阅读说明：本技术 车载雷达装置用雷达罩 (Radar cover for vehicle-mounted radar device ) 是由 古林宏之 山本真平 高草木诚 池增竜帆 于 2020-02-07 设计创作，主要内容包括：车载雷达装置用雷达罩(1)具备以在电磁波透过性的基材的面方向上分离且并列的方式布线的加热器线(3),在基材的电磁波透过区域(R)并列的加热器线(3)的线间距d被设定为车载雷达装置的雷达的电磁波的波长的0.2～2.5倍,并且在基材的电磁波透过区域(R)并列的加热器线(3)的面占有率被设定为超过10％且35％以下。提供能够得到作为雷达罩所需的电磁波的透过性并且能够进行基于较高的加热器性能的良好的融雪的车载雷达装置用雷达罩。(A radar cover (1) for an in-vehicle radar device is provided with heater wires (3) that are wired in a manner that they are separated and arranged in parallel in the surface direction of a base material that is permeable to electromagnetic waves, wherein the pitch d between the heater wires (3) arranged in parallel in an electromagnetic wave permeable region (R) of the base material is set to be 0.2 to 2.5 times the wavelength of the electromagnetic waves of a radar of the in-vehicle radar device, and the surface occupancy of the heater wires (3) arranged in parallel in the electromagnetic wave permeable region (R) of the base material is set to be more than 10% and 35% or less. Provided is a radar cover for a vehicle-mounted radar device, which can obtain the permeability of electromagnetic waves required for the radar cover and can perform good snow melting based on high heater performance.)

1. A radar cover for a vehicle-mounted radar apparatus, characterized in that,

comprises heater wires arranged in parallel and separated in the surface direction of the substrate having electromagnetic wave permeability,

the pitch of the heater lines arranged in the electromagnetic wave transmission region of the base material is set to be 0.2 to 2.5 times the wavelength of the electromagnetic wave of the radar of the vehicle-mounted radar device, and

the area occupancy of the heater lines arranged in the electromagnetic wave transmission region of the substrate is set to be more than 10% and 35% or less.

2. The radome for the vehicle-mounted radar device according to claim 1,

the pitch of the heater lines arranged in the electromagnetic wave transmission region of the base material is set to be 1.6 to 2.0 times the wavelength of the electromagnetic wave of the radar of the vehicle-mounted radar device, and

the area occupancy of the heater lines arranged in the electromagnetic wave transmission region of the substrate is set to be more than 10% and 25% or less.

3. The radome for the vehicle-mounted radar device according to claim 2,

the area occupancy of the heater lines arranged in the electromagnetic wave transmission region of the substrate is set to be more than 10% and 20% or less.

4. The radome for the vehicle-mounted radar device according to claim 2,

the pitch of the heater lines arranged in the electromagnetic wave transmission region of the base material is set to be 1.7 to 2.0 times the wavelength of the electromagnetic wave of the radar of the vehicle-mounted radar device.

5. The radome for the vehicle-mounted radar device according to claim 1,

the pitch of the heater lines arranged in the electromagnetic wave transmission region of the base material is set to be 1.5 to 2.3 times the wavelength of the electromagnetic wave of the radar of the vehicle-mounted radar device, and

the area occupancy of the heater lines arranged in the electromagnetic wave transmission region of the substrate is set to be more than 10% and 20% or less.

6. The radome for the vehicle-mounted radar device according to claim 1,

the area occupancy of the heater wires arranged in the electromagnetic wave transmission region of the substrate is set to be more than 10% and 15% or less.

7. The radome for the vehicle-mounted radar device according to any one of claims 1 to 6,

directions of currents flowing in the heater wires of adjacent wirings are substantially antiparallel to each other.

Technical Field

The present invention relates to a radar cover for a vehicle-mounted radar device provided on a front side of the vehicle-mounted radar device, and more particularly to a radar cover for a vehicle-mounted radar device having a snow melting function.

Background

Conventionally, there has been known a radome that exhibits a snow melting function while ensuring the necessary permeability of electromagnetic waves as a radome for an in-vehicle radar device, and patent documents 1 and 2 are known as such radomes. The radome of patent documents 1 and 2 has the following structure: the heater lines are wired in a separated and parallel manner on the surface of the base material provided so as to be substantially orthogonal to the electromagnetic wave irradiation direction of the vehicle-mounted radar device.

