JP2000188507A - Glass antenna system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass antenna system for vehicle with an excellent anti- static electricity characteristic that can receive both AM and FM broadcast bands excellently. SOLUTION: Series resonance is produced in a coil 31 placed between an antenna conductor 3 and a receiver 7, parallel resonance is caused in a coil 32 placed between a defogger 90 and a car body earth, a high frequency choke coil 52 is connected between the antenna conductor 3 and the defogger 90 and serge voltage absorbing elements 80, 81 are connected between a signal line and the car body earth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a long wave broadcasting band (15
0-280 kHz), medium wave broadcasting band (530-1630 kHz)
Hz), shortwave broadcasting band (2.3-26.1 MHz), FM
Broadcasting band (76-90 MHz (Japan)), FM broadcasting band (8
8-108MHz (USA), TV VHF band (90-
108MHz, 170-222MHz) and TV UH
The present invention relates to a glass antenna device for a vehicle that is suitable for reception in the F band (470 to 770 MHz), has high reception sensitivity, has low noise, and has high productivity.

[0002]

2. Description of the Related Art Conventionally, a glass antenna device for a vehicle shown in FIG. 4 has been proposed as a glass antenna device for a vehicle in which reception sensitivity is improved by utilizing resonance (Japanese Utility Model Publication No. 4-5307).
0). The so-called U-shaped defogger 90 shown in FIG.
Then, on the left side of the defogger 90, the lower side bus bar 15a,
An upper bus bar 15b is provided. Lower side bus bar 15a
Is connected to the vehicle body ground, and the upper bus bar 15b is connected to the anode of the DC power supply 10. The supplied current flows from the upper bus bar 15b through the right bus bar 15c to the lower bus bar 15a in a U-shape.

In the conventional example shown in FIG. 4, bus bars 15a, 15b
The choke coil 9 is connected between the DC power supply 10 and the DC power supply 10 for the defogger 90 to increase the impedance of the choke coil 9 in a high frequency band.
A DC current flows from the defogger 90 to the defogger 90 but cuts off a current in a high frequency band such as a broadcast band.
Is used as an antenna.

[0004] In the medium wave broadcasting band, defoggers 90
And a coil 71, and a coil 72, a capacitor 73, and a resistor 74 allow a reception signal in the medium-wave broadcasting band to pass. Reference numeral 11 denotes a noise cut capacitor. In the conventional example of FIG. 4, by adopting such a configuration, the receiving sensitivity is improved and the noise is reduced.

[0005] However, in the conventional example shown in FIG.
The stray capacitance of the cable connecting 0 and the receiver is the main factor causing parallel resonance, and the parallel resonance frequency exists in the medium-wave broadcasting band, so that the S / N ratio is poor. And the receiving sensitivity was not sufficient.

Further, the defogger 90 is connected to the medium wave broadcasting band and the F band.
When the antenna is used for the M broadcast band, the defogger 90
However, even if the shape is optimal for the reception of the medium wave broadcast, there is a problem that the reception sensitivity and the directivity of the FM broadcast are insufficient at the time of the reception of the medium wave broadcast. Further, there is a problem that the resistor 74 is destroyed due to a surge voltage generated by static electricity.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to newly provide a glass antenna device for a vehicle excellent in high receiving sensitivity, low noise, good productivity and surge voltage resistance. provide.

[0008]

