JP3700372B2 - Glass antenna device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention includes a long wave broadcasting band (LW band) (150 to 280 kHz), a medium wave broadcasting band (530 to 1630 kHz), a short wave broadcasting band (SW band) (2.3 to 26.1 MHz), an FM broadcasting band (76 to 90MHz (Japan)), FM broadcast band (88-108MHz (US)), TV VHF band (90-108MHz, 170-222MHz), TV UHF band (470-770MHz), etc., high reception sensitivity, low The present invention relates to a glass antenna device for a vehicle that is noise and has high productivity.
[0002]
[Prior art]
  Conventionally, the glass antenna device for a vehicle of FIG. 7 has been proposed as a glass antenna device for a vehicle that improves the reception sensitivity by using resonance (Actual 4-53070). In this conventional example, a defogger 90 composed of a heater wire 2 and bus bars 15a, 15b, 15c is provided on the rear window glass plate 1 of the vehicle, and the choke coil 9 is connected between the bus bars 15a, 15b and the DC power source 10 for the defogger 90. By connecting and increasing the impedance of the choke coil 9 in the high frequency band, a direct current flows from the DC power source 10 to the defogger 90, but a current in a high frequency band such as a broadcasting frequency band is cut off, and the defogger 90 is connected to the antenna. It is used as.
[0003]
  Further, in the medium wave broadcast band, the grounded floating capacitance (hereinafter simply referred to as the floating capacitance) of the defogger 90 and the coil 71 are caused to resonate in parallel. To pass. Reference numeral 11 denotes a noise-cutting capacitor.
  In the conventional example of FIG. 7, such a configuration is adopted to improve reception sensitivity and reduce noise.
[0004]
  However, in this conventional example, the stray capacitance of the cable connecting the defogger 90 and the receiver is an element that causes parallel resonance, and a parallel resonance frequency exists in the medium wave broadcast band. Since the S / N ratio was poor and there was only one resonance, the reception sensitivity was not sufficient.
[0005]
  Further, when the defogger 90 is used as an antenna for both the medium wave broadcast band and the FM broadcast band, even when the shape of the defogger 90 is optimal for receiving the medium wave broadcast, when receiving the medium wave broadcast, FM broadcast reception is possible. There was a problem that sensitivity and directivity were insufficient.
[0006]
[Problems to be solved by the invention]
  The present invention aims to eliminate the above-mentioned drawbacks of the prior art, and provides a glass antenna device for a vehicle having high receiving sensitivity, low noise, and good productivity.
[0007]
[Means for Solving the Problems]
  The present inventionAn electric heating type defogger having a heater wire and a bus bar for supplying power to the heater wire, and an antenna conductor are provided on the rear window glass plate of the vehicle, between the bus bar and the DC power source, and between the bus bar and the vehicle body ground. In the vehicle glass antenna device in which the choke coil is connected to at least one of the
  A first coil and a second coil;
  Causing a first resonance including the impedance of the antenna conductor and the inductance of the first coil as a resonance element;The first resonance is a series resonance;
  The inductance of the parallel connection circuit of the second coil and the choke coil and the impedance of the defogger are the main resonance elements of the second resonance, and the second resonance is the parallel resonance.
  The reception signal in the first reception frequency band and the reception signal in the second reception frequency band higher than the first reception frequency band are sent from the antenna conductor to the receiver,
  A first coil is electrically connected between the antenna conductor and the receiver, and a second coil is electrically connected between the defogger and the vehicle body ground;
  The maximum frequency of the first reception frequency band is f _H F _H A resonance frequency of the first resonance exists between a frequency 1.5 times the first resonance frequency and a substantially center frequency of the first reception frequency band, and the lowest frequency of the first reception frequency band is f _L F _L A resonance frequency of the second resonance exists between a frequency 0.6 times of the first resonance frequency and a substantially center frequency of the first reception frequency band,
  A filter circuit for blocking or attenuating a reception signal in the second reception frequency band between the antenna conductor and the defogger;Provided is a glass antenna device for a vehicle which is electrically connected.
0008]
0009]
0010]
0011]
[0012]]
[0013]
DETAILED DESCRIPTION OF THE INVENTION
  FIG. 1 is a basic configuration diagram of a vehicle glass antenna device of the present invention using a rear window glass plate 1 of an automobile. In FIG. 1, 2 is a heater wire, 3aIsAntenna conductor, 4a isFeed points, 5a and 5b are bus bars, 6 is a resonance circuit, 7 is a receiver, 31 is a first coil, 32 is a second coil, and 90 is a defogger., 91 is a feeding point provided at the tip of the lead wire connected to the defogger 90It is.
