JP2004040144A - On-glass antenna for automobile rear window - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly sensitive on-glass antenna for an automobiles rear window glass in which anti-fog process is applied to an upper part of the rear window glass plate. <P>SOLUTION: A first antenna element 4 is extended from a feeding point 3 toward a direction of the horizontal center of the rear window glass plate 1, and a second antenna element 15 is extended from the feeding point 3 downward along a right side edge of the rear window glass plate 1 and then extended while being curved in the direction of the horizontal center of the rear window glass plate 1, a third loop antenna element 6 is connected to the tip of the second antenna element 15, a fifth antenna element having a nearly horizontal part is connected to the upper part of the third antenna element 6, and a fourth antenna element 9 is extended to the right from an upper right part of the third antenna element 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a Japanese radio FM broadcast band (76 to 90 MHz), a US radio FM broadcast band (88 to 108 MHz), an AM broadcast band (530 to 1605 kHz), and a long wave broadcast band (LW broadcast band) (150 to 280 kHz). The present invention relates to a rear window glass antenna for automobiles suitable for reception of light. Hereinafter, the Japanese radio FM broadcast band and the US radio FM broadcast band are simply referred to as FM broadcast bands.
[0002]
[Prior art]
Conventionally, the rear window glass antenna for automobiles shown in FIG. 5 has been used for receiving FM broadcast band, AM broadcast band and long wave broadcast band. In this conventional example, an electrically heated defogger having a plurality of heater wires 2, an antenna conductor 31 capacitively coupled to the defogger, and a feeding point 3 of the antenna conductor 31 are provided on the rear window glass plate 1 of the automobile. A choke coil 21 is connected between the bus bars 5a and 5b and the DC power source 22.
[0003]
The choke coil 21 has a high impedance in the AM broadcast band, and a direct current flows from the DC power supply 22 to the defogger, but the received signal current in the AM broadcast band is blocked by the choke coil 21. Since the antenna conductor and the heater wire 2 are capacitively coupled, the reception signal current in the AM broadcast band excited by the antenna conductor 31 flows to the defogger. However, this blocking makes it difficult to leak into the vehicle body via the defogger. Further, the reception signal current in the AM broadcast band excited by the defogger is also difficult to leak into the vehicle body.
[0004]
However, in this conventional example, since the defogger is not provided on the upper portion of the rear window glass plate 1, there is a problem that the upper portion of the rear window glass plate 1 cannot be fogged. Further, in order to receive the LW broadcast band, the choke coil 21 having a large inductance value is required, and there is a problem that the cost is increased.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to provide a rear window glass antenna for automobiles that eliminates the above-mentioned drawbacks of the prior art and has good sensitivity.
[0006]
[Means for Solving the Problems]
In the present invention, an electrically heated defogger having a plurality of heater wires and a plurality of bus bars for supplying power to the heater wires is provided on a rear window glass plate of an automobile, and a rear window glass other than the area of the defogger An antenna conductor and a feeding point of the antenna conductor are provided in the lower margin of the plate, and a filter circuit is connected between one bus bar and a DC power source and / or between another bus bar and the ground. In the automotive rear window glass antenna
The filter circuit has a function of attenuating or blocking a frequency of at least one frequency band selected from a medium wave broadcast band and a long wave broadcast band,
The antenna conductor includes a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element,
Seen from the inside or outside of the car,
The feeding point is arranged near the right edge of the lower margin of the rear window glass plate,
The first antenna element is arranged along the lowermost heater line from the feed point so that it is not easily capacitively coupled to the lowermost heater line by medium wave broadcasting and is capacitively coupled to the FM broadcasting band. Being extended toward the left and right central direction of the rear window glass plate,
The second antenna element is extended substantially downward along the right edge of the rear window glass plate from the feeding point, and is bent and extended in the right and left central direction of the rear window glass plate in the vicinity of the lower right corner of the rear window glass plate. And
A loop-shaped third antenna element is connected to the tip of the second antenna element,
The fourth antenna element provides a rear window glass antenna for an automobile, characterized in that the fourth antenna element extends from the upper right part or the vicinity of the upper right part of the third antenna element substantially to the right.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of an automotive rear window glass antenna of the present invention. FIG. 2 is a configuration diagram of an embodiment different from FIG. 1 of the rear window glass antenna for automobiles of the present invention.
[0008]
1 and 2, 1 is a rear window glass plate of an automobile, 2 is a heater wire, 2a is a lowermost heater wire, 2b is a short-circuit wire, 3 is a feeding point of an antenna conductor, 4 is a first antenna element, 5a 5b is a bus bar, 6 is a third antenna element, 7 is a substantially vertical portion of the fifth antenna element, 8 is a substantially horizontal portion of the fifth antenna element, 9 is a fourth antenna element, and 10 (dotted line) is A sixth antenna element provided as necessary, 11 is a capacitor, 12 is a coil, 15 is a second antenna element, 22 is a DC power source, 24 is a region where a high-mount stop lamp of the rear window glass plate 1 is provided, Reference numeral 25 denotes a hole of a rear wiper provided in the rear window glass plate 1, and 26 denotes a filter circuit.
