body and the DC power supply 10 is prevented from flowing to the defogger 3 as much as possible, and the influence of the noise current of the defogger 3 does not affect the antenna conductor 4.

However, in order to increase the impedance of the choke coil 9 in the LW band, the inductance of the choke coil 9 must be 5 to 10 mH or more, and a large current must flow through the defogger 3. Therefore, the current capacity of the choke coil 9 needs to be increased, and a very large choke coil 9 is required, resulting in poor productivity.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and to provide a glass antenna device for a vehicle which has not been known hitherto.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an electric heating type defogger having a heater wire and a bus bar for supplying power to the heater wire, and a capacity of the defogger. The coupled antenna conductor is provided on the rear window glass plate of the automobile, and a choke coil is connected between the bus bar and the DC power supply. Alternatively, there is provided a glass antenna device for an automobile, wherein a band elimination filter circuit is connected between a bus bar and a choke coil.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a basic configuration diagram of a glass antenna device for a vehicle according to the present invention. In FIG. 1, 1 is a glass plate of a rear window of an automobile, 2 is a heater wire, 3 is a defogger, 3
a is a branch line, 4 is an antenna conductor, 5a and 5b are bus bars,
6 is a feeding point of the antenna conductor 4, 7 is an antenna peripheral circuit,
9 is a choke coil, 10 is a DC power supply, 15 is a band elimination filter circuit, and 20 is a receiver.

An antenna conductor 4 is provided in a margin above the defogger 3 of the glass plate 1. Antenna conductor 4
And the branch line 3a of the defogger 3 are close to each other with a predetermined space therebetween, so that the antenna conductor 4 and the defogger 3 do not transmit and receive DC current between them.
The transmission and reception of the high-frequency current are capacitively coupled so as to be performed.

Meanwhile, a noise current flows from the vehicle body and the DC power supply 10 to the defogger 3. This noise current is generated by an engine or the like. In the LW band, the antenna conductor 4 is affected by the noise current flowing through the defogger 3 due to the capacitive coupling, and the S / N ratio deteriorates.

In the present invention, the choke coil 9 is connected between the bus bars 5a and 5b and the DC power supply 10. further,
In the present invention, the band elimination filter circuit 1 is provided between the choke coil 9 and the DC power supply 10 (FIG. 1) or between the bus bar 5b and the choke coil 9 (not shown).
5 is connected. This is to prevent a noise current affecting the LW band from flowing from the vehicle body or the DC power supply 10 to the defogger 3 by the choke coil 9 and the band elimination filter circuit 15.

Here, the band elimination filter circuit 15 is a filter circuit having a frequency characteristic for attenuating frequencies in a frequency range between one frequency (for example, 150 kHz) and a higher frequency (for example, 280 kHz). In addition, the center frequency of the band elimination filter circuit 15 in the present invention refers to the most attenuated frequency in the sandwiched frequency range.

The center frequency of the band elimination filter circuit of the present invention is preferably 150 to 280 kHz. This is to prevent a noise current affecting the LW band from flowing from the vehicle body into the defogger 3 as effectively as possible.

The inductance of the choke coil 9 is 0.
3-1.5 mH is preferred. When the pressure is 0.3 mH or less, it is difficult to contribute to the improvement of the sensitivity in the LW band.
This is because productivity and compactness cannot be attained when H is exceeded. The antenna peripheral circuit 7 includes an impedance matching circuit, a preamplifier circuit, a resonance circuit, and the like.
There is no particular limitation.

FIG. 3 is a circuit diagram of an embodiment of a band elimination filter circuit used in the glass antenna device for a vehicle according to the present invention. In FIG. 3, C ₁ , C ₂ ,
C ₃ denotes a capacitor, R ₁ is the resistance, L ₁ is the inductance. The capacitors C ₁ , C ₂ , C ₃ have 0.1 to 1
Generally, 0 μF, 10 Ω to 100 KΩ for the resistor R _1, and 0.1 to 10 μH for the inductance L ₁ are used.

Further, a low-pass filter circuit may be connected between the choke coil 9 and the band elimination filter circuit 15 to improve the S / N ratio in the LW band.

[0016]

Example 1 (Example) A glass antenna device for a vehicle as shown in FIG. 1 was manufactured using a rear window glass plate of a vehicle. Band elimination filter circuit 1
5 used the circuit shown in FIG. The dimensions and constants of each part are as follows.

A capacitor C ₁ 2.2 μF, a capacitor C ₂ 0.18 μF, a capacitor C ₃ 1.8 μF, a resistance R ₁ 1.2 Ω, an inductance L ₁ 4.7 μH, a choke coil 9 0.82 mH, and a point on the bus bar 5 b FIG. 4 shows a noise voltage-frequency characteristic diagram at the time.

Example 2 (Comparative Example) A high-frequency glass antenna device for an automobile shown in FIG. 5 was manufactured. Except that the band elimination filter circuit 15 was not provided, the specifications were exactly the same as in Example 1. FIG. 2 shows a noise voltage-frequency characteristic diagram at one point on the bus bar 5b.

[0019]

According to the present invention, a very large choke coil is not required, the volume ratio of the choke coil can be reduced to 1/2 or less, and the weight ratio can be reduced to 1/3 or less, and the choke coil can be made compact. Further, the LW band can be received with low noise, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a glass antenna device for an automobile of the present invention.

FIG. 2 is a noise voltage-frequency characteristic diagram of Example 2.

FIG. 3 is a circuit diagram of an embodiment of a band elimination filter circuit used in the glass antenna device for a vehicle according to the present invention.

FIG. 4 is a noise voltage-frequency characteristic diagram of Example 1.

FIG. 5 is a basic configuration diagram of a conventional example.

[Explanation of symbols]

 1: glass plate of rear window of automobile 2: heater wire 3: defogger 3a: branch line 4: antenna conductor 5a, 5b: bus bar 6: feeding point of antenna conductor 4 7: antenna peripheral circuit 9: choke coil 10: DC power supply 15: Band elimination filter circuit 20: Receiver

Claims (1)

[Claims] 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 on a rear window glass plate of an automobile. In a glass antenna apparatus for an automobile in which a choke coil is connected between a choke coil and a DC power supply, a band elimination filter circuit is connected between the choke coil and the DC power supply or between the bus bar and the choke coil. A glass antenna device for an automobile, characterized in that: