Snow melting radome

Abstract

To provide a snow melting radome that can increase the design properties of an outer surface side of the snow melting radome visually recognized from the outside, and can save an installation space of the snow melting radome.SOLUTION: A snow melting radome 1 has an electromagnetic wave transmissive substrate 2 arranged on the front of a radar device 10, has a Fresnel lens part formed in an electromagnetic wave irradiation region R on a surface on the radar device 10 side of the substrate 2, and has a heater line 5 wired to substantially follow a direction in which a lens groove of the Fresnel lens part extends and the position of a bottom part of the lens groove. Preferably, the heater line 5 is wired to substantially follow a direction in which a lens groove 221 of the linear Fresnel lens part 22 extends and the position of a bottom part 222 of the lens groove 221.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a snow-melting radome that is arranged on the electromagnetic wave emitting side of a radar device that transmits and receives electromagnetic waves. [Background technology]

[0002] Conventionally, a snow-melting radome placed on the irradiation side of a radar device that transmits and receives electromagnetic waves is the snow-melting radome shown as a dielectric lens antenna in Patent Document 1. The snow-melting radome in Patent Document 1 is configured by arranging a heating element made up of multiple linear heating wires connected in series on the outer surface of a plano-convex dielectric lens with the convex side facing outward, or on the outer surface of a matching layer formed on the outer surface of the dielectric lens, and is capable of melting snow that has adhered to the outer surface of the dielectric lens or the outer surface of the matching layer (see Figures 1 and 2 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3650953 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the snow melting radome shown as a dielectric lens antenna in Patent Document 1 is arranged so that the convex side of the plano-convex dielectric lens protrudes outward, which restricts the design freedom of the convex shape of the plano-convex lens, resulting in a problem of reduced designability of the outer surface side of the radome.In addition, it is desirable to further reduce the installation space required for snow melting radomes installed on vehicles, etc.

[0005] The present invention has been proposed in view of the above-mentioned problems, and aims to provide a snow melting radome that can improve the design of the outer surface side of the snow melting radome that is visible from the outside, and that can reduce the installation space of the snow melting radome. [Means for solving the problem]

[0006] The snow-melting radome of the present invention is characterized in that it has an electromagnetic wave-transmitting base body that is placed in front of a radar device, a Fresnel lens portion is formed in the electromagnetic wave irradiation area on the surface of the base body facing the radar device, and a heater wire is wired so as to roughly follow the extension direction of the lens groove of the Fresnel lens portion and the position of the bottom of the lens groove. According to this, by forming a Fresnel lens portion in the electromagnetic wave irradiation area on the radar device side of the base, it is not necessary to form a convex shape on the outer surface of the radome, which increases the design freedom of the outer surface of the radome and improves the design of the outer surface of the snow-melting radome visible from the outside. Furthermore, by forming the lens portion on the base as a Fresnel lens portion, the thickness of the radome base and the protrusion height to the back side of the radome base can be reduced, thereby saving the installation space required for installing the snow-melting radome and the radar structure composed of the snow-melting radome and the radar device. Furthermore, by wiring the heater wire so that it roughly follows the extension direction of the lens groove of the Fresnel lens portion and the position of the bottom of the lens groove, parts of the base that do not contribute or have a low contribution to radar device detection can be effectively used to obtain the desired snow-melting function, and the attenuation of the electromagnetic waves emitted by the radar device and the reflected waves due to the installation of the heater wire can be significantly reduced.

[0007] The snow-melting radome of the present invention is characterized in that the Fresnel lens portion is a linear Fresnel lens portion, is arranged in front of the vehicle-mounted radar device, and has the lens grooves of the linear Fresnel lens portion 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 in a substantially horizontal direction, the electromagnetic waves emitted by the on-board radar device can be irradiated onto an object without being refracted in a substantially horizontal direction, and the waves reflected by the object can be received by the on-board radar device without being refracted in a substantially horizontal direction. Therefore, the on-board radar device can stably and accurately detect the angle at which the object is located relative to the vehicle. Furthermore, by utilizing the vertical radiation width of the electromagnetic waves emitted by the on-board radar device, which is not actively used, for detecting objects, the received strength of the reflected waves of the electromagnetic waves emitted by the on-board radar device can be increased.