In the radar covers of patent documents 1 and 2, in order to ensure the permeability of electromagnetic waves required for the radar cover for an in-vehicle radar device, the allowable value of attenuation of electromagnetic waves is set to 2.5dB by adjusting the pitch of the straight portions of the heater wire or the like so that the area ratio of the heater wire is 10% or less (see paragraphs [0052] and [0070] of patent document 1 and paragraphs [0048] and [0077] of patent document 2).

Documents of the prior art

Patent document 1: japanese laid-open patent publication No. 2018-66705

Patent document 2: japanese laid-open patent publication No. 2018-66706

Disclosure of Invention

Problems to be solved by the invention

However, patent documents 1 and 2 show that the area ratio of the heater wire is set to 10% or less in order to achieve a desired allowable value of the attenuation amount of the electromagnetic wave, but it is not clear how to set the wire pitch of the heater wire. In addition, when the area ratio of the heater wire is set to 10% or less, the snow melting function may be degraded.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a radar cover for an in-vehicle radar device, which can obtain permeability of electromagnetic waves for radar required as a radar cover and can melt snow well with high heater performance.

Means for solving the problems

The radar cover for an in-vehicle radar device of the present invention includes heater lines wired in a manner separated and arranged in parallel in a surface direction of a base material having electromagnetic wave permeability, wherein a line pitch of the heater lines arranged in parallel in an electromagnetic wave transmission region of the base material is set to be 0.2 to 2.5 times a wavelength of an electromagnetic wave of a radar of the in-vehicle radar device, and a surface occupancy rate of the heater lines arranged in parallel in the electromagnetic wave transmission region of the base material is set to be more than 10% and 35% or less.

This makes it possible to obtain the transparency of electromagnetic waves required for a radome and to melt snow with high heater performance by the heater wire having a large area occupancy. Further, the heater wires arranged at a predetermined pitch make it possible to melt snow with good balance over the entire electromagnetic wave transmission region of the radar cover. In addition, since snow can be melted in a well-balanced manner over the entire electromagnetic wave transmission region, the electromagnetic wave transmission performance can be stabilized over the entire electromagnetic wave transmission region, and excellent electromagnetic wave transmission performance can be obtained from this viewpoint as well.

The radar cover for an in-vehicle radar device according to the present invention is characterized in that the pitch of the heater lines arranged in the electromagnetic wave transmission region of the base material is set to be 1.6 to 2.0 times the wavelength of the electromagnetic wave of the radar of the in-vehicle radar device, and the area occupancy of the heater lines arranged in the electromagnetic wave transmission region of the base material is set to be more than 10% and 25% or less.

This makes it possible to perform good snow melting with high heater performance and to exhibit more excellent electromagnetic wave transmission performance.

The radar cover for an in-vehicle radar device according to the present invention is characterized in that a surface occupancy of the heater wires arranged in parallel in the electromagnetic wave transmission region of the base material is set to be more than 10% and 20% or less.

Thus, snow can be melted well with high heater performance, and the allowable value of the attenuation amount of the electromagnetic wave can be 2.0dB or a corresponding allowable value, and more excellent transmission performance of the electromagnetic wave can be exhibited.

The radar cover for an in-vehicle radar device according to the present invention is characterized in that a pitch of the heater lines arranged in parallel in the electromagnetic wave transmission region of the base material is set to be 1.7 to 2.0 times a wavelength of an electromagnetic wave of a radar of the in-vehicle radar device.

Thus, snow can be melted well and reliably with higher heater performance, and the allowable value of the attenuation amount of the electromagnetic wave can be 2.0dB or a corresponding allowable value, and more excellent transmission performance of the electromagnetic wave can be exhibited.

The radar cover for an in-vehicle radar device according to the present invention is characterized in that the pitch of the heater wires arranged in parallel in the electromagnetic wave transmission region of the base material is set to be 1.5 to 2.3 times the wavelength of the electromagnetic wave of the radar of the in-vehicle radar device, and the area occupancy of the heater wires arranged in parallel in the electromagnetic wave transmission region of the base material is set to be more than 10% and 20% or less.