According to the present invention, there is provided an electrically heated defogger having a heater wire and a bus bar, and an antenna conductor provided on a rear window glass plate of the vehicle. And / or a glass antenna device for a vehicle in which a choke coil is connected between a bus bar and a vehicle body ground, comprising a first coil and a second coil, wherein the impedance of the antenna conductor and the first coil And a second resonance including the impedance of the defogger and the inductance of the second coil as a resonance element, and a first reception frequency band. And a reception signal of a second reception frequency band higher than the first reception frequency band are transmitted from the antenna conductor to the receiver, and the first resonance The oscillation frequency and the resonance frequency of the second resonance are frequencies at which the sensitivity of the first reception frequency band is improved, and the reception signal of the second reception frequency band is blocked or interposed between the antenna conductor and the defogger. An attenuating filter circuit is electrically connected, the filter circuit includes a high-frequency choke coil, and a first coil is electrically connected between the antenna conductor and the receiver via wiring and / or circuit elements. A second coil is electrically connected between the defogger and the vehicle body ground via wiring and / or a circuit element, and a line between the first coil and the antenna conductor is connected to the vehicle body ground. A surge voltage absorbing element is electrically connected between the defogger and the vehicle body ground through a wiring and / or a circuit element. To provide a glass antenna device for a vehicle, characterized by being electrically connected.

[0009]

FIG. 1 shows a rear window glass plate 1 of an automobile.
FIG. 1 is a basic configuration diagram of a glass antenna device for a vehicle of the present invention, using FIG. In FIG. 1, 42 is a bypass capacitor, 45 and 48 are damping resistors, 47 is a resistor for reducing vehicle noise such as engine noise, 50 and 51 are DC cut capacitors, and 80 and 81 are surge voltage absorbing elements. , 91 are feeding points provided at the leading end of the lead wire connected to the defogger 90. In the following, unless otherwise specified, the direction refers to the direction on the drawing.

FIG. 3 is an equivalent circuit diagram for explaining the principle of the apparatus shown in FIG. However, the resistance 45, the resistance 47 and the resistance 4
Reference numeral 8 is omitted for simplicity of description, and the location of the resistor 45 is open, and the locations of the resistors 47 and 48 are short-circuited.

In FIG. 3, E1 is the voltage power supply of the antenna conductor 3, E2 is the voltage power supply of the defogger 90, 33 is the stray capacitance to the ground of the antenna conductor 3 (hereinafter, the stray capacitance to the ground is simply referred to as the stray capacitance), and 34 is This is the stray capacitance of the defogger 90. When the antenna conductor 3 and the defogger 90 are close to each other and capacitively coupled, the proximity capacitance due to this capacitive coupling is connected in parallel with the high-frequency choke coil 52.

The antenna conductor 3 is preferably used for receiving a second reception frequency band (hereinafter, referred to as a high frequency band) higher in frequency than the first reception frequency band (hereinafter, referred to as a low frequency band). It is preferable to set the conductor length and the conductor shape so as to obtain a suitable reception performance in a high frequency band.

The antenna conductor 3 and the defogger 90 can be used for medium-wave broadcasting, FM broadcasting, short-wave broadcasting, long-wave broadcasting, television VHF, television UHF, and telephone reception. For example, in general, a low frequency band is a medium-wave broadcast band, and a high frequency band is one or more of an FM broadcast band, a television VHF band, and a television UHF band.

In the present invention, two resonances occur to improve the receiving sensitivity. Regarding the first resonance, the impedance of the antenna conductor 3 and the inductance of the first coil 31 are included as resonance elements.

The impedance of the antenna conductor 3 is mainly composed of the stray capacitance 33, and the impedance of the antenna conductor 3 means the impedance when the antenna conductor 3 is viewed from the feeding point 4 side.

Further, a capacitance component may be connected in parallel between the stray capacitance 33 and the vehicle body ground to adjust the resonance frequency of the first resonance. This capacitance component can also be a resonance element of the first resonance.

Since the antenna conductor 3 and the defogger 90 are electrically connected, the first resonance is affected by the impedance of the defogger 90 and can be a resonance element of the first resonance.

The impedance of the defogger 90 mainly consists of the stray capacitance 34, and the impedance of the defogger 90 refers to the impedance when the defogger 90 is viewed from the feeding point 91. Further, the stray capacitance of the wiring around the first coil 31, the stray capacitance of a cable connected between the glass antenna and the receiver, and the like also affect the first resonance. It can be.

A new circuit element may be provided inside the resonance circuit 6 to perform impedance matching between the antenna conductor 3 and the receiver. The first coil 31 usually has 10 μH
〜1 mH is used.

