Radome for on-vehicle radar device and production method of the same

Abstract

To provide a radome for an on-vehicle radar device capable of enhancing the reception intensity of reflected waves from electromagnetic waves emitted by the on-vehicle radar device, while ensuring the on-vehicle radar device to stably and accurately detect an angle at which an object exists relative to the vehicle.SOLUTION: A radome for an on-vehicle radar device 1 includes an electromagnetic wave transmissive substrate 2 placed in front of an on-vehicle radar device 10. A linear Fresnel lens portion 22 is formed in an electromagnetic wave irradiation region R on a back face 21 of the substrate 2 facing the on-vehicle radar device 10. A lens groove 221 of the linear Fresnel lens portion 22 is arranged to extend substantially horizontally.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radome for an on-vehicle radar device that is disposed on the electromagnetic wave emitting side of an on-vehicle radar device that transmits and receives electromagnetic waves, and a method for manufacturing the same. [Background technology]

[0002] Conventionally, a radome for an on-board radar device that is placed on the irradiation side of the on-board radar device is disclosed in Patent Document 1. The radome in Patent Document 1 is configured as a vehicle bumper made of resin, with a converging lens formed in a part of the vehicle bumper, and a primary radiator of the on-board radar device disposed near the focal point of the converging lens on the rear side of the vehicle bumper. A Fresnel lens is formed as the converging lens on the rear side of the vehicle bumper, which increases the reception strength of the reflected wave while reducing the height of the converging lens (see Figure 4 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-142913 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, it is very important for an on-board radar device to stably and accurately detect the position of an object in the forward or rearward area of ​​the vehicle. However, if the radiated and reflected electromagnetic waves are refracted in all directions, including the horizontal direction, as in the Fresnel lens of the radome in Patent Document 1, the received strength of the reflected waves can be increased, but there is a problem in that it becomes difficult to stably and accurately detect the angle at which the object is located relative to the vehicle. Therefore, there is a need for a radome that can increase the received strength of the reflected waves of the electromagnetic waves radiated by the on-board radar device and that allows the on-board radar device to stably and accurately detect the angle at which the object is located relative to the vehicle.

[0005] The present invention has been proposed in view of the above-mentioned problems, and aims to provide a radome for an on-board radar device, and a manufacturing method thereof, which can increase the reception strength of the reflected waves of the electromagnetic waves emitted by the on-board radar device, and which allows the on-board radar device to stably and accurately detect the angle at which an object is present relative to the vehicle. [Means for solving the problem]

[0006] The radome for an on-vehicle radar device of the present invention is characterized in that it has an electromagnetic wave transparent base body that is placed in front of the on-vehicle radar device, a linear Fresnel lens portion is formed in an electromagnetic wave irradiation area on the back surface of the base body that faces the on-vehicle radar device, and the lens grooves of the linear Fresnel lens portion are arranged to extend in an approximately horizontal direction. According to this, by arranging the lens grooves of the linear Fresnel lens portion of the base so that they extend substantially horizontally, the electromagnetic waves emitted by the onboard radar device can be irradiated onto an object without being refracted substantially horizontally, and the waves reflected by the object can be received by the onboard radar device without being refracted substantially horizontally. Therefore, the onboard radar device can stably and accurately detect the angle at which the object is located relative to the vehicle. Furthermore, by utilizing the unused vertical radiation width of the electromagnetic waves emitted by the onboard radar device for object detection, the received intensity of the reflected waves of the electromagnetic waves emitted by the onboard radar device can be increased. Furthermore, by providing a linear Fresnel lens portion instead of a conventional lens, the protrusion height from the back side of the radome base can be reduced, thereby reducing the installation space required for installing an onboard radar structure consisting of the radome and the onboard radar device.

[0007] The radome for an on-vehicle radar device of the present invention is characterized in that a heater wire is wired in the electromagnetic wave irradiation region of the base. According to this, by wiring a heater wire in the electromagnetic wave irradiation area of ​​the base, it is possible to melt snow that has adhered to the outer surface of the electromagnetic wave irradiation area of ​​the radome base or to the outer layer of the outer surface of the electromagnetic wave irradiation area of ​​the radome base, and it is possible to maintain good electromagnetic wave transmittance of the radome for an on-vehicle radar device even during snowfall.