This makes it possible to melt snow satisfactorily with high heater performance, and to achieve an allowable value of attenuation of electromagnetic waves of 2.5dB or a value corresponding thereto, thereby exhibiting excellent transmission performance of electromagnetic waves.

The radar cover for an in-vehicle radar device according to the present invention is characterized in that a surface occupancy of the heater wires arranged in parallel in the electromagnetic wave transmission region of the base material is set to be more than 10% and 15% or less.

Thus, snow can be melted well with high heater performance, and the allowable value of the attenuation amount of the electromagnetic wave can be 2.5dB or a corresponding allowable value, and excellent transmission performance of the electromagnetic wave can be exhibited. In addition, the degree of freedom in setting the pitch of the heater wire and the degree of freedom in design can be increased according to the wavelength of the radar used.

In the radar cover for an in-vehicle radar device according to the present invention, the directions of currents flowing through the heater wires that are wired adjacent to each other are substantially antiparallel to each other.

Thus, by making the directions of the currents flowing in the adjacent heater wires substantially antiparallel to each other, the electromagnetic waves radiated from the adjacent heater wires can be made in opposite phases, the electromagnetic radiation from the heater wires can be eliminated, and more excellent electromagnetic wave transmission performance can be obtained. In particular, by making the directions of currents flowing through the heater lines of adjacent wirings substantially antiparallel to each other, very excellent electromagnetic wave transmission performance can be exhibited as a whole.

Effects of the invention

According to the radar cover for an in-vehicle radar device of the present invention, it is possible to obtain the permeability of electromagnetic waves required for the radar cover and perform excellent snow melting due to high heater performance.

Drawings

Fig. 1 is a front view of a radar cover for a vehicle-mounted radar device according to an embodiment of the present invention.

Fig. 2 is a partially enlarged vertical sectional view illustrating a radome for a vehicle-mounted radar device according to an embodiment.

Fig. 3 (a) is a rear view of a base material and a heater wire constituting an example of a radar cover for an in-vehicle radar device, and (b) is a cross-sectional view thereof taken along line a-a.

Fig. 4 is an explanatory diagram illustrating a line pitch and a line width of the heater line.

Fig. 5 is a schematic view of a measuring apparatus for measuring the relationship among the surface occupancy of the heater wire, the wire pitch of the heater wire, and the electromagnetic wave transmittance.

FIG. 6 is a graph showing an experimental example of the relationship between the surface occupancy of the heater wire at 76.5GHz, the wire pitch (unit: mm) of the heater wire, and the electromagnetic wave transmittance.

Fig. 7 is a graph showing an experimental example of the relationship between the surface occupancy of the heater wire, the wire pitch of the heater wire (expressed as a multiple of the wavelength of the electromagnetic wave applied to the radar), and the transmittance of the electromagnetic wave.

Detailed Description

[ Radar cover for vehicle-mounted radar device of embodiment ]

As shown in fig. 1 and 2, a radar cover 1 for an in-vehicle radar device according to an embodiment of the present invention includes a base body 2 that is transparent to electromagnetic waves, and heater wires 3 that are wired so as to be separated and arranged in parallel in a surface direction of the base body 2, and the heater wires 3 are provided on a rear surface side of the base body 2. The base body 2 in the example of the figure is an oval shape when viewed from the front, and the heater wires 3 are wired so as to follow the oval surface. In fig. 1, 10 is a mark portion, which is a mark portion of a character or the like of a mark such as a logo, and in the illustrated example, is a character-shaped mark portion 10.

The base body 2 is composed of a transparent front base material 21 and a transparent rear base material 22, and the front base material 21 and the rear base material 22 are insulating and have electromagnetic wave permeability. For example, if the front substrate 21 and the rear substrate 22 are formed of the same material, and the refractive indices n defined based on the complex dielectric constant are matched with each other, or the refractive indices n are substantially the same or close to each other, it is preferable from the viewpoint of improving the transmission performance of electromagnetic waves. As the numerical range of the refractive indexes close to each other of the front substrate 21 and the rear substrate 22, it is preferable that the difference between the refractive indexes of the front substrate 21 and the rear substrate 22 is in the range of 0 to 10%.