[0014]
  Antenna conductor 3a andDefogga 90The distance between the two is generally about 0.1 to 50 mm. Capacitively coupledTheAntenna conductor 3a andDefog 90The direct current is not transmitted / received between them, but the high frequency current of the received signal is transmitted / received.
0015]
0016]
[0017]
  Antenna conductor 3aAnd defogger 90 may be placed close to each other and capacitively coupledNo.
[0018]
  HWithout providing the yoke coil 9, the defogger 90 and the DC power source 10 are directly connected.TheIn this case, the defogger 90 is not cut off from the vehicle ground in the broadcast frequency band, and if the capacity coupled capacity is too large,TAntenna conductor 3aThe induced reception signal leaks to the vehicle body ground through the defogger 90, and the reception sensitivity decreases.
[0019]
  If the capacity coupled capacity is too large, the engine noise present in the defogger 90IsAntenna conductor 3aThe flow and S / N ratio also deteriorate. When the choke coil 9 is not providedAAntenna conductor 3a andThe coupling capacity with the defogger 90 is usually preferably 100 pF or less. In the case of 100 pF or less, the receiving sensitivity is usually improved by 0.5 dB or more compared to the case of over 100 pF.
[0020]
  Similarly, from the viewpoint of the S / N ratio,AlwaysAntenna conductor 3a andThe coupling capacitance with the defogger 90 is preferably 50 pF or less. In the case of 50 pF or less, the S / N ratio is usually improved by 2.0 dB or more compared to the case of over 50 pF. A more preferable range is 25 pF or less. In the case of 25 pF or less, the S / N ratio is usually improved by 3.0 dB or more compared to the case of over 25 pF.
[0021]
  As shown in FIG. 1, you may short-circuit the part other than the bus bar of the several heater wire 2 provided in the glass plate 1 of a rear window with a short circuit wire. A short-circuit line 21 that short-circuits the heater wire 2 at a portion other than the bus bar is provided as necessary, and has a function of stabilizing the impedance of the defogger 90 when the defogger 90 is used as an antenna. Moreover, the short-circuit line 21 also has a high bandwidth function.
[0022]
  FIG. 2 shows the device of FIG.TThe antenna conductor 3a andDefog 90FIG. In FIG. 2, E1Is aThe voltage power supply for the antenna conductor 3a, E2 isDefog 90Voltage power supply, 33Is aThe stray capacitance of the antenna conductor 3a, 34 isDefog 90Stray capacitance of 35Is aThe antenna conductor 3a andDefog 90The proximity capacity.
[0023]
  Defog 90Is mainly intended for reception in the first reception frequency band (hereinafter referred to as the low frequency band), and the conductor length and conductor shape should be set so as to obtain suitable reception performance in the low frequency band Is preferred. AThe antenna conductor 3a is preferably used for reception in a second reception frequency band (hereinafter referred to as a high frequency band) having a frequency higher than that in the low frequency band so that suitable reception performance can be obtained in the high frequency band. It is preferable to set the conductor length and the conductor shape.
[0024]
  For example, when the high frequency band is FM broadcast band, TV VHF band or TV UHF bandAThe width of each element constituting the antenna conductor 3a is such that the glass shortening rate is K and the wavelength of the highest frequency in the high frequency band is λ._H , The wavelength of the lowest frequency in the high frequency band λ_L (Λ_H / 4) × K to λ_L A range of × K is preferred. The glass shortening rate K is 0.64.
[0025]
  When the low frequency band is the medium wave broadcasting band,Defog 90It is preferable to use as long a conductor length as possible to maximize the usable area..
[0026]
  AAntenna conductor 3a,Defog 90Can be used for medium wave broadcast band, FM broadcast band, short wave broadcast band, long wave broadcast band, TV VHF band, TV UHF band, telephone reception and the like. For example, generally, 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.
[0027]
  In the present invention, two resonances are caused to improve reception sensitivity. For the first resonanceAThe impedance of the antenna conductor and the inductance of the first coil are included as resonance elements.
[0028]
  AThe impedance of the antenna conductor 3a is mainly composed of stray capacitance 33.AIs the impedance of the antenna conductor 3a the feed point 4a?RThe impedance when the antenna conductor 3a side is seen. Further, the resonance frequency of the first resonance may be adjusted by connecting a capacitance component in parallel between the stray capacitance 33 and the vehicle body ground. This capacitive component can also be a resonance element of the first resonance.
[0029]
  The first resonance is also affected by the stray capacitance of the wiring around the first coil 31, the stray capacitance of the cable connected between the glass antenna and the receiver, and the proximity capacitance 35, which are also the first resonance. Can be a resonance element of the resonance.
