JP3508208B2 - Glass antenna for receiving automobile longwave - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-noise glass antenna for receiving long-wave automobiles, which has excellent receiving sensitivity.

[0002]

2. Description of the Related Art Conventionally, in a glass antenna, in order to compensate for the lack of receiving sensitivity of the antenna, it is possible to insert a preamplifier at a suitable portion of a feed line between a feed terminal of an antenna conductor and a receiver. It was done. However, before inserting the preamplifier Then, strong in an electric field, such as waveform distortion and suppressing intermodulation occurs, noise was a problem that will be amplified as it is.

[0003] Therefore from that of the prior art radio receiver in the case of it is necessary to install a preamplifier separately installed preamplifier considerably and problems productivity may turn poor, in the vicinity of the glass antenna In order to do so, there is a problem that a constraint condition occurs in designing an automobile such as securing a space for a preamplifier. Therefore, without the need for such a preamplifier,
Moreover, it has been desired to develop a glass antenna for an automobile , which has high gain, low noise, and is omnidirectional.

To solve this, Japanese Patent Laid-Open No. 23970/1990
According to Japanese Unexamined Patent Publication (Kokai) No. 1, a defogger of an electrically heated type having a heater wire and a bus bar for feeding the heater wire to a glass plate of a rear window of an automobile, and a direct current is not transmitted and received between the defogger but a high frequency current As for transmission and reception, an antenna conductor with a predetermined pattern that is closely coupled at a predetermined interval and capacitively coupled is provided, and a choke coil is inserted and connected between one bus bar and the battery and between another bus bar and the ground. Then, the matching circuit shown in FIG. 4 is inserted and connected between the feeding point of the antenna conductor and the receiver, and the broadcast frequency is determined by the impedance of the matching circuit, the input impedance of the receiver, and the impedance of the antenna conductor seen from the matching circuit. A glass antenna device that resonates or anti-resonates within a band has been proposed.

[0005] However, the long wave broadcast frequency band (hereinafter referred to as LW band) When you apply this to, not receiving sensitivity to the flat, AM broadcast frequency band (hereinafter referred to as AM band) missing point reception sensitivity that a bad of was there. In addition, when applied to an AM band, there is a missing point reception sensitivity is that a bad of L W-band.

[0006]

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned drawbacks of the prior art, and provides a novel glass antenna for long-wave automobile reception having excellent reception sensitivity in both the AM band and the LW band.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to an electrically heated defogger having a heater wire and a bus bar for supplying power to the heater wire on a glass plate of a rear window of an automobile, and transmitting and receiving a direct current between the defogger. between but is not performed is provided an antenna conductor in proximity with a predetermined interval are capacitively coupled to transmitting and receiving a high-frequency current is performed, the ground and between the other bus bar of the first bus bar and the battery in automotive long wave reception glass antenna inserted connecting choke coils, by the impedance of the choke coil and the defogger, anti-resonance point between half the frequency of the upper limit frequency and the long wave broadcast frequency band lower limit frequency long wave broadcast frequency band , And insert a predetermined circuit between the feeding point of the antenna conductor and the receiver to determine the impedance of the predetermined circuit. By the impedance from the input impedance and a predetermined circuit of the receiver viewed antenna conductor side, long wave broadcast band upper limit frequency and the AM broadcast frequency band
Providing a center frequency of the lower limit frequency, the car long wave reception glass antenna characterized in that as the resonance point exists between 1.5 times the frequency of the AM broadcast frequency band upper limit frequency .

Further, according to the present invention, an electric heating type defogger having a heater wire and a bus bar for feeding the heater wire to a glass plate of a rear window of an automobile, and no direct current is transmitted and received between the defogger. In order to transmit and receive high-frequency current, an antenna conductor that is capacitively coupled in close proximity at a predetermined interval is provided, and choke coils are inserted between one bus bar and the battery and between the other bus bar and the ground. In the connected car longwave receiving glass antenna, the antiresonance point exists in the longwave broadcasting frequency band due to the impedance of the choke coil and the defogger, and a predetermined circuit is provided between the feeding point of the antenna conductor and the receiver. Insert and connect the impedance of the specified circuit, the input impedance of the receiver, and the impedance of the antenna conductor side as viewed from the specified circuit. By the-impedance, provides automotive longwave reception glass antenna characterized in that as there are resonance points in the AM broadcast frequency band.