Regarding the second resonance, the second coil 32
And the inductance of the choke coil 9 and the impedance of the defogger 90 are included as resonance elements. As the second coil 32, a coil of about 10 μH to 1 mH is usually used.

In FIG. 1, the first resonance is a series resonance,
The second resonance is a parallel resonance. In the present invention, this is preferable from the viewpoint of improving sensitivity. However, in the present invention, the first resonance may be a parallel resonance, and the second resonance may be a series resonance.

The operation of the capacitor 51 will be described. If the capacitor 51 is not provided and the portion of the capacitor 51 is short-circuited, the DC current flowing through the defogger 90 flows into the second coil 32, so that the second coil 32
The current capacity of the defogger 90 must be increased, and the DC current flowing through the defogger 90 flows into the vehicle body ground via the coil 32, so that the current is wasted. Therefore, the capacitor 51 is not essential but is preferably provided.

In FIG. 1, the capacitor 51 is connected between the feeding point 91 and the second coil 32, and is connected to the feeding point 91.
Is connected to the bus bar 5b, the capacitor 51 includes the inductance of the bus path and the impedance of the defogger 90 as resonance elements.

In FIG. 1, a high-frequency choke coil 52, which is an inductance element, separates the antenna conductor 3 and the defogger 90 from each other in a high frequency band in a high frequency range, and does not change the effective length of the conductor of the antenna conductor 3. It has the function of improving reception sensitivity in the high frequency band.

If the high-frequency choke coil 52 is not provided and the high-frequency choke coil 52 is short-circuited, the choke coil 9 or the second coil 32 has a low self-resonant frequency and a low capacitance in the high frequency band. Since the received signal in the high frequency band excited in the antenna conductor 3 leaks to the vehicle body ground, the high frequency choke coil 52 is provided to prevent this. In other words, the high-frequency choke coil 52 has a function as a filter circuit that passes frequencies in the low frequency band and cuts off or attenuates frequencies in the high frequency band.

When the low frequency band is a medium-wave broadcasting band and the high frequency band is one or more of an FM broadcasting band, a television VHF band and a television UHF band, a high-frequency choke coil 52
The one having an inductance value in the range of 0.1 to 100 μH is usually used. If the high-frequency choke coil 52 is set to 0.
In the case of the range of 1 to 100 μH, the sensitivity in the high frequency band is improved by 0.2 dB or more as compared with the case where the range is outside the range of 0.1 to 100 μH.

When the low frequency band is the medium frequency broadcasting band and the high frequency band is the FM broadcasting band of Japan or the United States, the high frequency choke coil 52 has an inductance value in the range of 0.3 to 20 μH. Is preferred. In the range of 0.3 to 20 μH, the sensitivity of the FM broadcast band is improved by 0.5 dB or more as compared with the case outside the range of 0.3 to 20 μH. Further, the high-frequency choke coil 52 is 0.8 to 4.8 μH
It is more preferable that the inductance value is in the range of The high-frequency choke coil 52 has a sensitivity of 2 dB or more in the FM broadcast band in the range of 0.8 to 4.8 μH, as compared with the case outside the range of 0.8 to 4.8 μH.

In FIG. 1, it is preferable that the antenna conductor 3 and the defogger 90 are not capacitively coupled as much as possible. In the case of capacitive coupling, a reception signal in a high frequency band excited in the antenna conductor 3 easily leaks to the vehicle body ground via the defogger 90 and the choke coil 9. In order to minimize the capacitive coupling between the antenna conductor 3 and the defogger 90, it is preferable that the shortest distance between the antenna conductor 3 and the defogger 90 be 10 mm or more. When the shortest interval is 10 mm or more, the sensitivity in the high frequency band is improved by 0.5 dB or more compared to the case where the shortest interval is less than 10 mm. More preferably, the shortest interval is 20 mm or more. When the shortest interval is 20 mm or more, the sensitivity in the high frequency band is improved by 0.5 dB or more as compared with the case where the shortest interval is less than 20 mm.