[0030]
  In addition, a new circuit element is provided inside the resonance circuit 6.TImpedance matching between the antenna conductor 3a and the receiver side may be performed. The first coil 31 is usually about 10 μH to 1 mH.
[0031]
  For the second resonance,Defog 90And the inductance of the second coil are included as resonance elements.Defog 90Impedance mainly consists of stray capacitance 34,Defog 90Is the impedance from the feed point 4bDefog 90The impedance when looking at the side. Further, the resonance frequency of the second resonance may be adjusted by connecting a capacitance component in parallel between the stray capacitance 34 and the vehicle body ground. This capacitive component can also be a resonance element of the second resonance.
[0032]
  The second coil 32 is usually about 10 μH to 1 mH. Further, in the second resonance, the stray capacitance and the proximity capacitance 35 of the wiring around the second coil 32 can also be the resonance elements of the second resonance. The stray capacitance of the cable connected between the resonance circuit 6 and the receiver also affects the second resonance.
[0033]
  Note that when the second coil 32 loses inductance in a high frequency band such as the FM broadcast frequency among the broadcast frequencies (that is, has a capacitive property), the received signal leaks to the vehicle body ground and is received. Sensitivity falls. In order to prevent this, a high frequency choke coil (not shown) may be connected to the second coil 32 in series. Usually, about 0.1 to 100 μH is used for this high-frequency choke coil.
[0034]
  Antenna conductor 3a andDefog 90And are capacitively coupled,Defog 90The received signal is transmitted to the receiver side via the proximity capacitor 35. A new circuit element is provided inside the resonance circuit 6Defog 90And impedance matching may be performed on the receiver side. In FIG. 1, the first resonance is a series resonance and the second resonance is a parallel resonance..
[0035]
  In the present invention, two resonances are generated because one resonance alone cannot cover a wide reception frequency band. Therefore, in the present invention, it is desirable to divide the low frequency band into two at substantially the center frequency, and share each of them by two resonances to flatten the reception sensitivity. Here, the flattening of the reception sensitivity means to reduce the difference between the maximum reception sensitivity and the minimum reception sensitivity in a band such as a low frequency band.
[0036]
  The resonance frequency of the first resonance and the resonance frequency of the second resonance are frequencies that improve the sensitivity in the low frequency band. However, the maximum frequency of the low frequency band is f_H F_H The resonance frequency of the first resonance is present between a frequency 1.5 times higher than the center frequency of the low frequency band and the lowest frequency of the low frequency band is f_L F_L The resonance frequency of the second resonance is present between a frequency 0.6 times as high as approximately the center frequency of the low frequency band. This is because it is preferable in terms of flattening the reception sensitivity. If it is out of this range, it becomes difficult for the difference between the highest reception sensitivity and the lowest reception sensitivity in the low frequency band to be generally about 10 dB or less, and the flattening of the reception sensitivity is inferior in the low frequency band.
[0037]
  Further, the resonance frequency of the first resonance is preferably in the low frequency band from the viewpoint of improving reception sensitivity. When it exists in the low frequency band, the reception sensitivity of the entire low frequency band is generally improved by about 10 dB compared to the case where it does not exist.
[0038]
  Therefore, in order to improve both flatness and reception sensitivity, f_H And the resonance frequency of the first resonance between the center frequency of the low-frequency band and f_L A resonance frequency of the second resonance exists between a frequency 0.6 times the frequency and a substantially center frequency in the low frequency band.PreferGood.
[0039]
  When the first resonance is series resonance, the resonance frequency of the first resonance is preferably higher than the substantially center frequency in the low frequency band. When the second resonance is parallel resonance, the resonance frequency of the second resonance is preferably lower than the substantially center frequency in the low frequency band. When the second resonance is a parallel resonance, the reception sensitivity is significantly lowered in a range lower than the resonance frequency of the parallel resonance.
[0040]
  FIG. 3 is a circuit diagram of a modified example of the resonance circuit 6. In FIG. 3, 41, 44, 50 and 51 are DC cut capacitors, 42 is a bypass capacitor, 43 is a coupling capacitor, 45, 46, 48 and 49 are damping resistors, and 47 is a vehicle such as engine noise. This is a resistor for reducing noise.
[0041]
  In the resonant circuit of FIG.Defog 90The received signal is transmitted to the receiver side through the capacitor 51, the resistor 47, and the capacitor 43. However,AThe antenna conductor 3a andDefog 90And are capacitively coupled,Defog 90The received signal is also transmitted to the receiver side via the proximity capacitor 35.
