JPH0756495Y2 - Antenna device for car window - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an antenna device for an automobile, in which a conductor is attached to a glass surface by printing or the like.

[Conventional technology]

Generally, a rear window glass of an automobile is provided with an anti-fog heater wire. It is known that an antenna conductor for radio or TV reception is provided above or below the anti-fog region provided with the heater wire. Such an antenna conductor has an advantage that it is possible to tune the directivity, the bandwidth, etc. by freely drawing the conductor on the glass surface.
It is also well known to use the heater wire itself as an antenna conductor.

[Problems to be solved by the device]

Since the conductor length and array pitch of the heater wire are fixed,
It is impossible to tune the conductors, that is, to adjust the effective length corresponding to the bandwidth or to improve the directivity. Therefore, the broadcasting band that cannot be received by the heater wire is covered by the antenna conductor above or below the broadcasting band.

A certain amount of space is required to lay out the antenna conductor, but this portion cannot be defrosted. On the contrary, if the anti-fog region provided with the heater wire is expanded, the space for the antenna conductor is reduced, and satisfactory tuning cannot be performed.

In view of this problem, an object of the present invention is to provide an antenna device that satisfies both the expansion of the anti-fog region and the securing of a space for disposing the antenna conductor.

[Means for Solving the Problems]

The present invention provides an antenna device for an automobile window, comprising an anti-fog heater wire provided in a central heating region of the automobile window, and an antenna conductor provided in at least one of an upper portion and a lower portion of the heating region. Is tuned so as to have a higher natural frequency than the heater wire, and constitutes a closed circuit for supplying a heating current.

[Action]

While using the antenna conductor as the heater conductor to form a closed circuit that allows the heater current to flow, the antenna conductor is responsible for a band that is sufficiently higher than the reception band of the heater wire, and it is possible to improve the reception characteristics by tuning the conductor layout. There is.

〔Example〕

FIG. 1 is a diagram showing an arrangement of conductors on an automobile window glass and an electric system showing an embodiment of an antenna device for an automobile window of the present invention.

On the rear window glass 1, a large number of heater wires 2 are provided separately in two groups, namely, upper and lower groups. Bus bar 3a,
Power supply lines 5a and 5b are connected to 3b, and a heating current is supplied from the main power source + B to the power supply line 5a via the high frequency choke coil 6a. The power supply line 5b connected to the bus bar 3b is grounded via the choke coil 5b.

The choke coils 6a and 6b are coupled to each other in the demagnetizing direction through the same core, and are used without saturating the core even with a large heating current. Since the impedances of the choke coils 6a and 6b are extremely large in the radio broadcasting band, it is possible to increase the ground impedance of the heater wire 2 and use it as an antenna. The reception band of the heater wire 2 is the AM broadcast band, and the reception signal is transmitted to the AM radio via the coupling capacitor 7a and the coaxial cable 7 connected to the terminals of the relay bus 4.

An antenna conductor 8 tuned for FM broadcast reception is provided in the upper margin of the anti-fog area where the heater wire 2 is provided.
Is provided. The antenna conductor 8 has a horizontally long rectangular wiring shape, and a pair of power receiving terminals 9a and 9b are provided at the center position of the long side (horizontal direction) along the upper side of the window glass 1. The power receiving terminal 9a is connected to the core wire of the coaxial cable 11 via the DC cut capacitor 10, and the power receiving terminal 9b is connected to the outer conductor of the coaxial cable 11. Therefore, the antenna conductor 8 operates as an unbalanced antenna with one side grounded. The AM reception signal obtained from the antenna conductor 8 is supplied to the FM radio via the coaxial cable 11.

The antenna conductor 8 has its long sides and short sides set to 1600 mm × 30 mm so that it can receive FM broadcast radio waves with high sensitivity. At the same time, the conductor 8 is viewed from the power receiving terminals 9a and 9b so that the antenna conductor 8 can also be used as a defrosting heater wire.
Constitutes a closed circuit. The power receiving terminal 9a is connected to the positive power supply line 12a branched from the power supply line 5a, and the power receiving terminal 9b is connected to the ground side power supply line 12b branched from the power supply line 5b. Therefore, the antenna conductor 8 has a power receiving terminal.
A heating current flows in the direction from 9a to 9b, the temperature of the glass surrounded by the conductor 8 and its surroundings becomes high, and the haze is removed.

FIG. 2 shows a modified example of the heating current circuit. In this example, the heating current is supplied to the antenna conductor 8 via the choke coils 6a and 6b, and the heater wire 2 is supplied from the power source without the choke coils 6a and 6b. The heating current is directly supplied via the power supply lines 5a and 5b. In this power supply circuit, the choke coils 6a and 6b are
Dedicated to FM band. In the AM band, it is necessary to increase the inductance of the choke coil, the stray capacitance increases as the number of windings increases, and in the FM band, the leakage through the choke coil cannot be ignored. However, this problem can be avoided by using the FM choke coil. Note that, in FIG. 2, a choke coil dedicated to the AM band may be further inserted in the power supply lines 5a and 5b.

FIG. 3 shows an example in which the antenna conductor 8 is fed laterally (short side). Terminals 9a and 9b are provided on the short sides of the rectangular antenna conductor 8 to supply heating current and collect received power. Further, in this example, the auxiliary element 8a is drawn out along the heater wire 2 from the end of the antenna conductor 8 opposite to the terminals 9a and 9b to improve the reception characteristic of the antenna conductor 8.

FIG. 4 shows still another example, which is the ground side bus bar 3b of the heater wire 2.
Of the antenna conductor 8 shown in FIG.
Connected to 9b. In this example, the power supply line 12b in FIG. 3 is unnecessary.

FIG. 5 shows the antenna conductor 8 including a plurality of parallel horizontal conductors 8b and 8c.
It is an example configured with. The number of these horizontal conductors can be increased or decreased for tuning, and a parallel connection of the conductors can also form a closed circuit for the heating current.

In the embodiment shown in FIGS. 1 to 4 described above, the antenna conductor 8 can be provided in the lower margin of the anti-fog region of the heater wire 2.

[Effect of device]

As described above, the automobile window antenna of the present invention uses the antenna conductor provided outside the anti-fog region as a heater wire, and forms a closed circuit of the heater current, and the antenna band is higher than the reception band of the heater wire in the anti-fog region. It is characterized in that the antenna conductor is responsible for a high band.

Therefore, according to the present invention, the anti-fog region can be expanded to ensure a sufficient rear view, and the performance as a high frequency antenna is not deteriorated.

[Brief description of drawings]

FIG. 1 is a front view of a rear window glass and an electric system showing an embodiment of a vehicle window antenna device of the present invention, and FIGS. 2 to 4 are views similar to the first embodiment showing different embodiments, respectively. , FIG. 5 is a diagram showing a modification of the antenna conductor. In the reference numerals used in the drawings, 1 ... rear window glass 2 ... heater wire 3a, 3b ... bus bar 4 ... relay bus bar 5a, 5b ... feeder line 6a, 6b ... choke coil 7 ... coaxial cable 8 …… Antenna conductor 8a …… Auxiliary conductors 9a, 9b …… Power receiving terminal 10 …… Capacitor 11 …… Coaxial cable 12a, 12b …… Feed line.

Claims (1)

[Scope of utility model registration request] 1. An anti-fog heater wire provided in a central heating region of an automobile window, and an antenna conductor provided in at least one of an upper portion and a lower portion of the heating region, wherein the antenna conductor is the heater wire. An antenna device for an automobile window, which is tuned to have a higher natural frequency than that of the above, and which constitutes a closed circuit for supplying a heating current.