Further, the present invention provides the above-mentioned glass antenna for automobile long wave reception, characterized in that the resistance of anti-resonance is adjusted by connecting a resistor in parallel with the choke coil.

FIG. 1 shows the configuration of a typical example of a glass antenna for long-wave reception of an automobile 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, 2a is a heater wire uppermost part, 3 is a defogger, 3a is a defogger branch line, 4 is a feeding point of an antenna conductor, 5a, 5b, 5c.
Is a bus bar, 6 is an antenna conductor, 6a is an antenna conductor 6
Adjacent to the defogger 3, 7 is a matching circuit which is a " predetermined circuit " in the present invention , 8 is a reactance circuit, 9 is a heater transformer, 10 is a DC power source, 11 is a capacitor, 12a and 12b are high frequency coils, 13 Is a coil, 15, 16 and 17 are resistors, 12 and 14 are capacitors, 20 is a receiver, and 22a and 22b are leads.

[0011] The glass plate 1 of the rear window, usually 3~5mm
Tempered glass of thickness about or laminated glass or the like is used. In the heated area on the inner surface of the glass plate 1 of the rear window, there are a number of heater wires 2 and electrically conductive heating type heaters having opposing bus bars 5a, 5b, 5c connected to both ends of the group of heater wires 2. The defogger 3 is provided, and the bus bars 5a and 5b of the defogger 3 are connected to the lead wires 22a and 2b.
2b is connected.

In the defogger 3 shown in FIG. 1, one of the bus bars on both sides of the defogger 3, for example, one bus bar is divided into two parts vertically from a desired position, and a lower side bus bar 5a and an upper side bus bar 5b are provided. , Connect the lead wire 22a of the vehicle body side ground to this lower side bus bar 5a,
A current supplied by connecting the power source side lead wire 22b to the upper bus bar 5b flows from the upper bus bar 5b through the bus bar 5c to the lower bus bar 5a in a U-shape.

The defogger shown in FIG. 1 is composed of a large number of thin electric heating heater wires having a line width of 0.5 to 2 mm in the lateral direction of a glass plate, which are arranged substantially parallel to each other at intervals of 2 to 4 cm and are made of conductive silver paste or the like. It is manufactured by printing the conductive metal-containing paste of (1) on the inside surface of a glass plate and baking it.

[0014] adjacent portion 6a of the antenna conductor 6, which is part and <br/> both adjacent portions of the antenna conductor 6 and the defogger 3
And the defogger branch line 3a are capacitively coupled, and direct current is not transmitted and received between them, but they are close to each other at a predetermined interval so that high frequency current is transmitted and received.

[0015] <br/> the branch line 3 a adjacent portion 6a and the defogger are spaced for example at intervals of about 1 to 10 mm. The defogger 3 apparently functions as a part of the antenna due to this capacitive coupling. Especially A
For the M band, the defogger 3 also functions as a part of the AM band antenna, the effective length of the AM band antenna is increased, a large amount of received radio waves are received, and the reception sensitivity is increased.

Since a leakage current flows from the antenna conductor 6 to the vehicle body and the defogger 3, the loss from the defogger 3 is blocked by the coils 12a and 12b, which increases the reception sensitivity in the FM broadcasting frequency band (hereinafter referred to as the FM band). To do. Therefore, when it is not necessary to receive the FM band, the coils 12a and 12b may be omitted.

In the defogger 3 shown in FIG. 1,
A branch line 3a is attached to the uppermost heater line 2a of the defogger 3.
Is provided. The branch line 3a of the defogger 3 extends in the vertical direction from the vicinity of the center of the uppermost heater wire 2a as shown in FIG. 1, and branches in the horizontal direction near the adjacent portion 6a of the antenna conductor 6 in a substantially T shape. It is shaped like a circle. Since no heater current flows through the branch line 3a, noise is small, and the reception sensitivity is increased due to capacitive coupling between the antenna conductor 6 and the defogger 3.