[0042]
  The bypass capacitor 42 is provided as necessary, and has a function of passing the high frequency band and sending it to the receiver side. For example, when the low frequency band is a medium wave broadcast band, the FM broadcast band is passed by the bypass capacitor 42 when FM broadcast reception is also performed.
[0043]
  Capacitor 43Is aThe antenna conductor 3a andDefog 90For strengthening the capacitive coupling with and provided as necessary. AThe antenna conductor 3a andDefog 90The connection to is made by the capacitor 43 in the case of FIG. However, other components such as resistors may be connected. Further, resistors 45, 46, 48, and 49 are provided as necessary to adjust the flattening of reception sensitivity. In addition, a resonance adjusting capacitor or the like may be provided.
[0044]
  Capacitors 41, 44, 50, and 51 are provided as necessary, and normally 100 pF to 50 μF are used. Usually, 1 to 1000 pF is used for the bypass capacitor 42. Usually, 5 to 500 pF is used for the capacitor 43. The resistors 45, 46, and 49 are usually 50Ω to 100kΩ.
[0045]
  The stray capacitance of the cable connecting the resonance circuit 6 and the receiver 7 affects the second resonance and causes the S / N ratio to deteriorate due to vehicle noise such as engine noise. The resistor 47 is provided as necessary, and has a function of preventing this S / N ratio deterioration. In particular, it has a function of preventing deterioration of the low-frequency S / N ratio in the medium wave broadcasting band. That is, the resistor 47 has a function of reducing vehicle noise such as engine noise.
[0046]
  The resistance value of the resistor 47 is preferably 10Ω to 1 kΩ, more preferably 50 to 500Ω. When the low frequency band is a medium wave broadcast band, when the resistance value of the resistor 47 is 10 Ω to 1 kΩ, the S / N ratio of the medium wave broadcast band is compared to the case outside the range of 10 Ω to 1 kΩ. Is improved by 1 dB or more. When the resistance value of the resistor 47 is 50 to 500Ω, the S / N ratio of the medium wave broadcasting band is improved by 1 dB or more compared to the case outside the range of 50 to 500Ω.
[0047]
  As described above, in FIG. 3, capacitors 41, 42, 43, 44, 50, 51, resistors 45, 46, 47, 48, and 49 are provided as necessary, and can be omitted. The omission of the resistors 45, 46, 49 is to open, the omission of the capacitors 41, 43, 44, 50, 51, and the omission of the resistors 47, 48 are to short circuit.
[0048]
  FIG. 6 shows a circuit diagram of a resonance circuit of a different type from FIG. In FIG. 6, 52 is a high frequency choke coil. The high frequency choke coil 52 is provided as necessary. The omission of the high-frequency choke coil 52 is a short circuit.
[0049]
  The high frequency choke coil 52 isAThe antenna conductor 3a andDefog 90Are separated in high frequency in the normal high frequency band.AThe antenna conductor 3a has a function of improving reception sensitivity in a high frequency band without changing the effective length of the conductor. The high-frequency choke coil 52 is usually about 0.1 to 1000 μH.
[0050]
  When the second coil 32 has a low self-resonance frequency in the high frequency band and loses inductance,AThe reception signal in the high frequency band excited by the antenna conductor 3a leaks to the vehicle body ground via the second coil 32, and the reception sensitivity is lowered, so that the inductance is not lost in the high frequency band (that is, the capacitive property and The high frequency choke coil 52 can prevent the received signal in the high frequency band from leaking to the vehicle body ground via the second coil 32.
[0051]
  In other words, the high-frequency choke coil 52 has a filter function that allows the low-frequency band to pass and blocks or attenuates the high-frequency band. When the high frequency choke coil 52 is provided, the high frequency band reception sensitivity is usually improved by 1 dB or more as compared with the case where the high frequency choke coil 52 is not provided.
[0052]
  In FIG.AIn order to prevent the received signal in the high frequency band excited by the antenna conductor 3a from leaking to the vehicle body ground.AThe antenna conductor 3a andDefog 90A high frequency choke coil 52 is connected between the two. However, it is not limited to thisAThe antenna conductor 3a andDefog 90Any filter circuit that cuts off or attenuates the received signal in the high frequency band may be used.
[0053]]
[0054]]
0055]
[0056]
  ReceivingIn order to improve the sensitivity,AAntenna conductor 3aIt may be close and capacitively coupled. When fully capacitively coupled,1As shown, it is preferable to connect the choke coil 9 between the defogger 90 and the DC power supply 10 for the defogger 90 to insulate the defogger 90 from the vehicle body ground. When capacitive coupling is performed in this manner, the reception sensitivity is improved by several dB or more compared to the case where capacitive coupling is not performed. The distance between the two for capacitive coupling is usually about 0.1 to 50 mm. The choke coil 9 is usually about 0.1 to 10 mH.