The refractive index n here is defined as a quantity of equation 1 by a real relative permittivity part ∈ r' and an imaginary relative permittivity part ∈ r ″. From the viewpoint of permeability, the magnitude of the dielectric loss tangent (loss tangent) tan δ defined by the ratio of the imaginary part to the real part in the applied frequency as equation 2 is preferably 0.1 or less. The magnitude of the real part of the relative permittivity is preferably 3 or less. By setting the magnitudes of the dielectric loss tangent and the real non-permittivity part to values equal to or less than these values, it is possible to reliably achieve reduction in reflectance and internal loss required for the radome.

[ mathematical formula 1]

[ mathematical formula 2]

The front substrate 21 and the rear substrate 22 may be made of any suitable material within the scope of the present invention, such as synthetic resin, glass, or ceramic, but are preferably made of insulating synthetic resin. In order to ensure good visibility, the transparent front base material 21 is preferably a colorless material or a colored material having a visible light transmittance of 50% or more.

The material when the front substrate 21 is made of an insulating transparent synthetic resin is suitable insofar AS it can be used, and for example, one or two or more of acrylic resin such AS polymethyl methacrylate (PMMA), Polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), Polyethylene (PE), polypropylene (PP), acrylonitrile-styrene copolymer (AS), Polystyrene (PS), cycloolefin polymer (COP), and the like may be used alone or in combination, or additives may be contained.

The material when the rear substrate 22 is an insulating synthetic resin is suitable insofar as it can be used, and for example, one or two or more of acrylic resin such as polymethyl methacrylate (PMMA), Polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene-acrylate copolymer (ASA), acrylonitrile-vinyl propyl rubber-styrene copolymer (AES), and the like may be used alone or in combination, or additives may be contained.

A concave portion 212 is formed at a position corresponding to the mark portion 10 on the back surface 211 of the front base 21, a convex portion 222 is formed at a position corresponding to the mark portion 10 on the front surface 221 of the rear base 22, and the front base 21 and the rear base 22 are stacked so that the concave portion 212 and the convex portion 222 formed at the corresponding positions are fitted to each other. The electromagnetic wave-permeable metal layer 23 is closely provided over the entire surface of the convex portion 222 and the flat portion 223 around the convex portion 222 on the surface 221 of the rear substrate 22.

The electromagnetic wave-permeable metal layer 23 is formed of a discontinuous metal layer having electromagnetic wave permeability and metallic luster, has glitter and integral visibility, and is formed on the surface 221 of the rear base material 22 by electroless plating, vapor deposition, sputtering, or the like. When the electromagnetic wave-permeable metal layer 23 is a discontinuous metal layer having glittering properties and integral visibility, it may be made of, for example, nickel or a nickel alloy, chromium or a chromium alloy, cobalt or a cobalt alloy, tin or a tin alloy, copper or a copper alloy, silver or a silver alloy, palladium or a palladium alloy, platinum or a platinum alloy, rhodium or a rhodium alloy, gold or a gold alloy, or the like.

The electromagnetic wave-permeable metal layer 23 may be provided as an appropriate electromagnetic wave-permeable metal layer in addition to a discontinuous metal layer having electromagnetic wave permeability and having visibility integrated with metallic luster, and may be, for example, a semiconductor layer of silicon or germanium formed by vapor deposition, sputtering, or the like, or an alloy layer of the semiconductor and a bright metal such as a metal having a visible light reflectance of 50% or more (for example, gold, silver, copper, aluminum, platinum, palladium, iron, nickel, chromium), or the like. Further, a base layer such as a transparent base layer for forming a modified surface on which an electroless plating layer is easily formed, for example, a base layer such as a base layer may be provided between the surface 221 of the rear substrate 22 and the electromagnetic wave-transmissive metal layer 23 as necessary.

The colored layer 24 as a decorative layer laminated on the front surface side of the electromagnetic wave-permeable metal layer 23 is provided in close contact with the flat surface portion 223 around the convex portion 222 of the rear substrate 22, in other words, the colored layer 24 is provided in a region corresponding to the flat surface portion 213 around the concave portion 212 of the rear surface 211 of the front substrate 21. The colored layer 24 has electromagnetic wave permeability and is formed by being fixed to the surface of the electromagnetic wave permeable metal layer 23 by printing, coating using a coating mask, or the like.