However, the branch line 3a of the defogger 3 may have any shape as long as it has the above function, and is not limited to the shape of FIG. For example, the heater wire 2a may have a shape that extends in the vertical direction from the vicinity of the left or right and extends horizontally in the opposite direction near the adjacent portion 6a. Further, the defogger branch line 3a can be replaced with a part of the heater wire 2, and
Although a may be omitted, it is preferable to provide the branch line 3a in view of the noise described above.

Although FIG. 1 exemplifies a so-called U-shaped defogger having three busbar shapes, a so-called C-shaped defogger having two busbars as shown in FIG. 5 can also be used. In FIG. 5, 1 is a glass plate of the rear window of the automobile, and 6 is an antenna conductor.

As described above, the defogger 3 and the antenna conductor 6 are capacitively coupled at a part thereof, so that the defogger 3 and the antenna conductor 6 are on the same plane as the glass plate of the rear window, normally. Is optimally formed on the inside surface of the room. As the pattern of the antenna conductor 6, depending on the shape of the automobile, the shape, dimensions, configuration of the glass plate, long wave broadcasting, AM broadcasting, short wave broadcasting, FM broadcasting, short wave broadcasting-long wave broadcasting-AM broadcasting-FM broadcasting radio broadcasting, Also, a pattern that can obtain optimum performance as an antenna for television or other broadcasting is appropriately selected and designed.

[0021] Figure 1 is shown an example in which the antenna conductor 6 on the top of the defogger 3 in the glass plate 1, rather it may also be provided in the lower portion of the defogger 3 is not limited thereto, differential <br/> Ogga 3 of the upper and lower portions rather good be provided respectively on, the glass plate 1
It may be provided in other margins.

The connection terminals for connecting the antenna conductor 6 and the antenna cable by means of only soldering or the like, similarly to the heater line 2 of the defogger 3 described above, a conductive metal such as conductive silver paste on the glass plate surface The most common type is a print type of filaments in which a paste containing paste is printed in a predetermined pattern and baked, but the invention is not limited to this, and may be a transparent conductive film or an ultrafine conductive wire of a predetermined pattern. Good.

[0023] In the present invention, between the lead wire 22a and the lead wire 22b of the defogger 3, a high frequency band of current flow is such broadcast band to the defogger 3 from the DC power supply 10
The reactance circuit 8 is inserted so as to cut off the current. The reactance circuit 8 is composed of a heater transformer 9, coils 12a and 12b, and a condenser 11. The reactance circuit 8 can insulate the heater wire 2 of the defogger 3 and the bus bars 5a, 5b, 5c from the vehicle body ground in a high frequency manner, and the heater wire 2 and the bus bar 5a,
It is possible to prevent a receiving current in a high frequency band such as a radio broadcasting band induced in 5b and 5c from flowing to the vehicle body, and to send the induced current to the receiver without leakage.

The choke coil of the heater transformer 9 in the reactance circuit 8 has characteristics such that it has a high impedance in a high frequency band such as a radio broadcasting band and prevents magnetic residual, for example, a toroidal magnetic core (M
n-Zn ferrite) on the high-frequency choke coil was-out bifilar winding, the high-frequency choke coils are wound in a direction to cancel each other the magnetic flux of the coil generated by the current from the closed magnetic path, or a high magnetic saturation core A high-frequency choke coil using , etc. is used.

In such a high frequency choke coil,
Required inductance and self-resonant frequency and Q
In order to obtain the value, for example, the core is divided into two, the interval between the cores is adjusted, a predetermined capacitor is connected in parallel, and the coil pitch is changed.

A resistor 1 connected in parallel with the choke coil
Reference numerals 6 and 17 have a function of adjusting the selectivity of antiresonance. By reducing the value of resistors 16 and 17,
The value of Q can be reduced.

The condenser 11 in the reactance circuit 8
Is electrically short-circuited to a noisy current having a high frequency component in a high frequency band such as a radio broadcasting band. Install a filter between the reactance circuit 8 and the DC power supply 10
Influence of miscellaneous sound of the current may be prevented.

High frequency coil 12 in reactance circuit 8
a, 12b serves as a high impedance in the FM band, typically, a solenoid or not using the magnetic core using magnetic cores. These have inductive inductance in the FM band.