A surge voltage absorbing element 80 is electrically connected between the line between the first coil 31 and the antenna conductor 3 and the vehicle body ground via wiring. Further, a surge voltage absorbing element 81 is provided between the defogger 90 and the vehicle body ground.
Are electrically connected via wiring. This is to protect the resonance circuit 6 from surge voltage such as static electricity. Although the surge voltage absorbing elements 80 and 81 and the circuit elements such as resistors are not connected in series in FIG.
1 and a circuit element such as a resistor may be connected in series.

In other words, the surge voltage absorbing element 80 is electrically connected between the line between the first coil 31 and the antenna conductor 3 and the vehicle body ground via wiring and / or circuit elements. A surge voltage absorbing element 81 is electrically connected between the defogger 90 and the vehicle body ground via wiring and / or circuit elements.

The charges of the surge voltage enter from the antenna conductor 3 and the defogger 90. The charge of the surge voltage entering from the antenna conductor 3 flows through the feed point 4 to the vehicle body ground via the surge voltage absorbing element 80, and does not reach the resonance circuit 6. On the other hand, the electric charge of the surge voltage entering from the defogger 90 flows through the feeding point 91 to the vehicle body ground via the surge voltage absorbing element 81, and does not reach the resonance circuit 6. As described above, by adopting the circuit configuration as shown in FIG. 1, the electric charge of the surge voltage flows to the vehicle body ground, and the resonance circuit 6 can be protected.

As the surge voltage absorbing elements 80 and 81,
An element that has a function of absorbing surge voltage such as static electricity and has an interval between two electrodes of several tens of μm, and when a surge voltage is applied between the two electrodes, it is discharged to absorb the surge voltage. (Electron emission mechanism element), a Zener diode, a thyristor and the like can be used, and among them, a field electron emission mechanism element is preferable. This is because the value of the capacitance of the field electron emission mechanism element is very small, usually several pF, so that it is difficult to lower the sensitivity. On the other hand, the capacitance of a semiconductor element such as a Zener diode and a thyristor is usually as large as several tens of pF, so that the sensitivity is easily reduced.

The capacitance of the surge voltage absorbing element is preferably 10 pF or less. The capacitance value is 10 pF
When it is less than or equal to 10 pF, sensitivity in a high frequency band such as an FM broadcast band is usually improved by 1 dB or more as compared with the case where it is more than 10 pF. A more preferred range is 5 pF or less. When the value of the capacitance is 5 pF or less, the sensitivity in the high frequency band such as the FM broadcast band is usually improved by 1 dB or more as compared with the case where the capacitance is more than 5 pF. A particularly preferred range is 2 pF
It is as follows. When the value of the capacitance is 2 pF or less, the sensitivity in the high frequency band such as the FM broadcasting band is usually improved by 1 dB or more as compared with the case where the capacitance is more than 2 pF.

In FIG. 2, the glass antenna device for a vehicle shown in FIG. 1 is developed to perform diversity reception. In FIG. 2, 53 is a capacitor, 60 is a high-frequency choke coil, t ₁ is a first input of the receiver 7, and t ₂ is a second input of the receiver 7. The receiver 7 selects a stronger received signal in the high frequency band between the first input t ₁ and the second input t ₂ .

The capacitor 53 is provided as needed.
It has a function of blocking or attenuating a received signal in a low frequency band. The capacitance value of the capacitor 53 is preferably in the range of 10 to 150 pF, and more preferably in the range of 20 to 70 pF.
When the low frequency band is the medium wave broadcasting band, when the capacitance value of the capacitor 53 is in the range of 10 to 150 pF,
Compared to the case outside the range of 150 pF, the sensitivity of the medium wave broadcast band is improved by 1 dB or more. When the capacitance value of the capacitor 53 is 2
When the range is 0 to 70 pF, the sensitivity of the medium-wave broadcasting band is improved by 1 dB or more compared to the case where the range is outside the range of 20 to 70 pF.