The front substrate 21 is fixedly provided on the front side of the rear substrate 22 on which the electromagnetic wave transmissive metal layer 23 and the colored layer 24 are formed. The front base 21 can be fixed by, for example, a structure in which the back surface 211 of the front base 21 and the electromagnetic wave transmissive metal layer 23 and the colored layer 24 formed on the rear base 22 are bonded to each other via an adhesive layer of an adhesive, or a structure in which the back surface 211 of the front base 21 and the electromagnetic wave transmissive metal layer 23 and the colored layer 24 formed on the rear base 22 are welded to each other by pouring molten resin to be the front base 21 into the front side of the rear base 22 on which the electromagnetic wave transmissive metal layer 23 and the colored layer 24 are formed by injection molding.

In addition, instead of the above configuration, the following configuration may be adopted: the colored layer 24 is fixedly formed on the flat surface portion 213 around the concave portion 212 on the back surface 211 of the front base 21 by printing, painting using a paint mask, or the like, and the electromagnetic wave-permeable metal layer 23 formed on the rear base 22, the colored layer 24 of the front base 21, and the concave portion 212 of the front base 21 are fixed by bonding or the like via an adhesive layer of an adhesive.

The heater wire 3 is provided on the back side of the base body 2 formed of the transparent front base material 21 and the transparent rear base material 22, and is disposed on the rear side of the marking portion 10. The heater wires 3 are wired along the rear surface 224 of the rear substrate 22 corresponding to the substrate having electromagnetic wave permeability, and are wired so as to be separated and arranged in parallel in the surface direction of the rear surface 224 of the rear substrate 22. The heater wire 3 may be formed by printing, vapor deposition, sputtering, plating, wire bonding, or the like on the back surface 224 of the rear substrate 22 using a transparent conductive film such as an ITO film, a nichrome wire, an iron chromium wire, a carbon fiber, or an appropriate heating wire that can be used.

The heater wires 3 are provided such that the wire pitch d of the heater wires 3 arranged in parallel in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material is set to 0.2 to 2.5 times the wavelength of the electromagnetic wave of the radar of the in-vehicle radar device 100 (the wavelength of the radar electromagnetic wave that performs the radar function of the in-vehicle radar device 100, the wavelength in the air) or the wavelength in the millimeter wave of the air, and the surface occupancy of the heater wires 3 arranged in parallel in the electromagnetic wave transmission region R is set to more than 10% and 35% or less. Here, the line pitch d of the heater lines 3 is a distance between center positions in the width direction of the adjacent heater lines 3. The area occupancy of the heater line is a value calculated by (line width w of the heater line/line pitch d of the heater line) × 100 (see fig. 4).

Preferably, the heater wires 3 are provided such that the pitch d of the heater wires 3 arranged in parallel in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material is set to be 1.6 to 2.0 times the wavelength (wavelength in air) of the electromagnetic wave of the radar of the in-vehicle radar device 100, and the area occupancy of the heater wires 3 arranged in parallel in the electromagnetic wave transmission region R is set to be more than 10% and 25% or less. In the preferred configuration, the heater wire 3 is more preferably provided so that the area occupancy of the heater wires 3 arranged in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material is set to be more than 10% and 20% or less. In the preferred configuration, the heater wires 3 arranged in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material are more preferably arranged so that the pitch d between the heater wires is set to 1.7 to 2.0 times the wavelength of the electromagnetic wave of the radar (the wavelength in the air) of the in-vehicle radar device 100.

Further, the heater wire 3 preferably has the following structure: the heater wires 3 are arranged so that the pitch d of the heater wires 3 arranged in parallel in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material is set to be 1.5 to 2.3 times the wavelength (wavelength in air) of the electromagnetic wave of the radar of the in-vehicle radar device 100, and the heater wires 3 arranged in parallel in the electromagnetic wave transmission region R are set so that the area occupancy rate exceeds 10% and is 20% or less.

Further, the heater wire 3 preferably has the following structure: the heater wires 3 are arranged so that the area occupancy of the heater wires 3 arranged in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material is set to be more than 10% and 15% or less.