In some cases, a lead wire having an appropriate length can be used as the coil 12a and the like, and the same effect may be obtained depending on the arrangement of the reactance circuit 8 in the vehicle body. High-frequency choke coil of the heater transformer 9 F M bands in low self-resonance frequency, inductance loss of Unode, high frequency coils 12a, 12b to act for this.

In the example of FIG . 1 , a matching circuit 7 which is the " predetermined circuit " of the present invention is inserted at a desired position on the path between the feeding point 4 of the antenna conductor 6 and the receiver 20 such as a radio. Then, the high frequency current of the received radio wave induced in the antenna conductor 6 becomes the impedance of the matching circuit 7,
It is resonated by the input impedance of the receiver 20 and the impedance of the antenna conductor side as seen from the matching circuit, and is sent to the receiver 20.

The matching circuit 7 shown in FIG.
Although it is composed of a circuit composed of each of the elements 3, capacitor 12, 14 and resistor 15, it is not limited to this, and any circuit structure can be used as long as it is a circuit which causes a predetermined resonance. The matching circuit 7 also has a function of performing impedance matching between the input of the receiver 20 and the feeding point 4 of the antenna conductor 6. Further, the predetermined circuit
As such, one that does not have a function of impedance matching can also be used .

As described above, the antenna conductor 6 and the defogger 3 are usually formed by printing a conductive silver paste on the surface of a glass plate by printing and baking it . In this case, the adjacent part 6a and the branch line 3a which are adjacent to each other
There is a risk that printed silver will migrate between the two and the two, causing a short circuit between the two. Although the matching circuit 7 shown in FIG. 1 can prevent a direct current flowing into the input of the receiver by a condenser 12, a circuit configuration can not prevent a direct current flowing into the input of the receiver as <br/> predetermined circuit in the present invention If the above is adopted, a large current will flow in the receiver 20 due to the above migration, etc.
In order to prevent this, a DC blocking capacitor may be inserted between the feeding point 4 of the antenna conductor 6 and a predetermined circuit.

In the matching circuit 7 shown in FIG. 1, the capacitor 12 is mainly for blocking a direct current, and is not limited to the position shown in FIG. 1, but may be inserted between the feeding point 4 and the matching circuit 7.

In the matching circuit 7 shown in FIG. 1, the resistor 15 may be omitted and used. The resistor 15 has a function of flattening the reception sensitivity affected by resonance. The matching circuit is not limited to the matching circuit 7 shown in FIG. 1, and any circuit that causes resonance in the present invention can be used.

In addition to what has been described above, the adjustment of the matching circuit and the like will be described. In the present invention, due to the impedance of the choke coil and the defogger, the frequency between the LW band upper limit frequency and the half of the LW band lower limit frequency is set. Make sure that there is an anti-resonance point on the antenna conductor, insert and connect a predetermined circuit between the feeding point of the antenna conductor and the receiver, and connect the antenna conductor side from the predetermined circuit impedance and the receiver input impedance and the predetermined circuit. by the look impedance, the frequency of the center of the LW band upper limit frequency and the AM band lower limit frequency, it is necessary to make the resonance point between 1.5 times the frequency of the AM band upper limit frequency is present. If the resonance point and anti-resonance point do not exist within this range, LW
It becomes difficult for the receiving sensitivity to fall within the range of variations within several dB within the band, and the receiving sensitivity is not flat.

In order to further flatten the receiving sensitivity in the LW band by several dB, the anti-resonance point is made to exist in the LW band by the impedance of the choke coil and the defogger, and the feed point of the antenna conductor and the receiver are connected. It is desirable to insert and connect a predetermined circuit to the antenna so that a resonance point exists in the AM band by the impedance of the predetermined circuit, the input impedance of the receiver, and the impedance of the antenna conductor side viewed from the predetermined circuit. 153-220kH
anti-resonance point z is resonance point 1000~1600kHz is, it is more desirable to be present, respectively.