[0008] The radome for an on-vehicle radar device of the present invention is characterized in that the heater wire is embedded in the base. According to this, by embedding the heater wire in the radome base, it is possible to achieve a desired wiring shape for the heater wire and stable heat conduction to the desired base. Also, the radome base provided around the heater wire can ensure waterproofing and weather resistance of the heater wire. Furthermore, when the outer surface of the base is to be a designed surface, for example, unevenness on the outer surface of the base due to the installation of the heater wire can be eliminated and smoothness can be ensured.

[0009] The radome for an automotive radar device of the present invention is characterized in that wiring grooves or wiring ridges are formed on the back surface so as to extend in a direction approximately perpendicular to the direction in which the lens grooves extend and cross a plurality of the lens grooves arranged in parallel, the wiring grooves or wiring ridges are arranged side by side at intervals in the direction in which the lens grooves extend, and the heater wire is wired along the wiring grooves or wiring ridges. According to this, by wiring the heater wire along the wiring grooves or wiring ridges formed so as to cross the lens grooves, snow can be melted by wiring the heater wire on the surface of the base facing the vehicle-mounted radar device. Therefore, for example, when the outer surface of the base is used as a design surface, it is possible to eliminate unevenness on the outer surface of the base and ensure smoothness. Furthermore, because the lens portion provided on the base is a linear Fresnel lens portion that is thinner than a normal lens, even if the heater wire is wired along the wiring grooves or wiring ridges formed so as to cross the lens grooves, it is possible to melt the snow that has adhered to the outer surface of the electromagnetic wave irradiation area of ​​the radome base or the outer layer of the outer surface of the electromagnetic wave irradiation area of ​​the radome base.

[0010] The radome for an on-vehicle radar device of the present invention is characterized in that the heater wire is wired on the front surface of the base body on the side opposite to the on-vehicle radar device. This can further enhance the snow melting function for snow adhering to the outer surface of the electromagnetic wave irradiation area of ​​the radome base or snow adhering to the outer layer of the outer surface of the electromagnetic wave irradiation area of ​​the radome base.

[0011] The radome for an on-vehicle radar device of the present invention is characterized in that the heater wire is wired in a serpentine manner so as to have straight portions and folded portions, and the straight portions are arranged so as to extend in a direction approximately perpendicular to the polarization plane of the linearly polarized electromagnetic wave irradiated by the on-vehicle radar device. This increases the transmittance of the base to the electromagnetic waves emitted by the vehicle-mounted radar device, and suppresses the attenuation of the electromagnetic waves due to transmission through the radome base.

[0012] The method for manufacturing a radome for an on-vehicle radar device of the present invention is a method for manufacturing a radome for an on-vehicle radar device of the present invention, characterized by comprising: a first step of laying a heater wire on one surface of an electromagnetically transparent first resin substrate having a linear Fresnel lens portion formed on the other surface thereof; and a second step of insert-molding an electromagnetically transparent second resin substrate so that the second resin substrate is fixed to the other surface of the first resin substrate, forming the base body composed of the first resin substrate and the second resin substrate, and embedding the heater wire in the base body. This allows the heater wire to be easily embedded in the radome base having the linear Fresnel lens portion. Also, the heater wire can be embedded in the first resin base material and the second resin base material in a secure and wide range while being in close contact with each other, thereby further improving the thermal conductivity to the base.

[0013] The method for manufacturing a radome for an on-vehicle radar device of the present invention is a method for manufacturing a radome for an on-vehicle radar device of the present invention, and is characterized by comprising: a first step of laying a heater wire on one surface of an electromagnetically transparent second resin base material, the other surface of which is arranged on the opposite side to the on-vehicle radar device; and a second step of insert-molding an electromagnetically transparent first resin base material so that the first resin base material is fixed to the other surface of the second resin base material, thereby forming the base composed of the first resin base material and the second resin base material, embedding the heater wire in the base, and forming a linear Fresnel lens portion on the surface of the first resin base material opposite to the second resin base material during insert molding. This allows the heater wire to be easily embedded in the radome base having the linear Fresnel lens portion. Also, the heater wire can be embedded in the first resin base material and the second resin base material in a reliable and close contact manner over a wide area, further improving the thermal conductivity to the base. [Effects of the Invention]