When the second coil 32 has a capacitance in a high frequency band such as the FM broadcast frequency among the broadcast frequencies, the received signal leaks to the vehicle body ground, and
Reception sensitivity drops. To prevent this, the second coil 3
2, a high-frequency choke coil 60 may be connected in series. The high-frequency choke coil 60 usually has 0.1 to 1
About 00 μH is used.

In the glass antenna device for a vehicle shown in FIG. 2, the high-frequency choke coils 12a and 12b are preferably connected between the bus bar and the choke coil 9. Not used in the apparatus of FIG. 1, for using the received signal of the high frequency band excited in the defogger 90 with a second input t _2, the high-frequency choke coils 12a, high frequency excited in the defogger 90 at 12b This is to prevent the reception signal of the band from leaking to the vehicle body ground.

In FIG. 2, the second input t ₂ of the receiver 7 is taken out of the resonance circuit 6 (the left end of the capacitor 53 is connected to the inside of the resonance circuit 6). However, the location from which the second input t ₂ is extracted is not limited to the inside of the resonance circuit 6, and may be extracted from any location of the defogger 90.
Further, an antenna conductor different from the antenna conductor 3 may be provided in a blank portion below the defogger 90 to perform diversity reception between the first input t ₁ and another antenna conductor. As described above, the protection effect of the surge voltage absorbing elements 80 and 81 on the resonance circuit 6 when a surge voltage is generated is described with reference to the vehicle glass antenna device of FIG. 2 and the vehicle glass antenna device of FIG. The same is true.

In the present invention, two resonances are generated because only one resonance cannot cover a wide reception frequency band. Therefore, in the present invention, it is desirable to divide the low frequency band into two substantially at the center frequency and to share each of the two resonances with two resonances to achieve flat reception sensitivity. Here, flattening the receiving sensitivity means reducing the difference between the highest receiving sensitivity and the lowest receiving sensitivity within a band such as a low frequency band.

Further, the resonance frequency of the first resonance and the resonance frequency of the second resonance are set to frequencies that improve the sensitivity in the low frequency band. However, the resonance frequency of the first resonance exists between the frequency 1.5 times the highest frequency f _LH of the low frequency band and the substantially center frequency of the low frequency band, and the lowest resonance frequency of the low frequency band. be present resonance frequency of the second resonance between the substantially center frequency of 0.6 times the frequency and low frequency bands of the frequency f _LL is preferable in terms of planarization of the reception sensitivity. Outside of this range, it is difficult to make the difference between the highest reception sensitivity and the lowest reception sensitivity in the low frequency band usually less than about 10 dB, and the flatness of the reception sensitivity in the low frequency band is poor.

Further, it is preferable that the resonance frequency of the first resonance exists in a low frequency band in view of improvement of reception sensitivity. When the signal is present in the low frequency band, the reception sensitivity in the entire low frequency band is usually 10 compared to when it is not present.
Improve by about dB.

Therefore, in order to improve both the flatness and the reception sensitivity, the resonance frequency of the first resonance exists between f _LH and the substantially center frequency of the low frequency band, and f _LL
It is more preferable that the resonance frequency of the second resonance exists between the frequency 0.6 times of the above and the substantially center frequency of the low frequency band.

When the first resonance is a series resonance, the resonance frequency of the first resonance is preferably higher than the substantially center frequency of the low frequency band. When the second resonance is a parallel resonance, the resonance frequency of the second resonance is preferably lower than the substantially center frequency of the low frequency band. When the second resonance is the parallel resonance, the reception sensitivity is significantly reduced in a range lower than the resonance frequency of the parallel resonance.

The bypass capacitor 42 is provided as needed, and has a function of transmitting a high frequency band to the receiver. For example, when the low-frequency band is the medium-wave broadcast band and the FM broadcast reception is also performed, the reception signal of the FM broadcast band is passed by the bypass capacitor 42.