[0057]
  Figure1, The choke coil 9 and the high-frequency choke coils 12a and 12b are inserted between the bus bars 5a and 5b and the DC power supply 10 for the defogger 90, and the impedance of the choke coil 9 and the high-frequency choke coils 12a and 12b in the broadcast frequency band. Is increased, a direct current from the direct current power source 10 to the defogger 90 flows, but a current in the broadcast frequency band is cut off.
[0058]
  In this manner, the choke coil 9 and the high-frequency choke coils 12a and 12b can insulate the heater wire 2 and the bus bars 5a and 5b of the defogger 90 from the ground of the vehicle body in a high frequency, and receive current in the broadcast frequency band induced in the defogger 90 Can be prevented from flowing to the vehicle body ground, and this received current can be sent to the receiver without leakage.
[0059]
  The high-frequency choke coils 12a and 12b have high impedance in a high frequency band such as the FM broadcast frequency band in the broadcast frequency band, and normally use a solenoid or a magnetic core. These have inductive inductance in a high frequency band such as the FM broadcast frequency band and in the vicinity of the frequency band. Since the choke coil 9 has a low self-resonance frequency in a high frequency band such as the FM broadcast frequency band and may lose its inductance, the high-frequency choke coils 12a and 12b act as a substitute. As for the high frequency choke coils 12a and 12b, about 0.1 to 100 μH is usually used.
[0060]
  When the choke coil 9 loses inductance in a high frequency band such as the FM broadcast frequency band, the high frequency choke coils 12a and 12b are not necessary. In short, if only a low frequency band such as an AM broadcast frequency band is received, the high frequency choke coils 12a and 12b are usually unnecessary, and only the choke coil 9 may be used, and a high frequency band such as an FM broadcast frequency band is sufficient. If only the high-frequency choke coils 12a and 12b are received, only the high-frequency choke coils 12a and 12b are required. Even in the case of receiving both the low frequency band and the high frequency band, if there is a coil that satisfies the functions of both the choke coil 9 and the high frequency choke coils 12a and 12b, such a coil is sufficient.
0061]
[0062]]
[0063]
  FigureIn 1If the capacitor 51 is not provided and the location of the capacitor 51 is short-circuited, the direct current flowing through the defogger 90 flows into the second coil 32, so that the current capacity of the second coil 32 must be increased. In other words, the productivity is deteriorated, and further, since the direct current flowing through the defogger 90 flows into the vehicle body ground via the coil 32, the current is wasted. Therefore, it is preferable to provide the capacitor 51.
[0064]
  Figure1The capacitor 51 is connected between the feeding point 91 and the second coil 32, and since the feeding point 91 is connected to the bus bar 5b, it is connected between the bus bar 5b and the second coil 32. ing. However, the present invention is not limited to this, and the capacitor 51 may be connected between the bus bar 5 a and the second coil 32, or may be connected between the heater wire 2 and the second coil 32. . In other words, the location of the defogger 90 to which the second coil 32 is connected is not limited.
[0065]]
[0066]
  As mentioned aboveThe resonance frequency of the first resonance may be adjusted by connecting a capacitance component in parallel between the stray capacitance 33 and the vehicle body ground. This capacitive component can also be a resonance element of the first resonance.
  AlsoASince the antenna conductor 3a and the defogger 90 are electrically connected, the impedance of the defogger 90 also affects the first resonance and can be a resonance element of the first resonance.
[0067]
  The impedance of the defogger 90 is mainly composed of the stray capacitance 34, and the impedance of the defogger 90 is an impedance when the defogger 90 side is viewed from the feeding point 91. Furthermore, the first resonance is also affected by the stray capacitance of the wiring around the first coil 31, the stray capacitance of the cable connected between the glass antenna and the receiver, and the proximity capacitance 35. Can be a resonance element. The first resonance is the figure1It is a series resonance.
[0068]
  A new circuit element is provided inside the resonance circuit 6.TImpedance matching between the antenna conductor 3a and the receiver side may be performed. The first coil 31 is usually about 10 μH to 1 mH.
[0069]
  Regarding the second resonance, at least one of the inductance of the second coil 32 and the inductance of the choke coil 9 and the impedance of the defogger 90 are included as resonance elements.
[0070]
  AlsoASince the antenna conductor 3a and the defogger 90 are electrically connected, the second resonanceIs aThe impedance of the antenna conductor 3a is also affected and can be a resonant element of the second resonance.