[0014] The radome for an on-vehicle radar device of the present invention can increase the reception strength of the reflected waves of the electromagnetic waves emitted by the on-vehicle radar device, and can also enable the on-vehicle radar device to stably and accurately detect the angle at which an object is located relative to the vehicle. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a rear view of a radome for an on-vehicle radar device according to a first embodiment of the present invention; [Figure 2] 1 is a partial cross-sectional explanatory view of a radar structure including a radome for an on-vehicle radar device and the on-vehicle radar device according to a first embodiment; [Figure 3] 5A to 5C are schematic explanatory views illustrating a first example of a manufacturing process for the radome for the on-vehicle radar device according to the first embodiment. [Figure 4] 5A to 5C are schematic explanatory views illustrating a second example of the manufacturing process of the radome for the on-vehicle radar device according to the first embodiment. [Figure 5] FIG. 6 is a rear view of the radome for an on-vehicle radar device according to the second embodiment of the present invention. [Figure 6] Cross section AA of Figure 5. [Figure 7] FIG. 10 is a partial cross-sectional explanatory view of a radar structure including a radome for an on-vehicle radar device and the on-vehicle radar device according to a second embodiment. [Figure 8] 7 is a cross-sectional view corresponding to FIG. 6 of a radome for an on-vehicle radar device according to a modified example of the second embodiment. [Figure 9] FIG. 10 is a rear view of the radome for an on-vehicle radar device according to the third embodiment of the present invention. [Figure 10] FIG. 11 is a partial cross-sectional explanatory view of a radar structure including a radome for an on-vehicle radar device and the on-vehicle radar device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Radome for an on-vehicle radar device according to the first embodiment] A radome 1 for an automotive radar device according to a first embodiment of the present invention is used, for example, as a bumper cover attached to the bumper of a vehicle, and includes an electromagnetic wave-transmitting base 2 that is arranged in front of an automotive radar device 10, as shown in Figures 1 and 2. The base 2 is made up of a first resin base material 3 that is arranged on the opposite side to the viewing side, which is the side of the automotive radar device 10, and a second resin base material 4 that is arranged on the viewing side, which is in front of the first resin base material 3, and the first resin base material 3 and the second resin base material 4 are arranged in a layered manner and fixed to each other by welding or the like.

[0017] The first resin base material 3 and the second resin base material 4 are each formed of an insulating, electromagnetically transparent synthetic resin. The first resin base material 3 and the second resin base material 4 can be formed into any suitable shape within the applicable range, such as a flat plate or a curved plate. The first resin base material 3 and the second resin base material 4 can be made of different or the same synthetic resin. From the perspective of improving electromagnetic wave transmission performance, it is preferable to form the first resin base material 3 and the second resin base material 4 from materials whose refractive indices n, defined based on the complex dielectric constant, match or whose refractive indices n are approximately the same or close to each other. The numerical range of the refractive indices of the first resin base material 3 and the second resin base material 4 that are close to each other is preferably a difference of 0 to 10%.

[0018] Here, the refractive index n is a quantity defined by the real part of the relative dielectric constant εr' and the imaginary part of the relative dielectric constant εr" as in Equation 1. From the perspective of transparency, it is preferable that the magnitude of the dielectric loss tangent tanδ, defined by Equation 2 from the ratio of the imaginary part to the real part at the applicable frequency, be 0.1 or less. It is also preferable that the magnitude of the real part of the relative dielectric constant be 3 or less. By keeping the magnitudes of the dielectric loss tangent and the real part of the relative dielectric constant at these values ​​or less, it is possible to ensure the reduction of the reflectivity and internal loss required for the radome.

[0019]

number

[0020]

number

[0021] Any suitable synthetic resin can be used within the spirit and scope of the present invention for the first resin substrate 3 and the second resin substrate 4. Examples of suitable synthetic resins include acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene-acrylate copolymer (ASA), acrylonitrile-ethylenepropyl rubber-styrene copolymer (AES), polypropylene (PP), polyphenylene ether (PPE), modified polyphenylene ether (m-PPE), and polystyrene (PS), either alone or in combination, and additives may be added. Foams may also be used for these synthetic resins. Furthermore, with regard to the thicknesses of the first resin base material 3 and the second resin base material 4 in the electromagnetic wave transmission direction, the ratio of the thickness of the first resin base material 3 to the thickness of the second resin base material 4, the thickness of the first base material resin 3, the thickness of the second resin base material 4, and the total thickness of the base 2 composed of the first resin base material 3 and the second resin base material 4 are appropriate within a range that can ensure the required electromagnetic wave transmission properties of the snow-melting radome 1.