Both ends of the heater wire 3 of the present embodiment are electrically and mechanically fixed to the connector 4, and power is supplied to the heater wire 3 through the connector 4 to generate heat in the heater wire 3. The heater lines 3 extending from the connectors 4 are continuously extended so as to be meandering in the surface direction of the back surface 224 of the rear substrate 22, and the directions of currents flowing through the heater lines 3 of adjacent lines are set to be substantially antiparallel or antiparallel to each other.

The back surface member 6 is disposed at a position behind the heater wire 3 and is fixedly provided on the base 2. The back material 6 is insulating and electromagnetic wave-transmitting, and is formed in the same shape as the rear substrate 22. The back surface material 6 is preferably formed of the same material as the rear substrate 22, for example, from the viewpoint of improving the transmission performance of electromagnetic waves, if it is formed of a material having a refractive index defined based on the complex dielectric constant which matches the refractive index of the front substrate 21 and the rear substrate 22 or which is substantially the same as or close to the refractive index.

In this example, the adhesive layer 5 is provided so as to fill the part of the back surface 224 of the rear substrate 22 where the heater wires 3 are not arranged, and the back surface material 6 is bonded to the rear substrate 22 by the adhesive layer 5 using an adhesive. The adhesive layer 5 can be formed of an appropriate material having insulating properties and electromagnetic wave permeability, and can be formed of, for example, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, or the like. The heater line 3 may be formed on the front surface 61 of the back surface material 6 by printing or the like to be wired.

The radome 1 for an in-vehicle radar device is disposed in front of the in-vehicle radar device 100 and is attached to the vehicle. The radar cover 1 for an in-vehicle radar device illustrated in the drawings is a marker-shaped radar cover, but the radar cover for an in-vehicle radar device according to the present invention may be configured by an appropriate vehicle-mounted component such as a bumper.

According to the radar cover 1 for an in-vehicle radar device of the present embodiment, the transparency of electromagnetic waves required for a radar cover can be obtained, and snow can be melted well with high heater performance by the heater wire 3 having a large area occupancy ratio. Further, the heater wires 3 arranged at the predetermined wire pitch d allow snow to be melted with good balance over the entire electromagnetic wave transmission region R of the radar cover. In addition, since the entire electromagnetic wave transmission region R can be snowmelt with good balance, the transmission performance of electromagnetic waves can be stabilized in the entire electromagnetic wave transmission region R, and excellent electromagnetic wave transmission performance can be obtained from this viewpoint as well.

In addition, in the case of adopting a preferable configuration in which the pitch d of the heater wires 3 arranged in the electromagnetic wave transmission region R is set to be 1.6 to 2.0 times the wavelength of the electromagnetic wave of the radar of the in-vehicle radar device 100, and the area occupancy of the heater wires 3 arranged in the electromagnetic wave transmission region R is set to exceed 10% and to be 25% or less, it is possible to perform good snow melting with high heater performance and to exhibit more excellent electromagnetic wave transmission performance. In particular, in the preferred configuration, when the area occupancy of the heater wires 3 arranged in the electromagnetic wave transmission region R is set to exceed 10% and 20% or less, snow can be melted satisfactorily with high heater performance, and the allowable value of the attenuation amount of the electromagnetic wave can be 2.0dB or a value corresponding thereto, and more excellent transmission performance of the electromagnetic wave can be exhibited. In the preferred configuration, when the pitch d of the heater wires 3 arranged in the electromagnetic wave transmission region R is set to be 1.7 to 2.0 times the wavelength of the electromagnetic wave of the radar of the in-vehicle radar device 100, snow can be melted with high heater performance and high reliability, and the allowable value of the attenuation amount of the electromagnetic wave can be 2.0dB or a corresponding allowable value, and excellent electromagnetic wave transmission performance can be exhibited.

