JPH0349447Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a glass antenna, and in particular to a glass antenna that prevents noise generated in a power supply circuit from being induced in the antenna conductor via the heating conductor. It is suitable for use in antennas.

[Summary of the idea]

A ground potential band is used to separate the heating conductor used to remove fogging from the surface of window glass and the antenna conductor that induces received power to be supplied to radio wave equipment installed inside the vehicle. Afterwards,
This is a glass antenna designed to reduce noise induced from the heating conductor side to the antenna conductor side.

[Conventional technology]

2. Description of the Related Art Conventionally, it has been known that a rear window glass of an automobile is provided with a plurality of anti-fog heating conductive wires and an antenna wire for radio or TV reception. For example, a plurality of medium wave antenna wires and very high frequency antenna wires are provided above the heating conductive wire in parallel with the horizontal plane, and these antenna wires are connected to each other by the conductive wire. antenna is used.

In the glass antenna configured in this manner, the antenna wire and the heating conductive wire are capacitively coupled, and the antenna wire receives received wave power induced by the heating conductive wire. In addition, the heating conductive wire is energized by a power supply device installed in the vehicle to generate heat and remove fog that occurs on the surface of the window glass.

[Problem that the invention attempts to solve]

If the antenna wire and the heating conductive wire are capacitively coupled in this manner, noise generated in the power supply circuit will be guided to the antenna wire via the heating conductive wire.

Furthermore, if alternating current or boosted direct current is used as a heating power source, noise will be generated on radios and televisions due to harmonics mixed into the alternating current power source or boosted direct current power source. Therefore, conventional glass antennas equipped with a defogging function cannot practically use alternating current or boosted direct current, which has many harmonics.

Furthermore, if the supply voltage is increased when direct current is used, the noise level also increases accordingly, so there is a limit to how high the supply voltage can be raised.

In view of the above problems, the present invention aims to reduce the noise induced from the heating conductor side to the antenna conductor side.

[Means for solving problems]

The glass antenna of the present invention has a heating conductor 2 that removes fogging that occurs on the surface of an automobile window glass.
, an antenna conductor 6 that induces received power to be supplied to radio wave use equipment installed in the automobile, and a ground conductor 14 that partitions the heating conductor 2 and the antenna conductor 6 with a ground potential. are doing.

[Effect]

A ground conductor 14 provided between the heating conductor 2 and the antenna conductor 6 forms a ground potential band between the heating conductor 2 and the antenna conductor 6. This ground potential band shields noise radiated from the heating conductor 2 and prevents noise from being induced from the heating conductor 2 to the antenna conductor 6.

〔Example〕

FIG. 1 is a front view and an electric circuit diagram of a rear window glass of an automobile showing an embodiment of the present invention. 1st
As shown in the figure, a heating conductor 2 is provided on a rear window glass 1 of an automobile. This heating conductor 2 generates heat when a heating current flows to remove fogging generated on the surface of the rear window glass 1.

In this example, MO _x −Ag is used as the heating conductor 2.
−MO _x (MO _x = SnO ₂ , ZnO, In ₂ O ₃ , ITO, TiO ₂
A transparent conductive film 11 consisting of three layers (e.g.) is deposited by sputtering or the like. Bus bars 3a and 3b are provided at both left and right ends of the transparent conductive film 11, and heating current is supplied through lead wires 4 and 5 connected to these bus bars 3a and 3b, respectively.

Since the resistance of the transparent conductive film 11 is relatively high, a high voltage of about 40 V, for example, is required to quickly remove fogging. The example shown in Figure 1 is
The DC-AC inverter 13 converts the direct current of the battery 12 into
It converts 12V to AC and boosts it to obtain a voltage of 40V. Note that the choke coil 15 interposed between the lead wires 4 and 5 and the decoupling capacitor 16 interposed between the lead wire 4 and the ground point attenuate noise generated in the power supply circuit and leaking to the heating conductor 2. It is designed to let you do so.

For example, a medium wave antenna conductor 6 with a transparent conductive film 11 attached thereto is provided on the upper side of the heating conductor 2, and the received output is sent to a preamplifier 9 via a coaxial cable 8 coupled to a feed point 7. It is derived, amplified here, and then installed inside the car.
Supplied to AM radio.