Furthermore, the second resonanceAThe stray capacitance of the wiring around the antenna conductor 3a, the stray capacitance of the wiring around the defogger 90, the stray capacitance of the wiring around the second coil 32, and the proximity capacitance 35 also affect and can be a resonance element of the second resonance. The stray capacitance of the cable connected between the output of the resonance circuit 6 and the receiver also affects the second resonance. Also figure1The second resonance in this is a parallel resonance.
[0071]]
[0072]]
[0073]
  Figure1The resonance frequency of the first resonance and the resonance frequency of the second resonance are frequencies that improve the sensitivity in the low frequency band. When the low frequency band is a medium wave broadcasting band, the resonance frequency of the parallel resonance is preferably 350 to 530 kHz, and more preferably 450 to 500 kHz, from the viewpoint of improving the S / N ratio.
[0074]
  Further, the resonance frequency of the second resonance may be adjusted by connecting a capacitance component in parallel between the stray capacitance 34 and the vehicle body ground. This capacitive component can also be a resonance element of the second resonance. The second coil 32 is usually about 10 μH to 1 mH.
[0075]
  Figure1The high frequency choke coil 52, which is an inductance element, is provided as necessary.AThe antenna conductor 3a and the defogger 90 are separated in a high frequency band in a normal high frequency band.AThe antenna conductor 3a has a function of improving reception sensitivity in a high frequency band without changing the effective length of the conductor.
[0076]
  In the case where the high-frequency choke coil 52 is not provided and the choke coil 9 or the second coil 32 has a low self-resonance frequency in the high frequency band and has a strong capacitive property.AA reception signal in a high frequency band excited on the antenna conductor 3a leaks from the ground of the vehicle body. Therefore, a high frequency choke coil 52 is provided to prevent this. Figure1The high-frequency choke coil 52 is normally about 0.1 to 1000 μH. By providing the high-frequency choke coil 52, the inductance value of the high-frequency choke coil 52 is increased so that the sensitivity in the high frequency band is improved by 0.3 dB or more. It is preferable to set.
[0077]
  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, the high frequency choke coil 52 has 0.5 to 10 μH. Usually used. The high-frequency choke coil 52 has a sensitivity of 2 dB or more when it is within the range of 0.5 to 10 μH, compared with the case outside the range of 0.5 to 10 μH.
[0078]
  Figure1LeaveAIn order to prevent the reception signal in the high frequency band excited by the antenna conductor 3a from leaking from the vehicle body ground.AA high-frequency choke coil 52 was connected between the antenna conductor 3a and the defogger 90. However, it is not limited to thisAWhat is connected between the antenna conductor 3a and the defogger 90 may be any filter circuit that blocks or attenuates a received signal in a high frequency band.
[0079]
  Also figure1LeaveAThe antenna conductor 3a and the defogger 90 are preferably not capacitively coupled. For capacitive couplingAThe reception signal in the high frequency band excited on the antenna conductor 3 a is likely to leak to the vehicle body ground via the defogger 90 and the choke coil 9.
[0080]
  Figure4The figure1'sA glass antenna device for vehicles is developed to receive diversity. Figure4, 53 is a capacitor, t₁ Is the first input of the receiver 7, t₂ Is the second input of the receiver 7. In the receiver 7, the first input t₁ And the second input t₂ The stronger one of the received signals in the high frequency band is selected.
[0081]
  The capacitor 53 is provided as necessary, and has a function of blocking or attenuating a received signal in a low frequency band. The capacitance value of the capacitor 53 is preferably 10 to 150 pF, and more preferably 20 to 70 pF. When the low frequency band is a medium wave broadcast band, when the capacitance value of the capacitor 53 is set to 10 to 150 pF, the sensitivity of the medium wave broadcast band is improved by 1 dB or more as compared with the case outside the range of 10 to 150 pF. To do. When the capacitance value of the capacitor 53 is set to 20 to 70 pF, the sensitivity of the medium wave broadcast band is improved by 1 dB or more as compared with a case where the capacitance value is outside the range of 20 to 70 pF.
[0082]
  Figure4In the vehicle glass antenna deviceHighThe frequency choke coils 12a and 12b are preferably connected between the bus bar and the choke coil 9. Figure1'sThe received signal in the high frequency band excited by the defogger 90 and not used in the apparatus is input to the second input t.₂ In order to prevent the leakage of the received signal in the high frequency band excited by the defogger 90 by the high frequency choke coils 12a and 12b to the vehicle body ground. Figure4The resonant circuit 6 ofFIG.The present invention can also be applied to glass antenna devices for vehicles.
[0083]]
[0084]
  FIG.4The defogger 90 shown in FIG. 7 has a so-called substantially C-shape, but the defogger 90 according to the present invention is not limited to this, and even a so-called substantially U-shaped defogger 90 as shown in FIG. Can be used for invention.