In addition, in the case of adopting a preferable configuration in which the pitch d of the heater wires 3 arranged in the electromagnetic wave transmission region R is set to be 1.5 to 2.3 times the wavelength of the electromagnetic wave of the radar of the in-vehicle radar device 100, and the area occupancy of the heater wires 3 arranged in the electromagnetic wave transmission region R is set to exceed 10% and 20% or less, it is possible to perform good snow melting with high heater performance, and it is possible to reach 2.5dB or a corresponding allowable value as an allowable value of the attenuation amount of the electromagnetic wave, and it is possible to exhibit excellent electromagnetic wave transmission performance.

In addition, in the case of adopting a preferable configuration in which the area occupancy of the heater wires 3 arranged in the electromagnetic wave transmission region R of the base body 2 or the rear base material 22 corresponding to the base material is set to exceed 10% and 15% or less, it is possible to perform good snow melting with high heater performance, and it is possible to achieve a permissible value of attenuation amount of electromagnetic wave of 2.5dB or a permissible value corresponding thereto, and it is possible to exhibit excellent transmission performance of electromagnetic wave, and it is possible to improve the degree of freedom in setting the wire pitch d of the heater wires 3 and the degree of freedom in design.

Further, by making the directions of the currents flowing through the adjacent heater wires 3 substantially antiparallel or antiparallel to each other, the electromagnetic waves radiated from the adjacent heater wires 3, 3 can be made in opposite phases, the electromagnetic radiation from the heater wires 3 can be eliminated, and more excellent electromagnetic wave transmission performance can be obtained. In particular, by making the directions of the currents flowing through the heater wires 3 of the adjacent wires substantially antiparallel or antiparallel to each other, it is possible to exhibit very excellent electromagnetic wave transmission performance as a whole.

[ Experimental example relating to the relationship between the area occupancy of the heater wire and the wire pitch and electromagnetic wave transmittance of the heater wire ]

As shown in fig. 3 and 5, a synthetic resin sheet 71 formed of AES (acrylonitrile-ethylene-propyl rubber-styrene copolymer) having a relative dielectric constant of 2.665 and a dielectric loss tangent of 0.01 and having a thickness of 5.993mm was used as a synthetic resin sheet corresponding to a base material of the electromagnetic wave permeability of the radar cover for an in-vehicle radar apparatus of the present invention, and a heater wire 72 having an area resistance of 0.2 Ω/□ was folded back and wired in a meandering manner on the synthetic resin sheet 71. The heater lines 72 are wired in the electromagnetic wave transmission region R' so that the straight portions of the heater lines 72 are arranged at a constant interval, and an experiment is performed while changing the surface occupancy of the heater lines 72 and the line pitch d of the heater lines 72 (see fig. 4).

The experimental determination was carried out using the Radar Alignment System (RAS) model SM5899 by KEYCOM. Fig. 5 schematically shows an electromagnetic wave transmission unit 73, a reception unit 74, and an evaluation device 75 of this system. The transmitted electromagnetic wave is 76.5GHz, and EW is the propagation direction of the electromagnetic wave. The thickness 5.993mm of the synthetic resin plate 71 here corresponds to exactly 5 times the half wavelength of the synthetic resin plate 71 at 76.5 GHz.

Then, the electromagnetic wave is irradiated from the heater wire 72 side of the synthetic resin plate 71, and the wire pitch d of the heater wire 72 is changed for each of 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40% of the surface occupancy of the heater wire 72 in the electromagnetic wave transmission region R', and the transmittance of the electromagnetic wave is measured. No current flows through the heater wire 72 at each measurement. The measurement results are shown in fig. 6 and 7.

From the viewpoint of ensuring the permeability of electromagnetic waves required for a radome and ensuring high heater performance that enables good snow melting, it is preferable to set the line pitch d of the heater lines 72 arranged in the electromagnetic wave transmission region R 'of the synthetic resin plate 71 corresponding to the base material to 0.2 to 2.5 times, preferably 1.6 to 2.0 times, more preferably 1.7 to 2.0 times, the wavelength (wavelength in air) of the electromagnetic wave transmission unit 73 corresponding to the radar of the vehicle-mounted radar device, and it is preferable to set the area occupancy of the heater lines 72 arranged in the electromagnetic wave transmission region R' to more than 10% and 35% or less, preferably more than 10% and 25% or less, more preferably more than 10% and 20% or less. Thus, for example, when applied to an 76/77GHz band radar, the wavelength of electromagnetic waves in air at 76.0GHz is 3.94mm, and the wavelength of electromagnetic waves in air at 76.0GHz is 3.89mm, so that the pitch d of the heater wires 72 is set to 0.78 to 9.73mm, preferably 6.30 to 7.78mm, more preferably 6.69 to 7.78mm, and the area occupancy of the heater wires 72 arranged in the electromagnetic wave transmission region R' is set to more than 10% and 35% or less, preferably more than 10% and 25% or less, and more preferably more than 10% and 20% or less. Fig. 6 is an example of a case of 76.5GHz (the wavelength of electromagnetic waves in air is 3.92 mm).

