JP2003037419A - Glass antenna apparatus for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost and compact glass antenna apparatus for automobiles. SOLUTION: A filter circuit 18 is provided between a defogger 3 and a DC power supply 10 and has the function of attenuating frequencies that are lower than 50 MHz. An antenna conductor has a lattice-shaped element 4 and horizontal elements 15, 16, and 17, a feed point 6 is connected to the left side of the lattice-shaped element 4, the horizontal elements 15, 16, and 17 are connected to the right side of the lattice-shaped element 4 and to the right-side end section of the horizontal elements 15, 16, and 17 is connected by a vertical connection element.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass antenna device for automobiles suitable for receiving radio and television broadcasts. Conventionally, a long wave broadcasting band (150 to 280 kHz)
z) Broadcast bands of less than 50 MHz such as medium wave broadcast band (520 to 1700 kHz) and short wave broadcast band (2.3 to 26.1 MHz), and broadcast bands of 50 MHz or more such as Japanese FM broadcast band (76 to 90 MHz). 2 is known as a glass antenna device for automobiles that receives the above. In the conventional example shown in FIG. 2, the antenna conductor provided on the rear window glass plate 1 and the defogger 3 are placed close to each other and capacitively coupled (usually 50 pF or more), and between the defogger 3 and the DC power source 10. The radio wave signal excited by the defogger 3 by connecting the choke coil 9 is transmitted to the receiver 20 via the capacitive coupling, the antenna conductor, the feeding point 6 and the preamplifier 17 to improve the sensitivity. However, the conventional example shown in FIG. 2 has a problem that it is susceptible to vehicle noise such as engine noise when receiving a long wave broadcast band, a medium wave broadcast band, and a short wave broadcast band. Furthermore, in order to receive the long wave broadcasting band, the inductance value of the choke coil 9 must be 1 to 10 mH,
There is a problem that the cost of the choke coil 9 is increased, and the entire apparatus becomes large. SUMMARY OF THE INVENTION An object of the present invention is to provide a glass antenna device for an automobile that eliminates the above-mentioned drawbacks of the prior art. According to the present invention, a plurality of heater wires and an electrically heated defogger having a plurality of bus bars for supplying power to the heater wires are provided on a rear window glass plate of an automobile. The antenna conductor and the feeding point of the antenna conductor are provided outside the defogger area of the rear window glass plate, and between one bus bar and the DC power source and / or between another bus bar and the ground. Is provided with a filter circuit.
In a glass antenna device for an automobile that receives a broadcast band of less than 0 MHz and a broadcast band of 50 MHz or more, the filter circuit has a function of attenuating all or a part of frequencies less than 50 MHz, and the antenna conductor includes a lattice element and a plurality of antenna conductors. Horizontal elements, and a feeding point is connected to the right or left side of the grid element, and a plurality of horizontal elements are connected to the side opposite to the feeding point of the grid element. Provided is a glass antenna device for an automobile, wherein at least two of the elements are connected to each other by the vertical connection element at or near the ends of the horizontal elements on the opposite side of the grid-like elements. To do. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of a glass antenna device for an automobile according to the present invention. The glass antenna device for an automobile shown in FIG. 1 includes, for example, a long wave broadcast band, a medium wave broadcast band,
Receives shortwave and Japanese FM broadcast bands. In FIG. 1, 1 is a rear window glass plate of an automobile, 2 is a heater wire, 2a (dashed line) is a short-circuit wire for connecting the heater wire, 3 is a defogger, 4 is a lattice element, 4a
Is a first vertical element, 4b is a second vertical element, 4c is a third vertical element, 5a and 5b are bus bars, 6 is a feeding point of the antenna conductor, 7 is an antenna peripheral circuit, 8a is a vertical connection element, 8b Is an upper extension of the vertical connection element, 8c is a lower extension of the vertical connection element, 10 is a DC power source, 11 is a capacitor, 12 is a coil, 15 is a first horizontal element, 16 is a second horizontal element, 17 Is the third horizontal element, 18 (inside the broken line) is the filter circuit, 20 is the receiver, 22 (dashed line) is the fourth horizontal element, 23 (dashed line) is the fifth horizontal element, and 24 (dashed line) is the auxiliary connection Is an element. As shown in FIG. 1, a plurality of heater wires 2
The rear window glass plate 1 is provided with an electrically heated defogger 3 having bus bars 5 a and 5 b for supplying power to the heater wire 2. An antenna conductor and a feeding point 6 are provided outside the area of the defogger 3 on the rear window glass plate 1. It is preferable that the antenna conductor and the defogger 3 are not capacitively coupled or capacitively coupled at 50 pF or less.