[0022] A linear Fresnel lens portion 22 is formed in the electromagnetic wave irradiation region R on the surface of the first resin base material 3 facing the on-board radar device 10, which corresponds to the electromagnetic wave irradiation region R on the back surface 21 facing the on-board radar device 10 of the base 2, and the lens grooves 221 of the linear Fresnel lens portion 22 are arranged to extend in a substantially horizontal direction. The substantially horizontal direction in which the lens grooves 221 extend has an inclination angle with respect to the horizontal direction of preferably 5° or less, and more preferably 3° or less.

[0023] The linear Fresnel lens portion 22 is formed so as to refract the electromagnetic waves irradiated from the vehicle-mounted radar device 10 arranged behind the base 2 so as to narrow the radiation width in the vertical direction when radiated from the front surface 23 of the base 2, and to refract the reflected waves incident from the front surface 23 of the base 2 so as to converge in the vertical direction toward the vehicle-mounted radar device 10 when radiated from the back surface 21 of the base 2 or the linear Fresnel lens portion 22.

[0024] A heater wire 5 is wired in the electromagnetic wave irradiation region R of the base 2, and the heater wire 5 is wired in a predetermined pattern along the surface of the electromagnetic wave-transmitting base 2 so as to exhibit snow-melting function in the electromagnetic wave-transmitting region R. Any appropriate conductive material can be used for the heater wire 5 within the spirit and scope of the present invention, and preferred examples include copper, silver, silver-plated copper, copper-silver alloy, copper-nickel alloy, nickel-chromium alloy, iron-chromium alloy, transparent conductive film such as ITO film, and carbon fiber. Furthermore, the heater wire can be in any form, including wire, conductive ink, and conductive filler-added materials.

[0025] The heater wire 5 in the first embodiment is embedded in the base 2, and is embedded between the first resin base material 3 and the second resin base material 4. The heater wire 5 in the first embodiment is wired in a serpentine manner to have straight portions 51 and folded portions 52, and the straight portions 51 extend in a direction substantially perpendicular to the extension direction of the lens grooves 221 and are wired so as to cross the plurality of lens grooves 221 arranged in parallel. The direction in which the straight portions 51 extend substantially perpendicular to the extension direction of the lens grooves 221 is preferably inclined at an angle of 5° or less with respect to the direction perpendicular to the extension direction of the lens grooves 221, and more preferably at an angle of 3° or less.

[0026] When the on-board radar device 10 irradiates linearly polarized electromagnetic waves, it is preferable from the viewpoint of improving electromagnetic wave transmittance to arrange the straight portion 51 of the serpentine wiring of the heater wire 5 so that it extends in a direction approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-board radar device 10. When using an on-board radar device 10 that irradiates linearly polarized electromagnetic waves in the first embodiment, it is preferable that the polarization plane of the linearly polarized electromagnetic waves be approximately horizontal and approximately perpendicular to the straight portion 51 of the heater wire 5 that extends in the vertical direction.

[0027] In the first embodiment, both ends of the continuously extending heater wire 5 are connected to a wire harness 7 at connection parts 6 in the outer region of the electromagnetic wave irradiation region R of the base 2, so that current is supplied to the heater wire 5 via the wire harness 7.

[0028] When manufacturing the radome 1 for an automotive radar device of the first embodiment, for example, as in the first example shown in Fig. 3 , an electromagnetically transparent first resin base material 3 having a linear Fresnel lens portion 22 formed on one surface is formed, the heater wire 5 is laid in a predetermined pattern on the other surface of the first resin base material 3, and the wire harness 7 is connected to both ends of the heater wire 5. Then, the first resin base material 3 on which the heater wire 5 is laid is placed inside a mold 100 consisting of a split mold, and the wire harness 7 connected to the heater wire 5 is led out of the mold 100 from an outlet formed in a part of the mold 100.

[0029] Thereafter, molten resin MR is poured into the interior of the mold 100 through the injection port 101 of the mold 100 to perform injection molding, and an electromagnetic wave transparent second resin base material 4 is insert molded so as to be fixed to the other surface of the first resin base material 3 by molding welding, thereby forming a base 2 composed of the first resin base material 3 and the second resin base material 4, and a heater wire 5 is embedded in the base 2.