A grounding conductor 14 made of a transparent conductive film 11 formed in a strip shape is provided between the heating conductor 2 and the antenna conductor 6, and both ends of the grounding conductor 14 are connected to a grounding point (such as the body of a car). There is. As a result, a ground potential band is formed between the heating conductor 2 and the antenna conductor 6, and the capacitive coupling between the heating conductor 2 and the antenna conductor 6 is broken. Therefore, noise generated in the heating conductor 2 is prevented from being guided to the antenna conductor 6, thereby preventing noise from the power supply circuit or the like from being mixed into radio reception sound.

As a result, it is possible to use alternating current or boosted direct current as the heating current, and the transparent conductive film 11, which has good rearward visibility but has a relatively high resistance value, can be used as a heating conductor for a glass antenna. It becomes possible.

Note that as the transparent conductive film 11, a single layer film such as SnC ₂ or In ₂ O ₃ may be used instead of the multilayer film as described above. Further, the antenna conductor 6 and the ground conductor 14 may be printed and fired.

FIG. 2 is a front view of a glass antenna showing another embodiment, and in this example, a heating conductive wire group 19 is formed by attaching a plurality of heating conductive wires 18 at predetermined intervals in the horizontal direction. It is used as a heating conductor 2. And on the upper side of this heating conductive wire group 19
An antenna wire group 20 for receiving FM radio frequency is attached, and a ground conductor 14 whose left and right ends are connected to a ground point is attached between it and the heating conductive wire group 19.

Figure 3 is a graph that compares the noise level when receiving radio waves with a frequency of 76 MHz to 90 MHz with the reference value, with the noise level when the grounding conductor 14 is not provided as a reference value of 0 [bB]. . As can be seen from this graph, by providing the ground conductor 14, the noise induced from the heating conductor 2 to the antenna conductor 6 can be effectively reduced.

4 to 6 show modified examples, and in FIG. 4, antenna conductors 6 made of conductive wires are attached to the upper and lower sides of the heating conductive wire group 19, respectively. A ground conductor 14 is provided between each antenna conductor 6 and the heating conductive wire group 19.

In FIG. 5, antenna conductors 6 are provided on the upper and lower sides of the heating conductive wire group 19, respectively, as in the example shown in FIG. An example is shown enclosed in .

The example shown in FIG. 6 shows an example of a glass antenna designed to receive television radio waves, in which a television antenna element 23 is provided above a group of heating conductive wires 19 provided on the rear window glass 1, and Television antenna elements 24 and 25 are similarly provided on the quarter window glasses 26 and 27 and used for the diversity reception system. Ground conductors 14 made of a transparent conductive film are disposed on the four sides of the rear window glass 1, and also between the heating conductive wire group 19 and the television antenna element 23. In addition, each arcuator window glass 26,
A ground conductor 14 is provided on the upper side and adjacent to the rear window glass 1 on the upper side.

[Effect of idea]

As mentioned above, in this invention, the ground conductor is placed between the heating conductor and the antenna conductor to create a ground potential band between them, so that the noise generated from the heating conductor is transferred to the antenna conductor side. This can effectively prevent the generation of noise even when AC or boosted DC with many harmonics is used as the power source for the heating conductor.

In addition, increasing the applied voltage to the heating conductor increases the noise level, but this effect can be reduced, so even if a heating conductor that requires a high applied voltage, such as a transparent conductive film, is used, the same glass It becomes possible to attach an antenna conductor to the surface.

[Brief explanation of the drawing]

Fig. 1 is a front view and electrical circuit diagram of a rear window glass of an automobile showing an embodiment of the present invention, Fig. 2 is a front view of a rear window glass of an automobile showing a modified example, and Fig. 3 is the same as Fig. 2. The graphs showing the noise level of the glass antenna shown in FIGS. 4 to 6 are front views of the rear window glass of an automobile showing other modifications, respectively. In addition, in the symbols used in the drawings, 1...rear window glass, 2... heating conductor, 6... antenna conductor, 14... grounding conductor.

Claims (1)

[Scope of utility model registration request] A heating conductor that removes fogging that occurs on the surface of an automobile window glass, an antenna conductor that induces received power to be supplied to radio wave-using equipment installed in the automobile, and a combination of the heating conductor and the antenna conductor. A glass antenna comprising a ground conductor that is separated by a ground potential.