[0009]
In FIGS. 1 and 2, an electrically heated defogger having a plurality of heater wires 2 and bus bars 5 a and 5 b for supplying power to the heater wires 2 is provided on the rear window glass plate 1. The antenna conductor and the feeding point 3 of the antenna conductor are provided in the lower margin of the rear window glass plate 1 other than the area of the defogger, and the filter circuit 26 is connected between the bus bar 5 b and the DC power supply 22. .
[0010]
The antenna conductor includes a first antenna element 4, a second antenna element 15, a third antenna element 6, and a fourth antenna element 9. The feeding point 3 is disposed in the vicinity of the right edge of the lower margin of the rear window glass plate 1.
[0011]
The first antenna element 4 is capacitively coupled from the feed point 3 along the lowermost heater wire 2a and to the lowermost heater wire 2a so as not to be capacitively coupled to the lowermost heater wire 2a by medium wave broadcasting, and in the FM broadcasting band. The rear window glass plate 1 is arranged at such a position and extends toward the left and right central direction.
[0012]
The second antenna element 15 extends substantially downward from the feeding point 3 along the right edge of the rear window glass plate 1, and in the vicinity of the lower right corner of the rear window glass plate 1, the left and right central direction of the rear window glass plate 1. It is bent and stretched.
[0013]
A third antenna element 6 having a substantially square loop shape is connected to the tip of the second antenna element 15, and a substantially T-shaped fifth antenna element is formed on the upper portion of the third antenna element 6. It is connected. The substantially horizontal portion 8 of the fifth antenna element is arranged at a position where it is difficult to be capacitively coupled to the lowermost heater wire 2a by medium wave broadcasting and capacitively coupled by the FM broadcasting band. The fifth antenna element may be provided as necessary, and the shape of the fifth antenna element may be a substantially inverted L shape. The fourth antenna element 9 extends from the upper right part of the third antenna element 6 to the substantially right side.
[0014]
The conductor length of each of the first antenna element 4 and the fourth antenna element 9 is 0.5 (λ _M / 4) × K to 1.2 (where the wavelength of the center frequency of the FM broadcast band is λ _M. It is preferable that λ _M / 4) × K. When it is within this range, the sensitivity of the FM broadcast band is improved as compared to when it is outside this range. Note that K is a glass shortening rate and is usually 0.64.
[0015]
Conductor length of the second antenna element 15 when the wavelength of the center frequency of the FM broadcast band and lambda _M, and _{0.9 (λ M /4)×K~1.5(λ M / 4} ) × K It is preferable. When it is within this range, the sensitivity of the FM broadcast band is improved as compared to when it is outside this range.
[0016]
When the maximum length of the horizontal width of the third antenna element 6 to the wavelength of the center frequency of the FM broadcast band and _{λ M, 0.5 (λ M /4)×K~1.2(λ} M / 4) XK is preferred. When it is within this range, the sensitivity of the FM broadcast band is improved as compared to when it is outside this range.
[0017]
The interval between the substantially horizontal portion 8 and the lowermost heater wire 2a is set to 10 to 50 mm, particularly 15 to 30 mm so that the capacitive coupling is difficult in the medium wave broadcasting and the capacitive coupling is performed in the FM broadcasting band. It is preferable. The sensitivity of the FM broadcast band is improved by capacitive coupling. If it is 10 mm or more, it is difficult to capacitively couple in medium wave broadcasting, and if it is 50 mm or less, it becomes easy to capacitively couple in the FM broadcast band.
[0018]
The filter circuit 26 has a function of attenuating or blocking part or all of the frequency of at least one frequency band selected from the AM broadcast band and the long wave broadcast band. This attenuation or blocking function of the filter circuit 26 makes it difficult for vehicle noise from the vehicle body to flow to the defogger, thereby improving the S / N ratio.
[0019]
In the example shown in FIG. 1, a filter circuit 26 is connected between the bus bar 5 b and the anode of the DC power supply 22. That is, the filter circuit 26 is connected between the bus bar 5 b and the DC power supply 22. However, the present invention is not limited to this, and the filter circuit 26 may be connected between the bus bar 5a and the ground. Further, a filter circuit may be connected between the bus bar 5b and the DC power source and between the bus bar 5a and the ground.
[0020]
In the example shown in FIG. 1, the coil 12 is connected between the bus bar 5 b and the anode of the DC power supply 22, and the capacitor 11 is connected between the anode of the DC power supply 22 and the ground. That is, the filter circuit 26 includes the coil 12 and the capacitor 11. However, the present invention is not limited to this, and other circuit configurations may be used as long as the filter circuit 26 has a function of attenuating or blocking.
[0021]
In the example shown in FIG. 2, a part of the lower pattern of the third antenna element 6 is provided so as to substantially surround the upper half of the hole for the rear wiper so as to avoid the hole for the rear wiper. A part of the pattern of the highest heater line 2 is provided so as to substantially surround the lower half of the region 24 so as to avoid the region 24.
[0022]
When viewed as a pattern, the rear window glass antenna for automobiles in FIGS. 1 and 2 is viewed from the inside of the vehicle. However, the present invention is not limited to this, and the pattern of the rear window glass antenna for automobiles in FIGS.