The capacity of capacitive coupling between the antenna conductor and the defogger 3 is 50
When it exceeds pF, it is S compared to the case of 50 pF or less.
/ N ratio becomes worse. A reception signal excited on the antenna conductor is sent to the receiver 20 via the feeding point 6 and the antenna peripheral circuit 7. A DC current is supplied to the defogger 3 from the DC power supply 10. The antenna conductor includes a lattice element 4 and a plurality of horizontal elements 15, 16 and 17.
A feeding point 6 is connected to the right or left side of the grid-like element 4. On the opposite side of the grid element 4 to which the feeding point 6 is connected, a plurality of horizontal elements 15, 16,
17 is connected. Ends of the horizontal elements 15, 16, and 17 on the opposite side to the lattice elements are connected by a vertical connection element 8a. An upper extending portion 8b extending from the upper portion of the vertical connecting element 8a toward the left and right center of the rear window glass plate 1 may be provided.
A lower extending portion 8c that extends from the lower portion of the rear window glass plate 1 toward the left and right center of the rear window glass plate 1 may be provided. The vertical connection element 8a contributes to improving the sensitivity of a broadcast band of 50 MHz or higher. The upper extension 8b and the lower extension 8c are provided to adjust the length of the conductor of the vertical connection element 8a. The conductor length of the vertical connection element 8a (the conductor length including the upper extension 8b and the lower extension 8c) is 50.
When the wavelength of the center frequency of a desired high frequency broadcast band that is a broadcast band of MHz or higher is λ _M , (λ _M /4)×0.5×
K to (λ _M /4)×1.5×K is preferable.
When the frequency is within this range, the sensitivity of a desired high-frequency broadcast band is improved as compared with the case where the frequency is outside this range. Note that K is a glass shortening rate and is usually 0.64. In the example of FIG. 1, horizontal elements 15, 1
A plurality of horizontal elements 22 and 23 are connected to the opposite side of the grid-like element 4 to which the feeding point 6 is connected, below 6 and 17. Horizontal elements 22, 2
3 is provided as necessary, and contributes to improving the sensitivity of a broadcast band of 50 MHz or higher. In order to finely adjust the sensitivity, the horizontal elements 22 and 23 may be connected to the ends of the horizontal elements 22 and 23 on the side opposite to the lattice-like elements by the vertical connection element 24. The conductor lengths of the horizontal elements 22 and 23 are (λ _M /4)×0.6×K to (λ _M / 4) ×, respectively.