  AAntenna conductor 3a andDefog 90May be provided anywhere above, below, left, or right margins 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.
[0085]
  In the present inventionAAntenna conductor 3a andDefog 90Besides, the number of antenna conductors provided in the vehicle is not limited. Moreover, you may perform diversity reception between other antenna apparatuses, such as the glass antenna apparatus of this invention, a pole antenna, or another glass antenna apparatus.
[0086]
  Although the feeding points 4a and 4b are arranged at the right peripheral edge of the window glass plate 1 in FIG. 1, the present invention is not limited to this, and may be arranged at any position on the window glass plate 1, for example, a window The glass plate 1 may be disposed at the upper and lower peripheral edges at the center of the left and right.
[0087]
  Shown in Figure 1SuaAntenna conductor 3a andDefog 90There is no auxiliary antenna conductor attached. However, for the purpose of phase adjustment and directivity adjustment, auxiliary antenna conductors such as a substantially T shape and a substantially L shape may be attached to the conductor patterns or feeding points of these antenna conductors.
[0088]
  In the present invention,AAntenna conductor 3a andDefog 90The window glass plate provided with is not limited to the rear window glass plate, and may be a side window glass plate, a front window glass plate, a roof window glass plate, etc., and the defogger 90 is provided on the window glass plate provided with the antenna conductor. It may not be provided.
[0089]
【Example】
0090]
0091]
[0092]]
[0093]]
[0094]]
[0095]]
[0096]
"Example1(Comparative example) "
  A conventional glass antenna device for a vehicle as shown in FIG. 7 was manufactured. The coil 71 was 680 μH, the coil 72 was 100 μH, the capacitor 73 was 30 pF, and the resistor 74 was 5 kΩ. The same thing as Example 1 was used for the window glass board and the defogger 90 provided in a window glass board.
[0097]
  FIG. 5 is an S / N characteristic diagram at 600 kHz. Measurement was performed by radiating radio waves from a transmitting antenna connected to a signal generator in a shield room. In FIG. 5, the horizontal axis represents the output voltage of the signal generator, and the vertical axis represents the output voltage of the low-frequency amplifier circuit at the final stage of the receiver in dB. The output of the signal generator was set to 120 dBμV, and the input was sufficiently input to the receiver to saturate the S / N (saturated state). At this time, a modulation frequency of 400 Hz was adopted for the modulation of the signal generator, and the modulation factor was 30%. The state at this time was defined as 0 (zero) dB on the vertical axis.
[0098]
  In FIG. 5, the solid line is the S / N characteristic of Example 1 and the wavy line is Example 2. At 50 to 120 dBμV, both the solid line and the wavy line branch up and down. The line above the branch is the state when modulated (audio signal (S) + noise (N)), and the line below the branch is in a state where no modulation is applied to the radio wave from the transmitting antenna. Yes (no modulation, noise (N) only).
[0099]
  The greater the difference in dB between the upper line and the lower line in FIG. 5, the greater the S / N ratio and the better the reception. Note that the S / N characteristics in FIG. 5 are irrelevant to vehicle noise such as engine noise and are not affected by the operation or stop of the engine.
0100]
[0101]]
[0102]]
[0103]]
[0104]]
[0105]]
[0106]
"Example2 (Example)"
  Use car rear window glass plate, figure1A glass antenna device as shown was manufactured. Each circuit constant is as follows.
  First coil 31 = 150 μH,
  Second coil 32 = 560 μH,
  High-frequency choke coil 52 = 2.2 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,
  The stray capacitance of the defogger 90 = 100 pF.
[0107]
  AThe antenna conductor 3a is adjusted in conductor length and conductor shape so that it can receive the medium wave broadcast band and the FM broadcast band.. AThe distance between the lower part of the antenna conductor 3a and the uppermost line of the heater wire 2 was increased to 15 mm. in this caseAThe antenna conductor 3a and the defogger 90 were slightly capacitively coupled.
[0108]
  Figure8Is a characteristic diagram of the sensitivity of the medium wave broadcasting band. Figure8Then, the sensitivity of a pole antenna having a length of 910 mm is compared, and the sensitivity of the pole antenna is 0 dB. The resonance frequency of the first resonance (series resonance) was 1450 kHz, and the resonance frequency of the second resonance (parallel resonance) was 480 kHz. FIG. 9 is a characteristic diagram of the sensitivity of the FM broadcast band.
[0109]
【The invention's effect】
  In the present inventionACausing a first resonance including the impedance of the antenna conductor and the inductance of the first coil as a resonance element;DefogahThe second resonance including the impedance of the second coil as a resonance element is generated, and the two resonances are used, so that the sensitivity is excellent. Furthermore, since the stray capacitance of the cable connected between the glass antenna and the receiver has little influence on the second resonance, the S / N ratio is dramatically improved.