Further, a lead wire for supplying a DC current from the DC power supply 10 to the defogger 90 picks up a vehicle noise such as an engine noise and causes a deterioration of the S / N ratio. The resistor 47 is provided as needed, and has a function of preventing the deterioration of the S / N ratio. In particular, it has a function of preventing the deterioration of the S / N ratio in the low frequency band of the medium wave broadcasting band. That is, the resistor 47 has a function of reducing vehicle noise such as engine noise.

The resistance value of the resistor 47 is preferably 10 Ω to 1 kΩ, and more preferably 50 to 500 Ω. When the low frequency band is set to the medium wave broadcasting band, the resistance value of the resistor 47 is set to 10Ω to 1 kΩ.
In this case, the S / N ratio of the medium wave broadcasting band is improved by 1 dB or more as compared with the case where the value is out of the range of 10Ω to 1 kΩ. When the resistance value of the resistor 47 is 50 to 500Ω, 50
S of the medium wave broadcasting band
The / N ratio is improved by 1 dB or more.

As described above, in FIGS. 1 and 2, the capacitors 42, 50, and 51 and the resistors 45, 47, and 48 are provided as necessary and can be omitted.
Omission and the omission of the resistor 45 are to be open, and omission of the capacitors 50 and 51 and omission of the resistors 47 and 48 are to a short circuit.

In FIG. 2, a choke coil 9 is provided between bus bars 5a, 5b and DC power supply 10 for defogger 90.
By inserting the high-frequency choke coils 12a and 12b and increasing the impedance of the choke coil 9 and the high-frequency choke coils 12a and 12b in the broadcast band, a DC current flows from the DC power supply 10 to the defogger 90, but a current in the broadcast band. Is trying to shut off.

In this way, the defogger 9 is formed by the choke coil 9 and the high-frequency choke coils 12a and 12b.
The heater wire 2 and the bus bars 5a and 5b can be insulated from the vehicle body ground at a high frequency, and the reception current of the broadcasting band induced by the defogger 90 can be prevented from flowing to the vehicle body ground. Can be sent to the machine. The choke coil 9 is usually used at a pressure of about 0.1 to 10 mH.

The high-frequency choke coils 12a and 12b and the high-frequency choke coil 60 have high impedance in a high frequency band such as an FM broadcast band among broadcasting bands, and usually use a solenoid or a magnetic core. They have an inductive inductance in and around high frequency bands, such as the FM broadcast band.

The choke coil 9 has a low self-resonant frequency in a high frequency band such as the FM broadcast band, and when the capacitance appears, the high-frequency choke coils 12a and 12b take the place of it. High frequency choke coils 12a, 12b
Is generally used in the range of about 0.1 to 100 μH. For the same reason, when the second coil has a low self-resonant frequency in a high frequency band such as the FM broadcast band and the capacitance appears, the high-frequency choke coil 60 takes over.

If the choke coil 9 does not show capacitance in a high frequency band such as the FM broadcast band, the high-frequency choke coils 12a and 12b are unnecessary. in short,
In the case of receiving only a low frequency band such as a medium-wave broadcast band, the high-frequency choke coils 12a and 12b are usually unnecessary, and only the choke coil 9 is sufficient, and only a high frequency band such as the FM broadcast band is received. If so, only the high-frequency choke coils 12a and 12b may be used. Further, even when both the low frequency band and the high frequency band are received, the choke coil 9, the high-frequency choke coil 12
If there is a choke coil that satisfies both functions a and 12b, only such a choke coil may be used.

The defogger 90 shown in FIGS. 1 and 2 has a so-called substantially U-shape.
0 is not limited to this, and a so-called substantially U-shaped defogger 90 as shown in FIG. 4 can be used in the present invention.

The antenna conductor 3 may be provided anywhere in the margin above, below, to the left of, or to the right of the defogger 90 of the window glass plate 1 and is not limited to the position shown in FIG. The number of antenna conductors provided on the window glass plate 1 is not limited as long as it is two or more.