[0037]

In the present invention, if it is desired to have the FM band receiving function at the same time, it is preferable to design the predetermined circuit so that the output impedance of the predetermined circuit becomes low. This improves the FM band reception sensitivity. The output impedance of the given circuit should be 300Ω or less,
The range of 50 to 200Ω is more desirable. If the output impedance of the specified circuit is 300Ω or less, 300Ω
The reception sensitivity in the FM band is improved by several dB compared with the case of exceeding. When the output impedance of the predetermined circuit is within the range of 50 to 200Ω, the receiving sensitivity in the FM band is improved by several dB as compared with the case where the output impedance is outside this range.

[0039] Oite the matching circuit 7 in FIG. 1, in the AM band and LW band, the capacitor 12 is 1000 to 1000
0 pF, condenser 14 is 5 to 30 pF, coil 13
Is preferably 100 to 350 μH, and the resistance 15 is preferably 1 to 10 kΩ. On the other hand, the primary and secondary inductances of the choke coil of the heater transformer 9 connected to the defogger 3 are 1 to 20 mH in the AM band and LW band, respectively .
Each resistor 16, 17 5～50Keiomega, condenser 11 0.01～0.5Myu F, the coil 12a in the FM band,
12b is preferably set to be 0.1~5μH respectively, capacitive coupling portion between the branch line 3a of the adjacent portion 6a is preferably set to 10~1000pF in FM band and AM band.

[0040] Of course, these values are exemplary for a typical, it can be modified for optimal performance is obtained in accordance with the glass antenna device for an automobile of interest.

[0041]

With the impedance of the choke coil and the defogger, an anti-resonance point exists between the LW band upper limit frequency and half the LW band lower limit frequency, and the reactance circuit has a high impedance. The current of the received signal in the LW band induced by the current is prevented from flowing into the vehicle body, and the reception sensitivity mainly in the low band of the LW band and the AM band is improved.

A predetermined circuit is inserted and connected between the feeding point of the antenna conductor and the receiver, and the LW band is determined by the impedance of the predetermined circuit, the input impedance of the receiver, and the impedance of the antenna conductor viewed from the predetermined circuit. and the frequency of the center of the upper limit frequency and the AM band lower limit frequency, the receiving sensitivity of the high frequency side of the AM band by allowing the resonance point exists between 1.5 times the frequency of the AM band upper limit frequency Is improved. In the present invention, the stray capacitances and the like of the defogger and the wiring are also elements of anti-resonance and resonance.

[0043]

EXAMPLE In the glass antenna device for an automobile of the present invention shown in FIG. 1, the capacitor 1 in the AM band and the LW band is used.
2 was 2400 pF, the capacitor 14 was 10 pF, the coil 13 was 180 μH, and the resistor 15 was 4.7 kΩ.

On the other hand, the primary and secondary inductances of the choke coil of the heater transformer 9 connected to the defogger are 7.5 mH in the AM band and LW band, respectively , and the resistance is 1.
6 and 17 are 27 kΩ each , and the capacitor 11 is 0.
22Myu F, capacitive coupling portion between the branch line 3a of the adjacent portion 6a and a 90pF with LW band and AM band.

Further, the antenna conductor 6 is used in the LW band and the AM band.
The capacity of the antenna cable portion between the feeding point 4 of FIG. 1 and the input end of the receiver 20 was 30 pF / m. Also, FM
In the strip, the coils 12a and 12b each had a capacitance of 0.8 μH.

The results of measuring the frequency characteristics of the receiving sensitivity in the AM band and the LW band of the embodiment are shown in FIGS. 2 and 3, respectively. 2 and 3 show that the electric field strength is 6 near the glass antenna.
The receiving sensitivity obtained at 0 dBμV / m is obtained for each frequency.

As a comparative example , JP-A-2-2397.
Respectively Figure 2 the results of measuring the frequency characteristics of the receiving sensitivity of the AM band and LW band embodiments that are described in 01 JP, are shown in Figure 3. In the comparative example, the matching circuit 7 shown in FIG. 4 was used instead of the matching circuit 7 shown in FIG.

In FIG. 4, the direct current blocking capacitor 59 is 0.01 μF, the coil 53 is 300 μH, the coil 54 is 150 μH, the resistor 55 is 680 Ω, and the coil 5 is
8 is 2 μH, capacitor 56 is 27 pF, coil 57
Is 330 μH, anti-resonance is performed in the low band of the AM band, and resonance is performed in the high band of the AM band.

