JP2024062814A - Vehicle Antenna - Google Patents

Abstract

[Problem] To provide an in-vehicle antenna that can remove rain and snow adhering to its surface by passing a current through an electric heating resistor, and that can prevent the electric heating resistor itself from interfering with communications. [Solution] The in-vehicle antenna 11 is installed on the roof 100 of an automobile. The in-vehicle antenna 11 comprises an antenna body 51 that is a two-element patch array antenna, a heating wire 61 that is arranged below the antenna body 51 in the opposite direction to the radio wave radiation direction, a spacer 7, and a resin part 81 in which these are molded. When electricity is passed through the heating wire 61, heat generated by the heating wire 61 is conducted to the resin part 81, and the entire resin part 81 is heated. This makes it possible to melt snow 102 adhering to the upper surface of the in-vehicle antenna 11 and evaporate water. [Selected Figure] Figure 2

Description

The present invention relates to an on-board antenna that is installed on the roof of a vehicle.

With the launch of 5G services in 2020, automobiles will also need antennas compatible with 5G communications. 5G communications use high frequency bands, which means radio waves have a high degree of directivity and are less likely to bend around obstacles. For this reason, the ideal location for installing an in-vehicle antenna compatible with 5G communications is on the roof. However, when installed on the roof, rain and snow can accumulate on the antenna surface, which can significantly attenuate radio waves and cut off communications.

One example of a conventional vehicle-mounted antenna is disclosed in Patent Document 1. The antenna described in Patent Document 1 has a heating wire disposed on the outer surface of the antenna case, and when snow accumulates or the antenna is wet with rain, electricity is passed through the heating wire to generate heat, melting the snow and evaporating the water, thereby removing the rain and snow that adversely affect communications.

Japanese Patent Application Laid-Open No. 5-22024

In conventional antennas, rain and snow that have adhered to the antenna case can be removed by passing electricity through a heating wire, but the heating wire itself has a problem of adversely affecting the transmission and reception of radio waves. In particular, in the case of antennas that use technologies such as MIMO (Multiple-Input and Multiple-Output) technology and beamforming, which have come into widespread use in recent years, radio waves are not emitted only in a fixed direction, but are instead radiated by changing the direction of radiation to a specific direction, making it necessary to consider the effects of the heating wire more than ever before.

The present invention aims to provide an in-vehicle antenna that can remove rain and snow that has adhered to its surface by passing electricity through an electric heating resistor, and that can prevent the electric heating resistor itself from interfering with communications.

The present invention is an in-vehicle antenna that is installed on the roof of a vehicle, and is characterized in that it comprises an antenna body, an electric heating resistor arranged below the antenna body, and a resin part in which the antenna body and the electric heating resistor are molded, and when electricity is passed through the electric heating resistor, the heat generated by the electric heating resistor is conducted to the resin part.

According to the present invention, rain and snow adhering to the surface of a vehicle-mounted antenna can be removed by passing electricity through an electric heating resistor, and the electric heating resistor itself can be prevented from interfering with communications.

1 is a plan view showing a schematic diagram of an in-vehicle antenna according to a first embodiment of the present invention; 2 is a cross-sectional view taken along line AA of the vehicle-mounted antenna of FIG. 1 in a state where the antenna is installed on a vehicle. FIG. 2 is a bottom view showing the vehicle-mounted antenna of FIG. 1 . FIG. 11 is a bottom view showing a schematic diagram of an in-vehicle antenna according to a second embodiment of the present invention. FIG. 11 is a cross-sectional view of a vehicle-mounted antenna according to a third embodiment of the present invention in a state where the antenna is installed on a vehicle. FIG. 11 is a cross-sectional view of a vehicle-mounted antenna according to a fourth embodiment of the present invention in a state where the antenna is installed on a vehicle. FIG. 11 is a cross-sectional view of a vehicle-mounted antenna according to a fifth embodiment of the present invention in a state where the antenna is installed on a vehicle.

The "vehicle-mounted antenna" according to the first embodiment of the present invention will be described with reference to Figures 1 to 3.

The vehicle-mounted antenna 11 shown in Figures 1 to 3 is installed on the roof 100 of a vehicle. The vehicle-mounted antenna 11 in this example has an overall shape like a flat plate, and is embedded in a recess 101 formed in the roof 100.

The vehicle-mounted antenna 11 comprises an antenna body 51, which is a two-element patch array antenna, a heating wire (corresponding to a heating resistor) 61 arranged below the antenna body 51, a spacer 7, and a resin part 81 in which these are molded.

The antenna body 51 includes an antenna substrate 2 that is installed parallel to the roof 100, patch antenna elements 31 and 32 that are provided on the upper surface of the antenna substrate 2, and a ground plate 4 that is provided on the lower surface of the antenna substrate 2. The antenna substrate 2 is a dielectric material, and the antenna elements 31 and 32 and the ground plate 4 are conductors.