It is preferable to set it as 1.3 * K. When the frequency is within this range, the sensitivity of a desired high-frequency broadcast band is improved as compared with the case where the frequency is outside this range. By adjusting the conductor lengths of the horizontal elements 22 and 23, it is possible to adjust the frequency-sensitivity characteristics of a desired high-frequency broadcast band. Furthermore, the provision of the horizontal elements 22 and 23 improves the sensitivity of a broadcast band of less than 50 MHz. The lateral width of the lattice-like element 4 (corresponding approximately to the distance between the second vertical element 4b and the third vertical element 4c) is (λ _M /4)×0.5×K˜(λ _M / 4). )
It is preferable to set it as * 1.5 * K. When the frequency is within this range, the sensitivity of a desired high-frequency broadcast band is improved as compared with the case where the frequency is outside this range. The conductor lengths of the horizontal elements 15, 16, and 17 are (λ _M /4)×0.5×K to (λ _M /
4) It is preferable to set it as * 1.3 * K. When the frequency is within this range, the sensitivity of a desired high-frequency broadcast band is improved as compared with the case where the frequency is outside this range. Horizontal element 15, 1
The distance between 6 and 17 is preferably 10 to 50 mm. Within this range, the horizontal elements 15, 16, 1
Each of 7 is capacitively coupled, and the sensitivity of the desired high frequency broadcast band is improved. A filter circuit 18 is inserted and connected between the bus bar 5b and the DC power source 10. Since it is easy to attenuate noise and is inexpensive and preferable, it is configured in this manner in FIG. 1. However, the present invention is not limited to this, and a filter circuit may be inserted and connected between the bus bar 5a and the ground, or the bus bar 5b. A filter circuit may be inserted and connected between the power supply 10 and the DC power supply 10 and between the bus bar 5a and the ground. In the present invention, a broadcast band of less than 50 MHz and a broadcast band of 50 MHz or more are received. If it is a broadcast band of less than 50 MHz, it may be one broadcast band or a plurality of broadcast bands. Moreover, if it is a broadcasting band of 50 MHz or more, 1
There may be one broadcast band or a plurality of broadcast bands. The filter circuit 18 has a function of attenuating all or a part of frequencies below 50 MHz. In the example of FIG. 1, the filter circuit 18 includes a capacitor 11 and a coil 12.
However, the circuit configuration is not limited to the circuit configuration illustrated in FIG. 1 as long as it has a function of attenuating all or part of the frequency lower than 50 MHz. As shown in FIG. 1, feed point 6 and receiver 20
Between the two, the antenna peripheral circuit 7 is inserted and connected.
The antenna peripheral circuit 7 is a circuit provided as necessary. The antenna peripheral circuit 7 is not provided, and the feeding point 6 and the receiver 2 are not provided.
0 may be directly connected by a cable. The antenna peripheral circuit 7 includes a preamplifier circuit, an impedance matching circuit, a resonance circuit, and the like, and is not particularly limited, but a preamplifier circuit is preferable in order to obtain flat sensitivity characteristics. A short-circuit wire 2a for short-circuiting the heater wire 2 at portions other than the bus bars 5a and 5b is provided as necessary and has a function of stabilizing the impedance of the defogger 3. The antenna conductor, heater wire 2, bus bars 5a, 5b and short-circuit wire 2a are usually made of silver paste or the like.
It is formed by printing and baking a paste containing a conductive metal on the inner surface of the rear window glass plate 1. But,
Without being limited to this forming method, a linear body or a foil-like body made of a conductive material such as copper may be formed on the vehicle inner surface or the vehicle outer surface of the rear window glass plate 1, and the rear window glass plate 1
It may be provided inside itself. EXAMPLES Examples (Example 1) and Comparative Examples (Example 2) will be described below. Example 1 A glass antenna device for an automobile as shown in FIG. 1 was produced using a rear window glass plate of the automobile. Horizontal elements 22 and 23 were provided, and the vicinity of the ends of the horizontal elements 22 and 23 was connected by a vertical connection element 24. The value of the coil 12 was 100 μH, the value of the capacitor 11 was 10 μF, and the capacitance due to capacitive coupling between the antenna conductor and the defogger 3 was 20 pF. The antenna peripheral circuit 7 was not provided. The horizontal width of the grid element 4 is 520 mm, the vertical width of the grid element 4 is 170 mm, the distance between the first vertical element 4a and the second vertical element 4b is 250 mm, and the first vertical element 4a and the third vertical element 4c Spacing 270 mm, horizontal element 15 conductor length 515 mm, horizontal element 16 conductor length 520 mm, horizontal element 17 conductor length 525 mm, horizontal element 15 and horizontal element 16 gap 30 mm, horizontal element 16 and horizontal element 17 gap 30 mm The conductor length of the upper extending portion 8b is 290 mm, the total length of the conductor length of the vertical connecting element 8a and the conductor length of the lower extending portion 8c is 155 mm, the conductor length of the horizontal element 22 is 380 mm, the conductor length of the horizontal element 23 is 350 mm, Horizontal element 17 and water Distance 30mm of the element 22, spacing 40mm between the horizontal elements 22 and horizontal elements 23, gap 40mm between the heater line 2 of the horizontal element 23 and highest. FIG. 4 shows the frequency in the long wave broadcasting band as a solid line.