[0023]
【Example】
EXAMPLES Examples will be described below, but the present invention is not limited to these examples, and various improvements and modifications are also included in the present invention as long as the gist of the present invention is not impaired.
[0024]
"Example 1 (Example)"
A rear window glass antenna for an automobile as shown in FIG. 1 was manufactured using an automobile rear window glass plate. A sixth antenna element 10 was provided. The dimensions of each part are as follows. The frequency-sensitivity characteristics of the LW broadcast band and the AM broadcast band are shown by solid lines in FIG. Further, the frequency-sensitivity characteristic of the FM broadcast band is shown by a solid line in FIG.
[0025]
The conductor length of the first antenna element 4 is 400 mm,
The conductor length of the second antenna element 15 is 630 mm,
The maximum horizontal width of the third antenna element 6 is 500 mm,
The maximum length of the third antenna element 6 is 95 mm;
The conductor length of the fourth antenna element 9 is 490 mm,
The conductor length of the substantially horizontal portion 8 of the fifth antenna element is 700 mm.
[0026]
Conductor length 25 mm of the substantially vertical portion 7 of the fifth antenna element;
The conductor length of the sixth antenna element 10 is 365 mm,
15 mm between the substantially horizontal portion 8 and the lowermost heater wire 2a,
The inductance value of the coil 12 is 100 μH,
The capacitance value of the capacitor 11 is 10.0 μF.
[0027]
"Example 2 (comparative example)"
A rear window glass antenna for an automobile as shown in FIG. 5 was manufactured using an automobile rear window glass plate. The inductance value of the choke coil 21 was 1.0 mH. The frequency-sensitivity characteristics of the LW broadcast band and the AM broadcast band are shown by broken lines in FIG. Further, the frequency-sensitivity characteristics of the FM broadcast band are shown by broken lines in FIG.
[0028]
【The invention's effect】
In the present invention, since the defogger is provided on the upper portion of the rear window glass plate, it is possible to prevent the upper portion of the rear window glass plate from being fogged and to improve the sensitivity. In addition, excellent sensitivity can be obtained as three combined antennas for the LW broadcast band, the AM broadcast band, and the FM broadcast band, and a choke coil having a large inductance value is unnecessary, which can contribute to cost reduction.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of an automotive rear window glass antenna of the present invention.
FIG. 2 is a configuration diagram of another embodiment of the rear window glass antenna for an automobile of the present invention.
FIG. 3 is a frequency-sensitivity characteristic diagram of the LW broadcast band and the AM broadcast band in Example 1 and Example 2.
4 is a frequency-sensitivity characteristic diagram of FM broadcast bands in Example 1 and Example 2. FIG.
FIG. 5 is a configuration diagram of a conventional rear window glass antenna for an automobile.
[Explanation of symbols]
1: rear window glass plate 2: heater wire 2a: bottom heater wire 2b: short-circuit wire 3: feeding point 4: first antenna element 5a, 5b: bus bar 6: third antenna element 7: fifth antenna Substantially vertical portion 8 of the element: Substantially horizontal portion of the fifth antenna element 9: Fourth antenna element 10: Sixth antenna element 15: Second antenna element 21: Choke coil 22: DC power supply

Claims (2)

An electric heating type defogger having a plurality of heater wires and a plurality of bus bars for supplying power to the heater wires is provided on the rear window glass plate of the automobile, and the lower margin of the rear window glass plate other than the area of the defogger The rear part for an automobile in which the antenna conductor and the feeding point of the antenna conductor are provided in the part, and the filter circuit is connected between the one bus bar and the DC power source and / or between the other bus bar and the ground. In the window glass antenna,
The filter circuit has a function of attenuating or blocking a frequency of at least one frequency band selected from a medium wave broadcast band and a long wave broadcast band,
The antenna conductor includes a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element,
Seen from the inside or outside of the car,
The feeding point is arranged near the right edge of the lower margin of the rear window glass plate,
The first antenna element is arranged along the lowermost heater line from the feed point so that it is difficult to be capacitively coupled to the lowermost heater line by medium wave broadcasting and is capacitively coupled to the FM broadcasting band. Being extended toward the left and right central direction of the rear window glass plate,
The second antenna element is extended substantially downward along the right edge of the rear window glass plate from the feeding point, and is bent and extended in the right and left central direction of the rear window glass plate in the vicinity of the lower right corner of the rear window glass plate. And
A loop-shaped third antenna element is connected to the tip of the second antenna element,
4. A rear window glass antenna for an automobile, wherein the fourth antenna element extends from the upper right part or the vicinity of the upper right part of the third antenna element toward the substantially right side. A fifth antenna element having a substantially horizontal portion is connected to the top of the third antenna element,
The substantially horizontal portion of the fifth antenna element is arranged at the position where the lower heater wire is capacitively coupled to the lower heater wire by medium wave broadcasting and is capacitively coupled by the FM broadcast band. The rear window glass antenna for automobiles according to claim 1, wherein the rear window glass antenna is extended toward the center of the left and right sides of the rear window glass plate.

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