[0110]
  In the present invention, even when two different frequency bands, a low frequency band and a high frequency band, are received.AThe antenna conductor is designed to be suitable for high frequency band reception,DefogahIs designed to be suitable for low frequency band reception, so that both frequency bands can be received well. Furthermore, since the adjustment for receiving both frequency bands can be performed separately, the adjustment becomes easy, which can contribute to the improvement of productivity.
[0111]]
[0112]
  LowWhen receiving the frequency bandASince both the antenna conductor and the defogger can be used, it has excellent sensitivity in the low frequency band.ASince the effective length of only the antenna conductor can be used, the sensitivity in the high frequency band is excellent..
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of a glass antenna device for a vehicle according to the present invention.
FIG. 2 shows the smell of the apparatus of FIG.TThe antenna conductor 3a andDefog 90Equivalent circuit diagram
FIG. 3 is a circuit diagram of a modified example of the resonance circuit 6;
FIG. 4Configuration of a glass antenna device for a vehicle according to the present invention of a type different from the above
FIG. 5 is an S / N characteristic diagram of Example 1 and a conventional example.
6 is a circuit diagram of a resonance circuit 6 of a type different from that shown in FIG.
[Fig. 7]Prior artConfiguration diagram of antenna device
[Fig. 8]Example 6 Sensitivity characteristics of medium wave broadcasting band
FIG. 9Sensitivity characteristics chart of FM broadcast band in Example 6
[Explanation of symbols]
1: Rear window glass plate of vehicle
2: Heater wire
3a:AAntennabody
4a:Feeding point
5a, 5b: Bus bar
6: Resonant circuit
7: Receiver
10: DC power supply
31: First coil
32: Second coil
33: AStray capacitance of antenna conductor 3a
34:Defog 90Stray capacitance
35: Proximity capacity
41, 44: DC cut capacitors
42: Bypass capacitor
43: Coupling capacitor
45, 46: Damping resistance
47: Resistance
52: High frequency choke coil
90: Defogga
E1: AVoltage power supply for antenna conductor 3a
E2:Defog 90Voltage power supply

Claims (6)

An electric heating type defogger having a heater wire and a bus bar for supplying power to the heater wire, and an antenna conductor are provided on the rear window glass plate of the vehicle, between the bus bar and the DC power source, and between the bus bar and the vehicle body ground. In the vehicle glass antenna device in which the choke coil is connected to at least one of the
A first coil and a second coil;
A first resonance including the impedance of the antenna conductor and the inductance of the first coil as a resonance element is generated, and the first resonance is a series resonance;
The inductance of the parallel connection circuit of the second coil and the choke coil and the impedance of the defogger are the main resonance elements of the second resonance, and the second resonance is the parallel resonance.
The reception signal in the first reception frequency band and the reception signal in the second reception frequency band higher than the first reception frequency band are sent from the antenna conductor to the receiver,
A first coil is electrically connected between the antenna conductor and the receiver, and a second coil is electrically connected between the defogger and the vehicle body ground;
The highest frequency of the first reception frequency band is f _H Where f _H The resonance frequency of the first resonance exists between the frequency 1.5 times the first frequency and the substantially center frequency of the first reception frequency band, and the lowest frequency of the first reception frequency band is set to f _L F _L A resonance frequency of the second resonance exists between a frequency 0.6 times of the first resonance frequency and a substantially center frequency of the first reception frequency band,
A glass antenna device for a vehicle, wherein a filter circuit for blocking or attenuating a reception signal in the second reception frequency band is electrically connected between the antenna conductor and the defogger . When the first reception frequency band is a medium wave broadcasting band,
Resonance frequency of the second resonance is a vehicle glass antenna device according to claim 1 Ru 350~530kHz der. The filter circuit includes a resistor, and the resistor is electrically connected between the antenna conductor and the defogger;
The glass antenna device for a vehicle according to claim 1, wherein the resistance value of the resistor is 10Ω to 1 kΩ . The first reception frequency band is a medium wave broadcast band, and the second reception frequency band is one or more selected from an FM broadcast band, a television VHF band, and a television UHF band . Glass antenna device for vehicles. The glass antenna device for a vehicle according to claim 4, wherein the filter circuit includes a high frequency choke coil, and the inductance value of the high frequency choke coil is 0.5 to 10 µH . The inductance value of the first coil is 10 μH to 1 mH,
The glass antenna device for a vehicle according to claim 1, wherein an inductance value of the second coil is 10 μH to 1 mH .

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