[0049] Note that the frequency characteristic of the receiving sensitivity of the FM band embodiment, it is variation within a few dB at FM band all-pass, was a flat frequency characteristic.

[0050]

In the present invention, because it does not use a pre-amplifier, noise is no directly amplified Ru problem, also, and problems in productivity that a poor, near the preamplifier of the glass antenna with the installation child, no gutter <br/> cormorants problem constraints on the design of the automobile occurs for space securing the preamplifier, high receiver sensitivity, low noise, non-directional reception performance It is possible to provide a glass antenna for long-wave reception of automobiles with high efficiency.

Further, there is a variation within a few dB over the entire LW band.
It can be received with a relatively flat reception sensitivity characteristic, and it can receive not only long-wave broadcasting but also AM broadcasting with high gain and low noise.
Kill at Shin. Further, if a predetermined circuit has a low impedance in the FM band, FM broadcasting can be received with high reception sensitivity and omnidirectionality.

[Brief description of drawings]

FIG. 1 is a block diagram of a glass antenna for receiving a long wave of an automobile according to the present invention.

FIG. 2 is a frequency reception sensitivity characteristic diagram in the AM band of the embodiment.

FIG. 3 is a frequency reception sensitivity characteristic diagram in the LW band of the embodiment.

FIG. 4 is a circuit diagram of a conventional matching circuit.

FIG. 5 is a front view of a defogger having a shape pattern different from that of FIG.

[Explanation of symbols]

1: Glass plate on the rear window 2: heater wire 3: Defogger 4: Feeding point of antenna conductor 6 5a, 5b, 5c: Bus bar 6: Antenna conductor 7: Matching circuit 8: Reactance circuit 9: Heater transformer

Continuation of the front page (56) References JP-A-4-365204 (JP, A) JP-A-53-59344 (JP, A) JP-A-7-111412 (JP, A) Actual Kaihei 2-90508 (JP , U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 1/32

Claims (3)

(57) [Claims] 1. A defogger of an electric heating type having a heater wire and a bus bar for feeding the heater wire to a glass plate of a rear window of an automobile, and a direct current is not transmitted and received between the defogger but a high frequency current For transmission and reception, an antenna conductor that is capacitively coupled in close proximity at a predetermined interval is provided so that a choke coil is provided between one bus bar and the battery and between another bus bar and the ground. in automotive long wave reception glass antenna which is inserted and connected, by the impedance of the choke coil and the defogger, anti-resonance point exists between half the frequency of the upper limit frequency and the long wave broadcast frequency band lower limit frequency long wave broadcast frequency band Insert a predetermined circuit between the feeding point of the antenna conductor and the receiver, and connect the impedance of the predetermined circuit and the input impedance of the receiver. The dance with a predetermined impedance seen an antenna conductor side from the circuit, and the center frequency of the long wave broadcast band upper limit frequency and the AM broadcast frequency band lower limit frequency,
Automotive long wave reception glass antenna characterized in that as the resonance point exists between 1.5 times the frequency of the AM broadcast frequency band upper limit frequency. 2. An electric heating type defogger having a heater wire and a bus bar for feeding the heater wire to a glass plate of a rear window of an automobile, and direct current is not transmitted and received between the defogger but high frequency current For transmission and reception, an antenna conductor that is capacitively coupled in close proximity at a predetermined interval is provided so that a choke coil is provided between one bus bar and the battery and between another bus bar and the ground. In the inserted long-wave receiving glass antenna for automobiles, the anti-resonance point exists in the long-wave broadcasting frequency band due to the impedance of the choke coil and defogger, and a predetermined circuit is provided between the feeding point of the antenna conductor and the receiver. By inserting and connecting the impedance of the specified circuit and the input impedance of the receiver and the impedance of the antenna conductor viewed from the specified circuit. A glass antenna for long-wave reception of an automobile, characterized by having a resonance point in the AM broadcast frequency band. Wherein by connecting a resistor in parallel with the choke coil, automotive long wave reception glass antenna according to claim 1 or 2, characterized in that to adjust the selectivity of the anti-resonance.