The heating wire 61 is disposed below the ground plate 4. The heating wire 61 is an electric wire made of a material with a high electrical resistance, such as a nichrome wire, and is disposed in a spiral shape around the antenna elements 31 and 32 as shown in FIG. 3. In addition, the heating wire 61 in this example is insulated and in contact with the ground plate 4, but contact with the ground plate 4 is not essential. The heating wire 61 may be disposed anywhere below the ground plate 4 and within the resin part 81, where it is unlikely to affect the antenna radio waves. The heating wire 61 is connected to a power source (not shown).

The spacer 7 is a member for positioning the antenna body 51 at a predetermined position within the resin part 81.

The resin part 81 is an insulating resin with high thermal conductivity, and in this example, epoxy resin is used. The resin part 81 molds the entire antenna body 51. The resin part 81 conducts heat generated by passing electricity through the heating wire 61 to the upper surface of the vehicle-mounted antenna 11 (the upper surface of the resin part 81). The resin part 81 also serves as an antenna case. As a result, the vehicle-mounted antenna 11 of this example does not require a case other than the resin part 81.

When electricity is applied to the heating wire 61 of this vehicle-mounted antenna 11, the heat generated by the heating wire 61 is transferred to the resin part 81, and the entire resin part 81 is heated. This makes it possible to melt snow 102 (Figure 2) that has adhered to the upper surface of the vehicle-mounted antenna 11 and evaporate water.

In addition, to save electricity, the presence or absence of rain or snow on the vehicle-mounted antenna 11 can be detected by a capacitance sensor or the like, and electricity to the heating wire 61 can be turned on/off when it is detected that radio waves from the antenna are being blocked.

As explained above, the vehicle-mounted antenna 11 is designed to minimize the influence of the heating wire 61 on the radio waves emitted from the antenna body 51 by arranging the heating wire 61 below (on the back side) of the antenna body 51, which is in the opposite direction to the radio wave radiation direction. However, when the heating wire 61 is arranged below the antenna body 51, it is difficult to transmit the heat of the heating wire 61 to the top surface of the antenna through the air. Therefore, in order to transmit the heat of the heating wire 61 to the top surface of the antenna, the antenna body 51 and the heating wire 61 are molded with a resin that has a higher thermal conductivity than air. Furthermore, this vehicle-mounted antenna 11 has a good appearance because the heating wire 61 is arranged below the antenna body 51 rather than along the outer surface of the case as in conventional products, and the heating wire 61 is not visible from the outside.

The "vehicle-mounted antenna" according to the second embodiment of the present invention will be described with reference to FIG. 4. In FIG. 4, the same components as those in the first embodiment are given the same reference numerals and will not be described.

The vehicle-mounted antenna 12 shown in FIG. 4 has the same configuration as the first embodiment, except for the arrangement of the heating wire (corresponding to the heating resistor) 62. The heating wire 61 in the first embodiment was arranged in a spiral shape with a circular course around the antenna elements 31 and 32, but the heating wire 62 in this example is arranged in a spiral shape with a course that bends in a straight line and at right angles around the antenna elements 31 and 32 below the ground plate 4.

Similar to the vehicle antenna 11 of the first embodiment, this type of vehicle antenna 12 can remove rain and snow that has adhered to the upper surface by passing electricity through the heating wire 62, and can prevent the heating wire 62 itself from interfering with communication.

In addition, in the present invention, the shape of the heating wires 61 and 62 is not limited to that shown in Figures 3 and 4, and the heating resistors may be arranged in any shape as long as they generate heat (however, it is essential that they are arranged below the antenna body and within the resin part).

The "vehicle antenna" according to the third embodiment of the present invention will be described with reference to FIG. 5. In FIG. 5, the same components as those in the first embodiment are given the same reference numerals and will not be described.

The vehicle-mounted antenna 13 shown in FIG. 5 includes the configuration of the vehicle-mounted antenna 11 of the first embodiment, as well as a resin case 91 that houses the vehicle-mounted antenna 11. It is preferable that the case 91 is as tightly attached as possible to the outer surface of the resin part 81 so that no air gap is formed between the case 91 and the resin part 81. This allows the heat generated by the heating wire 61 to be efficiently transferred to the top surface of the case 91 via the resin part 81.

In the first embodiment described above, the resin part 81 also serves as an antenna case, so that the vehicle-mounted antenna 11 does not require any case other than the resin part 81. However, some types of resin used as the "resin part" are poor in weather resistance and may deteriorate or discolor when installed on the roof 100, so a case 91 other than the resin part 81 may be provided as in this example. The resin used for the case 91 is preferably polycarbonate (PC), which has relatively good weather resistance, or an alloy of PC/ABS resin.

In this example, the antenna body 51, heating wire 61, and spacer 7 are placed inside the case 91, and then resin is injected into the case 91 and hardened to produce the vehicle-mounted antenna 13. Alternatively, an assembly (the vehicle-mounted antenna 11 of the first embodiment) may be produced in which the antenna body 51, heating wire 61, and spacer 7 are molded with a resin part 81, and the assembly may be inserted into the case 91.

Similar to the vehicle antenna 11 of the first embodiment, this type of vehicle antenna 13 can remove rain and snow that has adhered to the top surface of the case 91 by passing electricity through the heating wire 61, and can prevent the heating wire 61 itself from interfering with communication.