[0008] The snow melting radome of the present invention is characterized in that the heater wire is embedded in the base body. According to this, by embedding the heater wire in the radome base, it is possible to stably route the heater wire as desired and conduct heat to the desired base. Also, the radome base provided around the heater wire can ensure the waterproof and weather resistance of the heater wire. Furthermore, when the outer surface of the base is used as a design surface, for example, it is possible to eliminate unevenness on the outer surface of the base due to the installation of the heater wire and ensure smoothness.

[0009] The snow melting radome of the present invention is characterized in that the heater wire is wired so as to be disposed at the bottom of the lens groove. By arranging the heater wire at the bottom of the lens groove, it is possible to effectively utilize the parts of the base that do not contribute or have a low contribution to radar detection in order to obtain the desired snow melting function, and it is possible to significantly reduce the attenuation of the electromagnetic waves emitted by the radar and the reflected waves due to the installation of the heater wire. Furthermore, 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 due to the installation of the heater wire and ensure smoothness.

[0010] The snow melting radome of the present invention is characterized in that the heater wire is wired on the surface of the base opposite to the 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 snow-melting radome of the present invention is characterized in that an electromagnetic wave-transmitting back substrate is laminated on the radar device side of the base and is in close contact with the base, the protrusions of the back substrate are arranged to engage with the lens grooves, and the heater wire is wired on the surface of the back substrate facing the radar device. This allows the heater wire to be routed on the radar device side of the back substrate, making it easier to arrange the heater wire in the desired shape than when it is directly installed at the bottom of the lens groove. Also, when the outer surface of the substrate is used as a design surface, for example, it is possible to eliminate unevenness on the outer surface of the substrate due to the installation of the heater wire and ensure smoothness.

[0012] The snow-melting radome of the present invention is characterized in that an electromagnetic wave-transmitting back substrate is laminated on the radar device side of the base and is in close contact with the base, the protrusions of the back substrate are arranged to engage with the lens grooves, and the heater wire is embedded in the back substrate. According to this, by embedding the heater wire in the back substrate, it is possible to achieve a desired wiring shape for the heater wire and stable heat conduction to the desired substrate. Furthermore, the back substrate provided around the heater wire ensures the waterproof and weather resistance of the heater wire. Furthermore, for example, when the outer surface of the substrate is to be a designed surface, it is possible to eliminate unevenness on the outer surface of the substrate due to the installation of the heater wire and ensure smoothness.

[0013] The snow melting radome of the present invention is characterized in that the Fresnel lens portion is a circular Fresnel lens portion, and part of the heater wire is wired so as to be bridged between the concentric lens grooves when viewed from the front of the radome. According to this, even when the Fresnel lens portion is a circular Fresnel lens portion, it is possible to minimize the attenuation of the electromagnetic waves and reflected waves emitted by the radar device due to the installation of the heater wire, while effectively utilizing parts of the base that do not contribute or have a low contribution to the detection of the radar device, thereby obtaining the desired snow melting function. [Effects of the Invention]