Shows sensitivity characteristics. FIG. 5 shows the frequency-sensitivity characteristics in the medium wave broadcasting band with a solid line. FIG. 6 shows the frequency-sensitivity characteristics in the FM broadcast band with a solid line. The sensitivity shown in FIG. 6 is obtained when the plane of polarization when the direction of the electric field of the incoming radio wave is inclined 45 degrees with respect to the ground, and is the average sensitivity when the vehicle is rotated once. is there. The sensitivity of Example 2 in FIG. 6 is the same. The short-wave broadcasting band was also received and received well. The solid line in FIG. 3 shows the frequency-attenuation characteristic of the filter circuit 18. Example 2 A glass antenna device for an automobile as shown in FIG. 2 was manufactured using a rear window glass plate of the automobile. The inductance value of the choke coil 9 is 2.0 mH on both the primary side and the secondary side, and the capacitive coupling between the antenna conductor and the defogger 3 is 100 pF. The broken line in FIG. 3 shows the frequency-attenuation characteristic of the choke coil 9. Compared to Example 1, there were many noises in the long wave broadcast band, medium wave broadcast band and short wave broadcast band, and it was difficult to hear. 30d
When the S / N ratio was compared under an electric field strength of B μV / m, Example 1 was 5 dB larger than Example 2 at 200 kHz, 1000 kHz, and 9.5 MHz. FIG. 4 shows frequency-sensitivity characteristics in the long wave broadcasting band by broken lines. FIG. 5 shows the frequency-sensitivity characteristics in the medium wave broadcasting band by broken lines. FIG. 6 shows frequency-sensitivity characteristics in the FM broadcast band by broken lines. In the present invention, since the capacity due to the capacitive coupling between the antenna conductor and the defogger 3 is small, the long wave broadcasting band,
Less susceptible to vehicle noise such as engine noise in medium and short wave broadcast bands. Furthermore, since the choke coil is not used, the glass antenna device for automobiles can be made inexpensive and downsized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an embodiment of an automotive glass antenna device of the present invention. FIG. 2 is a configuration diagram of a conventional example. 3 is a frequency-attenuation characteristic diagram of the filter circuit 18 in Example 1 and the choke coil 9 in Example 2. FIG. 4 is a frequency-sensitivity characteristic diagram in the long wave broadcasting band of Examples 1 and 2. FIG. FIG. 5 is a frequency-sensitivity characteristic diagram in the medium wave broadcasting band of Example 1 and Example 2; 6 is a frequency-sensitivity characteristic diagram in the FM broadcast band of Example 1 and Example 2. FIG. [Description of Symbols] 1: Rear window glass plate of automobile 2: Heater wire 3: Defogger 4: Lattice-like element 6: Feed point 5a, 5b of antenna conductor: Bus bar 7: Peripheral circuit 9: Choke coil 10: DC power supply 11: Capacitor 12: Coil 18: Filter circuit

Claims (1)

What is claimed is: 1. An electric heating type defogger having a plurality of heater wires and a plurality of bus bars for supplying electric power to the heater wires is provided on a rear window glass plate of an automobile. The antenna conductor and the feeding point of the antenna conductor are provided outside the defogger area of the glass plate, and a filter circuit is provided between one bus bar and the DC power source and / or between another bus bar and the ground. Broadcast bands below 50 MHz and 5
In a glass antenna device for an automobile that receives a broadcast band of 0 MHz or higher, the filter circuit has a function of attenuating all or part of a frequency less than 50 MHz, the antenna conductor includes a lattice element and a plurality of horizontal elements, A feeding point is connected to the right or left side of the grid element, and a plurality of horizontal elements are connected to the opposite side of the grid element, and at least two of the plurality of horizontal elements are connected. As for the book, a glass antenna device for an automobile, characterized in that the ends of the horizontal elements on the side opposite to the lattice elements or the vicinity of the ends are connected by a vertical connection element.