In the present invention, the number of antenna conductors provided on the vehicle other than the antenna conductor 3 is not limited. Further, diversity reception may be performed with another antenna device such as the glass antenna device and the pole antenna of the present invention or another glass antenna device.

The antenna conductor 3 and the defogger 90 shown in FIG. 1 are not provided with an auxiliary antenna conductor. However, for the purpose of phase adjustment and directivity adjustment, a substantially T-shaped or substantially L-shaped auxiliary antenna conductor may be attached to the conductor pattern or the feeding point of these antenna conductors.

[0057]

Example 1 (Example) A glass antenna device as shown in FIG. 1 was manufactured using a rear window glass plate of an automobile. For the high-frequency choke coil 52, the inductance value was 2.2 μH, the self-resonant frequency was 90 MHz, and the other circuit constants were as follows. As the surge voltage absorbing elements 80 and 81, DSP-141N (capacitance: 1 pF), which is a field electron emission mechanism element manufactured by Mitsubishi Materials Corporation, was used.

First coil 31 = 150 μH, second coil 32 = 560 μH, bypass capacitor 42 = 22 pF, resistance 45 = 15 kΩ, resistance 47 = 270Ω, resistance 48 = 220Ω, capacitors 50, 51 = 1000 pF, choke coil 9 = 1.6 mH, stray capacitance of defogger 90 = 100 pF.

The conductor length and the shape of the antenna conductor 3 were adjusted so that the medium wave broadcast band and the FM broadcast band could be received. The distance between the lower part of the antenna conductor 3 and the uppermost line of the heater wire 2 is set to 2
The length was increased to 1 mm. In this case, the antenna conductor 3 and the defogger 90 were slightly capacitively coupled.

FIG. 5 is a frequency-sensitivity characteristic diagram of a medium-wave broadcasting band. FIG. 5 shows the relative sensitivity when the sensitivity of the pole antenna having a length of 910 mm is set to 0 dB. First
The resonance frequency of the resonance (series resonance) was 1450 kHz, and the resonance frequency of the second resonance (parallel resonance) was 480 kHz. FIG. 6 shows the frequency-sensitivity characteristics of the FM broadcast band.

In order to generate a surge voltage,
An electric charge was applied to the capacitor C having a capacitance of 0 pF at 15000 V, and the following application test was performed using a series circuit F in which the capacitor C and a resistor having a value of 330Ω were connected in series. Here, regarding the series circuit F, the cathode of the capacitor C
A resistor of 0Ω is connected in series, the anode of the capacitor C is used as the anode of the series circuit F, and the end of the resistor opposite to the end of the resistor connected to the capacitor C is used as the cathode of the series circuit F. explain.

(1) The anode of the series circuit F is connected to the antenna conductor 3
And the cathode of the series circuit F is connected to the vehicle body ground to discharge the electric charge stored in the capacitor C. (2) Connect the cathode of the series circuit F to the antenna conductor 3 and connect the anode of the series circuit F to the vehicle body ground to discharge the electric charge stored in the capacitor C. (3) Connect the anode of the series circuit F to the defogger 90 and connect the cathode of the series circuit F to the vehicle body ground to discharge the electric charge stored in the capacitor C. (4) Connect the cathode of the series circuit F to the defogger 90 and connect the anode of the series circuit F to the vehicle body ground to discharge the electric charge stored in the capacitor C.

The tests (1) to (4) were conducted for 50 tests each.
After repeating 0 times, the resistance values were measured in order to determine whether or not the resistances 47 and 48 had deteriorated. However, the resistance values of both were not changed.

Example 2 (Comparative Example) Surge voltage absorbing element 8
0, 81 were not provided (surge voltage absorbing elements 80, 8
1 was opened), a high-frequency glass antenna for automobiles having exactly the same specifications as in Example 1 was manufactured. The frequency-sensitivity characteristics of the AM broadcast band and the FM broadcast band were almost the same as in Example 1.