[0030] The radome 1 for an automotive radar device of the first embodiment may also be suitably manufactured as in the second example shown in Fig. 4. In the second example, an electromagnetically transparent second resin base material 4 is formed, one surface of which is located on the opposite side from the automotive radar device 10, a heater wire 5 is laid in a predetermined pattern on the other surface of the second resin base material 4, and a wire harness 7 is connected to both ends of the heater wire 5. Then, the second resin base material 4 on which the heater wire 5 is laid is placed inside a mold 100m consisting of a split mold, and the wire harness 7 connected to the heater wire 5 is led out of the mold 100m from a lead-out port formed in part of the mold 100m.

[0031] Thereafter, molten resin MR is poured into the interior of the mold 100m through an injection port 101m of the mold 100m to perform injection molding, and an electromagnetic wave transparent first resin base material 3 is insert molded so as to be fixed to the other surface of the second resin base material 4 by molding welding, forming a base 2 composed of the first resin base material 3 and the second resin base material 4, and the heater wire 5 is embedded in the base 2. During this insert molding by injection molding, a linear Fresnel lens portion 22 is formed on the surface of the first resin base material 3 opposite to the second resin base material 4, due to the shape formed on the inner wall of the mold 100m.

[0032] According to the radome 1 for an automotive radar device of the first embodiment, the lens grooves 221 of the linear Fresnel lens portion 22 of the base 2 are arranged to extend in a substantially horizontal direction. This allows the electromagnetic waves emitted by the automotive radar device 10 to be irradiated onto an object without being refracted in a substantially horizontal direction, and the reflected waves reflected by the object to be received by the automotive radar device 10 without being refracted in a substantially horizontal direction. This allows the automotive radar device 10 to stably and accurately detect the angle at which the object is located relative to the vehicle. Furthermore, the unused vertical radiation width of the electromagnetic waves emitted by the automotive radar device 10 can be utilized for detecting the object, thereby increasing the reception strength of the reflected waves of the electromagnetic waves emitted by the automotive radar device 10. Furthermore, by providing the linear Fresnel lens portion 22 instead of a normal lens, the protrusion height of the radome base 2 from the rear side can be reduced, thereby reducing the installation space required for installing the automotive radar structure composed of the radome 1 and the automotive radar device 10.

[0033] Furthermore, by wiring the heater wire 5 in the electromagnetic wave irradiation area R of the base 2, it is possible to melt snow adhering to the outer surface of the electromagnetic wave irradiation area of ​​the radome base 2 or snow adhering to the outer layer of the outer surface of the electromagnetic wave irradiation area of ​​the radome base 2, and it is possible to maintain good electromagnetic wave transmittance of the radome 1 for an automotive radar device even during snowfall.

[0034] Furthermore, by embedding the heater wire 5 in the radome base 2, it is possible to achieve a desired wiring shape for the heater wire 5 and to stably conduct heat to the desired base 2. Furthermore, the radome base 2 provided around the heater wire 5 can ensure the waterproofness and weather resistance of the heater wire 5. Furthermore, when the outer surface of the base 2 is to be a designed surface, for example, unevenness on the outer surface of the base 2 due to the installation of the heater wire 5 can be eliminated and smoothness can be ensured.

[0035] Furthermore, when using an on-board radar device 10 that irradiates linearly polarized electromagnetic waves, the heater wire 5 is wired in a serpentine manner so that the straight portion 51 thereof extends in a direction approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-board radar device 10, thereby increasing the transmittance of the base 2 to the electromagnetic waves irradiated by the on-board radar device 10 and suppressing attenuation of the electromagnetic waves due to transmission through the radome base 2.

[0036] Furthermore, when manufacturing the radome 1 for an automotive radar device of the first embodiment in the first or second example, the heater wire 5 can be easily embedded in the radome base 2 having the linear Fresnel lens portion 22. Furthermore, the heater wire 5 can be embedded reliably and in close contact with the first resin base material 3 and the second resin base material 4 over a wide range, and the thermal conductivity to the base 2 can be further improved.

[0037] [Radome for an automotive radar device according to the second embodiment] The radome 1a for an automotive radar device according to the second embodiment of the present invention is also used, for example, as a bumper cover attached to the bumper of a vehicle, and includes an electromagnetic wave-transmitting base body 2a that is arranged in front of the automotive radar device 10, as shown in Figures 5 to 7. The base body 2a is an integrally molded product formed by injection molding or the like using the same material as the first resin base material 3 or the second resin base material 4 in the first embodiment, but it is also possible to configure the radome 1a by stacking the first resin base material 3 and the second resin base material 4, etc., and fixing them to each other by welding or the like, as in the first embodiment.