Further, even if the line pitch d of the heater wires 72 arranged in the electromagnetic wave transmission region R 'of the synthetic resin sheet 71 corresponding to the base material is set to be 1.5 to 2.3 times the wavelength (wavelength in the air) of the electromagnetic wave transmission part 73 corresponding to the radar of the vehicle-mounted radar device, and the surface occupancy of the heater wires 72 arranged in the electromagnetic wave transmission region R' is set to exceed 10% and 20% or less, it is possible to perform satisfactory snow melting with high heater performance, and it is preferable that the allowable value of the attenuation amount of the electromagnetic wave is 2.5dB or a corresponding allowable value.

Even if the structure is adopted in which the area occupancy of the heater wires 72 arranged in parallel in the electromagnetic wave transmission region R' corresponding to the base synthetic resin plate 71 is set to exceed 10% and 20% or less, it is possible to perform satisfactory snow melting with high heater performance, and the allowable value of the attenuation amount of the electromagnetic wave can be 2.5dB or a corresponding allowable value, and it is also possible to further improve the degree of freedom in design, which is preferable.

[ the scope of the invention disclosed in this specification ]

The invention disclosed in the present specification includes, in addition to the inventions and embodiments listed as inventions, contents specified by changing the contents of these portions to other contents disclosed in the present specification, contents specified by adding other contents disclosed in the present specification to these contents, or contents specified by deleting the contents of these portions to the extent that the effects of the portions can be obtained, and generalizing them in a general sense, within a range where the invention can be applied. The invention disclosed in the present specification includes the following modifications and additional descriptions.

For example, the radome for a vehicle-mounted radar device according to the present invention is preferably configured such that the directions of currents flowing through the heater lines of adjacent wiring lines are substantially antiparallel or antiparallel to each other, but may include a configuration in which the directions of currents flowing through the heater lines of adjacent wiring lines are not substantially antiparallel or antiparallel to each other. The electromagnetic wave-permeable substrate of the radar cover for an in-vehicle radar device according to the present invention is not limited to the rear substrate 22 in the case where the front substrate 21 and the rear substrate 22 are provided in the above-described embodiment, and is suitable within the scope of the present invention, and includes a suitable substrate in which the heater wire is wired in the in-plane direction.

The electromagnetic wave of the radar targeted by the radar cover for an in-vehicle radar device of the present invention is suitable in the applicable range, and may be applied to electromagnetic waves for other radars in addition to the 24/26GHz band, 76/77GHz band, 77/81GHz band, and the like that are put into practical use as an in-vehicle radar, and the present invention may be applied by setting the arrangement pattern of the heater wire in accordance with the suitable frequency. In addition, when a radar of a shorter wavelength is put to practical use, the present invention can be applied by setting the arrangement pattern of the heater lines in the same manner.

Industrial applicability

The present invention can be used for a radar cover for a vehicle-mounted radar device.

Description of the reference numerals

1 … vehicle-mounted radar apparatus radar cover 2 … base 21 … front base 211 … back surface 212 … recess 213 … plane 22 … back base 221 … surface 222 … convex 223 … plane 224 … back surface 23 … electromagnetic wave transmissive metal layer 24 … colored layer 3 … heater line 4 … connector 5 … adhesive layer 6 … back surface 61 … surface 10 … mark sign 100 … vehicle-mounted radar apparatus …' … electromagnetic wave transmissive region d … heater line width 71 … synthetic resin plate 72 heater line 73 … electromagnetic wave transmitting section 74 … receiving section 75 … evaluates the propagation direction of the apparatus EW 72 electromagnetic wave.