The "vehicle antenna" according to the fourth embodiment of the present invention will be described with reference to FIG. 6. In FIG. 6, the same components as those in the first embodiment are given the same reference numerals and will not be described.

The vehicle-mounted antenna 14 shown in FIG. 6 does not have the heating wire 61 described in the first embodiment, and instead has a heater pattern 64 as a heating resistor formed on the underside of the ground plate 4. In addition, although not shown, an insulating layer is interposed between the ground plate 4 and the heater pattern 64.

Similar to the vehicle antenna 11 of the first embodiment, this type of vehicle antenna 14 can remove rain and snow that has adhered to the upper surface by passing electricity through the heater pattern 64, and can also prevent the heating wire 62 itself from interfering with communications. In addition, by integrating the heater pattern 64 into the antenna body 51 as in this example, there is no need to prepare a separate heating wire, which leads to a reduction in manufacturing man-hours and the number of parts.

As such, the electric heating resistor of the present invention may be a heating wire or a heater pattern. It may also be a film heater that can withstand the heat generated during resin molding.

The "vehicle-mounted antenna" according to the fifth embodiment of the present invention will be described with reference to FIG. 7. In FIG. 7, the same components as those in the first embodiment are given the same reference numerals and will not be described.

The vehicle-mounted antenna 15 shown in FIG. 7 has a three-dimensional shape called a "shark fin antenna" and is installed on a flat portion of the roof 100 of the vehicle.

The vehicle-mounted antenna 15 is composed of antenna bodies 52 and 53, a heating wire 61 arranged below the antenna bodies 52 and 53, a spacer 7, a bottom plate 92, and a cover 93, and includes a case that houses the above-mentioned components, and a resin part 85 filled in the case.

The antenna body 52 includes an antenna substrate 21 that is installed parallel to the roof 100, patch antenna elements 31 and 32 that are provided on the upper surface of the antenna substrate 21, and a ground plate 45 that is provided on the lower surface of the antenna substrate 21. The antenna body 53 includes an antenna substrate 22 that is installed perpendicular to the roof 100. The ground plate 45 is formed to be larger than the antenna substrate 21, and the antenna substrate 22 is disposed on the ground plate 45 so as not to overlap with the antenna substrate 21.

The heating wire 61 is placed directly below the antenna board 21 and the ground plate 45, but not directly below the antenna board 22. In other words, the heating wire 61 is placed directly below the antenna board 21 and the ground plate 45, which is in the opposite direction to the radio wave radiation direction of the antenna body 52 and does not affect the radio waves of the antenna body 53.

The bottom plate 92 is formed in a plate shape and is placed on the roof 100. The cover 93 is made of resin and is formed in a hollow shark fin shape that opens downward. The bottom plate 92 and the cover 93 are assembled together, and the bottom plate 92 closes the lower opening of the cover 93.

The resin part 85 is filled inside the case and molds the entire antenna body 52, 53. The resin part 85 conducts the heat generated by passing electricity through the heating wire 61 to the surface of the cover 93.

When electricity is applied to the heating wire 61 of this type of vehicle-mounted antenna 15, the heat generated by the heating wire 61 is transferred to the resin part 85, and the entire resin part 85 is heated. This makes it possible to melt snow 102 adhering to the surface of the cover 93 and evaporate water. In addition, the heating wire 61 itself can be prevented from interfering with communication of the vehicle-mounted antenna 15.

The above-described embodiment merely shows a typical form of the present invention, and the present invention is not limited to this embodiment. In other words, the present invention can be implemented with various modifications within the scope of the gist of the present invention. As long as the configuration of the present invention is still included in such modifications, it is of course included in the scope of the present invention.

2, 21 Antenna substrate 4, 45 Ground plate 11, 12, 13, 14, 15 Vehicle-mounted antenna 31, 32 Antenna element 51, 52, 53 Antenna body 61, 62 Heating wire (heating resistor)
64 Heater pattern (electrical resistor)
81, 85 Resin part 91 Case 92 Bottom plate (case)
93 Cover (case)
100 Roof

Claims (4)

An on-vehicle antenna installed on the roof of a vehicle,
The antenna device includes an antenna body, a thermal resistor disposed below the antenna body, and a resin portion in which the antenna body and the thermal resistor are molded,
When a current is applied to the electric heating resistor, heat generated in the electric heating resistor is conducted to the resin portion. the antenna body includes an antenna substrate disposed parallel to the roof, a patch antenna element provided on an upper surface of the antenna substrate, and a ground plate provided on a lower surface of the antenna substrate;
The vehicle-mounted antenna according to claim 1 , wherein the electric heating resistor is disposed below the ground plate. 3. The vehicle-mounted antenna according to claim 2, wherein a heater pattern serving as the electric heating resistor is formed on a lower surface of the ground plate. a resin case that houses the antenna body and the electric heating resistor;
The resin portion is filled in the case,
4. The vehicle-mounted antenna according to claim 1, wherein heat generated in the electric heating resistor is conducted to the case via the resin portion.

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