[0038] A linear Fresnel lens portion 22a is formed in the electromagnetic wave irradiation region R on the back surface 21a of the base 2a facing the on-vehicle radar device 10, and the lens grooves 221a of the linear Fresnel lens portion 22a are arranged to extend in a substantially horizontal direction. The substantially horizontal direction in which the lens grooves 221a extend is preferably inclined at an angle of 5° or less, more preferably 3° or less, relative to the horizontal direction. The linear Fresnel lens portion 22a and the front surface 23a of the base 2a are formed to perform the same refraction as the linear Fresnel lens portion 22 and the front surface 23 in the first embodiment.

[0039] On the back surface 21a of the base 2a, wiring grooves 24a are formed so as to extend in a direction approximately perpendicular to the direction in which the lens grooves 221a extend and cross the multiple lens grooves 221a arranged in parallel, and the wiring grooves 24a are arranged side by side at intervals in the direction in which the lens grooves 221a extend.

[0040] Furthermore, a heater wire 5a is wired in the electromagnetic wave irradiation region R of the base 2a, and the heater wire 5a is wired in a predetermined pattern in the surface direction of the electromagnetic wave-transmitting base 2a so as to exhibit a snow-melting function in the electromagnetic wave-transmitting region R. The conductive material and shape of the heater wire 5a are the same as those of the heater wire 5 in the first embodiment. The heater wire 5a in the second embodiment is also wired in a meandering manner to provide straight portions 51a and folded portions 52a, and the straight portions 51a extend in a direction substantially perpendicular to the extension direction of the lens grooves 221a and cross the plurality of lens grooves 221a arranged in parallel. The direction in which the straight portions 51a extend substantially perpendicular to the extension direction of the lens grooves 221a is preferably inclined at an angle of 5° or less, more preferably 3° or less, with respect to the direction perpendicular to the extension direction of the lens grooves 221a.

[0041] The heater wire 5a in the second embodiment is wired so as to follow the wiring groove 24a, and the straight portion 51a of the heater wire 5a is provided in the wiring groove 24a, and the straight portion 51a is wired in the wiring groove 24a along the wiring groove 24a.

[0042] 8, instead of the wiring grooves 24a, it is also preferable to form wiring ridges 25a on the back surface 21a of the base 2a so as to extend in a direction substantially perpendicular to the extension direction of the lens grooves 221a and cross a plurality of parallel-arranged lens grooves 221a, and to arrange the wiring ridges 25a in parallel at intervals in the extension direction of the lens grooves 221a, and to wire the heater wires 5a along the wiring ridges 25a. When wiring the heater wires 5a along the wiring ridges 25a, for example, tapered inclined portions 251a extending from the back surface 21a of the base 2a to the height of the wiring ridges 25a may be provided at both ends of the wiring ridges 25a, and the straight portions 51a of the heater wires 5a may be placed on the tops of the wiring ridges 25a so as to wire the straight portions 51a along the wiring ridges 25a.

[0043] In the second embodiment as well, when the on-vehicle radar device 10 irradiates linearly polarized electromagnetic waves, it is preferable from the viewpoint of improving electromagnetic wave transmittance to arrange the straight portion 51a of the serpentine wiring of the heater wire 5a so that it extends in a direction substantially perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device 10. Moreover, both ends of the continuously extending heater wire 5a in the second embodiment are also connected to the wire harness 7a at connection portions 6a, respectively, in the region outside the electromagnetic wave irradiation region R of the base 2a, so that a current is supplied to the heater wire 5a via the wire harness 7a.

[0044] The radome 1a for an on-vehicle radar device of the second embodiment can achieve corresponding effects from the configuration corresponding to that of the first embodiment. Furthermore, by routing the heater wire 5a along the wiring groove 24a or wiring ridge 25a formed so as to cross the lens groove 221a, snow can be melted by routing the heater wire 5a on the surface of the base 2a facing the on-vehicle radar device 10. Therefore, for example, when the outer surface of the base 2a is a design surface, it is possible to eliminate unevenness on the outer surface of the base 2a and ensure smoothness. Furthermore, since the lens portion provided on the base 2a is the linear Fresnel lens portion 22a, which is thinner than a normal lens, the necessary snow melting can be achieved for snow adhering to the outer surface of the electromagnetic wave irradiation region R of the radome base 2a or the outer layer of the outer surface of the electromagnetic wave irradiation region R of the radome base 2a, even if the heater wire 5a is routed along the wiring groove 24a or wiring ridge 25a formed so as to cross the lens groove 221a.