After repeating the tests (1) to (4) in Example 1 for 500 times each, the resistance values of the resistors 47 and 48 were measured to determine whether or not the resistors 47 and 48 had deteriorated. Then, the resistance value changed to infinity.

[0066]

According to the present invention, the first resonance including the impedance of the antenna conductor and the inductance of the first coil is generated as a resonance element, and the impedance of the defogger and the inductance of the second coil are included as resonance elements. Since the second resonance is generated and the two resonances are used, the sensitivity in the low frequency band is excellent.

Further, a filter circuit for cutting off or attenuating a reception signal in a high frequency band is electrically connected between the antenna conductor and the defogger. Since the filter circuit includes a high frequency choke coil, the filter circuit includes a high frequency choke coil. Excitation signals in the high frequency band that are excited rarely leak to the vehicle body ground or the like, and the sensitivity in the high frequency band is unlikely to decrease.

Also, when receiving in the low frequency band, both the antenna conductor and the defogger can be used, so that the sensitivity in the low frequency band is excellent, and when receiving in the high frequency band, the effective length of only the antenna conductor is used. Because of this, the sensitivity in the high frequency band is excellent.

Further, even if a surge voltage is applied to the antenna conductor 3 and / or the defogger 90, the charge of the surge voltage flows to the vehicle body ground via the surge voltage absorbing element and does not reach the resonance circuit 6, so that the resonance circuit 6 6 is not easily damaged.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of another embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram for explaining the operation of the antenna conductor 3, the defogger 90 and the resonance circuit 6 in the device of FIG.

FIG. 4 is a configuration diagram of a conventional antenna device.

FIG. 5 is a frequency-sensitivity characteristic diagram of a medium-wave broadcast band of Example 1;

FIG. 6 is a frequency-sensitivity characteristic diagram of an FM broadcast band of Example 1;

[Explanation of symbols]

 1: vehicle rear window glass plate 2: heater wire 3a: antenna conductor 3b: defogger 4a, 4b: feed point 5a, 5b: bus bar 6: resonance circuit 7: receiver 10: DC power supply 31: first coil 32: 2nd coil 33: stray capacitance of antenna conductor 3 34: stray capacitance of defogger 90 41, 44: DC cut capacitor 42: bypass capacitor 43: coupling capacitor 45, 46: damping resistor 47: resistor 52: high frequency choke Coils 80 and 81 are surge voltage absorbing elements 90: defogger E1: voltage power supply for antenna conductor 3 E2: voltage power supply for defogger 90

Claims (1)

[Claims] An electric heating type defogger having a heater wire and a bus bar, and an antenna conductor are provided on a rear window glass plate of the vehicle, and are provided between the bus bar and a DC power supply and / or between the bus bar and the vehicle body. A vehicle glass antenna device in which a choke coil is connected to a ground, comprising a first coil and a second coil, wherein the impedance of the antenna conductor and the inductance of the first coil are included as resonance elements. A first resonance is generated, a second resonance including the defogger impedance and the inductance of the second coil as resonance elements is generated, and a reception signal in a first reception frequency band and a first reception A reception signal in a second reception frequency band higher than the frequency band is transmitted to the receiver from the antenna conductor, and the resonance frequency of the first resonance and the second resonance frequency are transmitted to the receiver. Are the frequencies at which the sensitivity in the first reception frequency band is improved, and a filter circuit for blocking or attenuating the reception signal in the second reception frequency band is electrically connected between the antenna conductor and the defogger. The filter circuit includes a high-frequency choke coil, the first coil is electrically connected between the antenna conductor and the receiver via a wiring and / or a circuit element, and the defogger and the vehicle body ground are connected. And the second coil is wired and / or
Alternatively, a surge voltage absorbing element is electrically connected via a wiring and / or a circuit element between the line between the first coil and the antenna conductor and the vehicle body ground. A glass antenna device for a vehicle, wherein a surge voltage absorbing element is electrically connected between a defogger and a vehicle body ground via wiring and / or a circuit element.