[0045] [Radome for an on-vehicle radar device according to the third embodiment] A radome 1b for an automotive radar device according to the third embodiment of the present invention is also used, for example, as a bumper cover attached to the bumper of a vehicle, and includes an electromagnetic wave-transmitting base 2b arranged in front of the automotive radar device 10, as shown in Figures 9 and 10. The base 2b is an integrally molded product formed by injection molding or the like using the same material as the first resin base material 3 or the second resin base material 4 in the first embodiment, but it is also possible to configure the radome 1b by stacking the first resin base material 3 and the second resin base material 4 and fixing them to each other by welding or the like, as in the first embodiment.

[0046] A linear Fresnel lens portion 22b is formed in the electromagnetic wave irradiation region R on the back surface 21b of the base 2b facing the on-vehicle radar device 10, and the lens grooves 221b of the linear Fresnel lens portion 22b are arranged to extend in a substantially horizontal direction. The substantially horizontal direction in which the lens grooves 221b extend is preferably inclined at an angle of 5° or less, more preferably 3° or less, relative to the horizontal direction. The linear Fresnel lens portion 22b and the front surface 23b of the base 2b are formed to perform the same refraction as the linear Fresnel lens portion 22 and the front surface 23 in the first embodiment.

[0047] A heater wire 5b is wired in the electromagnetic wave irradiation region R of the base 2b, and the heater wire 5b is wired in a predetermined pattern in the surface direction of the electromagnetic wave-transmitting base 2b so as to exhibit a snow-melting function in the electromagnetic wave-transmitting region R. The conductive material and shape of the heater wire 5b are the same as those of the heater wire 5 in the first embodiment. The heater wire 5b in the third embodiment is also wired in a meandering manner to provide straight portions 51b and folded portions 52b, and the straight portions 51b extend in a direction substantially perpendicular to the extension direction of the lens grooves 221b and cross the plurality of lens grooves 221b arranged in parallel. The direction in which the straight portions 51b extend substantially perpendicular to the extension direction of the lens grooves 221b is preferably inclined at an angle of 5° or less, more preferably 3° or less, with respect to the direction perpendicular to the extension direction of the lens grooves 221b.

[0048] The heater wire 5b in the third embodiment is laid on the front surface 23b of the base 2b on the side opposite to the in-vehicle radar device 10, and the heater wire 5b is laid in a meandering pattern on the surface of the front surface 23b.

[0049] In the third embodiment as well, when the on-vehicle radar device 10 irradiates linearly polarized electromagnetic waves, it is preferable from the viewpoint of improving electromagnetic wave transmittance to arrange the straight portion 51b of the meandering wiring of the heater wire 5b so as to extend in a direction approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the on-vehicle radar device 10. Moreover, both ends of the continuously extending heater wire 5b in the third embodiment are also connected to the wire harness 7b at connection portions 6b, respectively, in the region outside the electromagnetic wave irradiation region R of the base 2b, so that a current is supplied to the heater wire 5b via the wire harness 7b.

[0050] The radome 1b for an automotive radar device of the third embodiment can achieve the same effects as those of the first embodiment due to the configuration corresponding to that of the first embodiment. In addition, since the heater wire 5b is routed on the front surface 23b of the base 23b, it is possible to further improve the snow melting function for snow adhering to the outer surface of the electromagnetic wave irradiation region R of the radome base 2b or snow adhering to the outer layer of the outer surface of the electromagnetic wave irradiation region R of the radome base 2b.

[0051] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the individual inventions and embodiments listed as inventions, those specified by modifying partial contents of these with other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial effects are obtained and creating a generic concept. The inventions disclosed in this specification also include the following modifications and additions.

[0052] For example, in the first to third embodiments, the heater wires 5, 5a, and 5b are wired in a serpentine manner, but the wiring shape or wiring pattern when wiring the heater wires in the radome for an on-vehicle radar device of the present invention may be any appropriate one within the scope of the present invention and is not limited to serpentine wiring. Furthermore, in the radome for an on-vehicle radar device of the present invention, when the heater wire is wired in a serpentine manner so as to have straight portions and folded portions, it is also possible to configure the straight portions of the heater wire to extend in a direction approximately parallel to the polarization plane of the linearly polarized electromagnetic wave irradiated by the on-vehicle radar device.

[0053] The radome for an on-vehicle radar device of the present invention also includes one having a configuration in which a linear Fresnel lens portion is formed in an electromagnetic wave irradiation area on the back surface of an electromagnetic wave-transparent base facing the on-vehicle radar device, and the lens grooves of the linear Fresnel lens portion are arranged to extend in a substantially horizontal direction, and also includes a radome for an on-vehicle radar device in which no heater wire is wired. [Industrial Applicability]

[0054] The present invention can be used in a radome for an on-vehicle radar device that is disposed in front of the on-vehicle radar device. [Explanation of symbols]

[0055] REFERENCE SIGNS LIST 1, 1a, 1b...Radome for on-vehicle radar device 2, 2a, 2b...Base 21, 21a, 21b...Rear surface 22, 22a, 22b...Linear Fresnel lens portion 221, 221a, 221b...Lens groove 23, 23a, 23b...Front surface 24a...Wiring groove 25a...Wiring ridge 251a...Sloped portion 3...First resin substrate 4...Second resin substrate 5, 5a, 5b...Heater wire 51, 51a, 51b...Straight portion 52, 52a, 52b...Folded portion 6, 6a, 6b...Connection portion 7, 7a, 7b...Wire harness 10...On-vehicle radar device 100, 100m...Mold 101, 101m...Injection port R...Electromagnetic wave transmission region MR...Molten resin

Claims

1. an electromagnetic wave transparent substrate disposed in front of the vehicle-mounted radar device; a linear Fresnel lens portion is formed in an electromagnetic wave irradiation area on the back surface of the base body on the side of the on-vehicle radar device; 2. A radome for an on-vehicle radar device, wherein the lens grooves of the linear Fresnel lens portion are arranged to extend in a substantially horizontal direction.

2. 2. The radome for an on-vehicle radar device according to claim 1, wherein a heater wire is wired in an electromagnetic wave irradiation area of ​​said base.

3. 3. The radome for an on-vehicle radar device according to claim 2, wherein the heater wire is embedded in the base.

4. a wiring groove or a wiring ridge is formed on the rear surface so as to extend in a direction substantially perpendicular to the direction in which the lens grooves extend and to cross the plurality of lens grooves arranged in parallel; the wiring grooves or the wiring ridges are arranged in parallel at intervals in the extending direction of the lens groove, 3. The radome for an on-vehicle radar device according to claim 2, wherein the heater wire is routed along the wiring groove or the wiring ridge.

5. 3. The radome for an on-vehicle radar device according to claim 2, wherein the heater wire is wired on the front surface of the base body on the side opposite to the on-vehicle radar device.

6. The heater wire is wired in a meandering manner so as to have a straight portion and a folded portion, The radome for an on-vehicle radar device according to any one of claims 2 to 5, characterized in that the linear portion is arranged to extend in a direction approximately perpendicular to the polarization plane of the linearly polarized electromagnetic wave irradiated by the on-vehicle radar device.

7. A method for manufacturing a radome for an on-vehicle radar device according to claim 3, a first step of laying a heater wire on one surface of an electromagnetic wave-transmitting first resin substrate having a linear Fresnel lens portion formed on the other surface; a second step of insert-molding an electromagnetic wave-transmitting second resin base material so as to be fixed to the other surface of the first resin base material, forming the base body composed of the first resin base material and the second resin base material, and embedding the heater wire in the base body.

8. A method for manufacturing a radome for an on-vehicle radar device according to claim 3, a first step of laying a heater wire on one surface of an electromagnetically transparent second resin substrate, the other surface of which is disposed on the opposite side from the on-vehicle radar device; a second step of insert-molding an electromagnetic wave-transmitting first resin base material so as to be fixed to the other surface of the second resin base material, forming the base body composed of the first resin base material and the second resin base material, embedding the heater wire in the base body, and forming a linear Fresnel lens portion on the surface of the first resin base material opposite to the second resin base material during insert molding.

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