[0014] According to the snow melting radome of the present invention, it is possible to improve the design of the outer surface side of the snow melting radome that is visible from the outside, and also to save the installation space of the snow melting radome. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a rear view of the snow melting radome of the first embodiment according to the present invention. [Figure 2] 1 is a partial cross-sectional explanatory diagram of a radar structure composed of a snow melting radome and a radar device according to a first embodiment. FIG. [Figure 3] FIG. 4 is a rear view of the snow melting radome of the second embodiment according to the present invention. [Figure 4] FIG. 10 is a partial cross-sectional explanatory diagram of a radar structure composed of a snow melting radome and a radar device according to a second embodiment. [Figure 5] FIG. 10 is a rear view of the snow melting radome of the third embodiment according to the present invention. [Figure 6] FIG. 11 is a partial cross-sectional explanatory diagram of a radar structure including a snow melting radome and a radar device according to a third embodiment. [Figure 7] FIG. 10 is a rear view of the snow melting radome of the fourth embodiment according to the present invention. [Figure 8] FIG. 10 is a partial cross-sectional explanatory diagram of a radar structure including a snow melting radome and a radar device according to a fourth embodiment. [Figure 9] FIG. 10 is a rear view of the snow melting radome of the fifth embodiment according to the present invention. [Figure 10] FIG. 10 is an explanatory cross-sectional view taken along the line AA of a radar structure including a snow-melting radome and a radar device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Snow-melting radome of the first embodiment] A snow melting radome 1 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 transparent base body 2 that is arranged in front of a radar device 10, such as an on-vehicle radar device, as shown in Figures 1 and 2. The base body 2 is composed of a first resin base material 3 that is arranged on the opposite side to the viewing side, which is the radar device 10 side, for example, 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] In the electromagnetic wave irradiation area R on the radar device 10 side surface of the first resin base material 3, which corresponds to the electromagnetic wave irradiation area R on the radar device 10 side back surface 21 of the base 2, a linear Fresnel lens portion 22 is formed as a Fresnel lens portion, 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 of the linear Fresnel lens portion 22 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 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 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 so as to have straight portions 51 and folded portions 52, and the heater wire 5 is wired so as to approximately follow the extending direction of the lens grooves 221 of the Fresnel lens portion 22 and the positions of the bottoms 222 of the lens grooves 221, more specifically, the straight portions 51 of the heater wire 5 are wired so as to follow the extending direction of the lens grooves 221 of the Fresnel lens portion 22 and the positions of the bottoms 222 of the lens grooves 221.

[0026] When the 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 radar device 10. When the radar device 10 that irradiates linearly polarized electromagnetic waves is used in the first embodiment, it is preferable that the polarization plane of the linearly polarized electromagnetic waves be approximately vertical and approximately perpendicular to the straight portion 51 of the heater wire 5 that extends in the horizontal 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] According to the snow melting radome 1 of the first embodiment, by forming a linear Fresnel lens portion 22 as a Fresnel lens portion in the electromagnetic wave irradiation region R on the surface of the base 2 facing the radar device 10, it is possible to eliminate the need to form a convex shape on the outer surface of the radome, thereby increasing the degree of freedom in designing the outer surface side of the radome and improving the design of the outer surface side of the snow melting radome 1 that is visible from the outside. Furthermore, by forming the lens portion on the base 2 as the linear Fresnel lens portion 22, which is a Fresnel lens portion, it is possible to reduce the thickness of the radome base 2 and the protrusion height to the back side of the radome base 2, thereby saving the installation space required for installing the snow melting radome 1 and the radar structure composed of the snow melting radome 1 and the radar device 10. Furthermore, by wiring the heater wire 5 so as to roughly follow the direction in which the lens groove 221 of the linear Fresnel lens portion 22, which is the Fresnel lens portion, extends and the position of the bottom 222 of the lens groove 221, it is possible to effectively utilize the parts of the base 2 that do not contribute or have a low contribution to the detection of the radar device 10 in order to obtain the desired snow melting function, and it is also possible to significantly reduce the attenuation of the electromagnetic waves and reflected waves radiated by the radar device 10 due to the installation of the heater wire 5.

[0029] Furthermore, when the radar device 10 is used as an on-vehicle radar device, by arranging the lens grooves 221 of the linear Fresnel lens portion 22 of the base 2 so that they extend in a substantially horizontal direction, the electromagnetic waves emitted by the on-vehicle radar device can be irradiated onto an object without being refracted in a substantially horizontal direction, and the waves reflected by the object can be received by the on-vehicle radar device without being refracted in a substantially horizontal direction. This allows the on-vehicle radar device to stably and accurately detect the angle at which the object is located relative to the vehicle. Furthermore, by utilizing the vertical radiation width of the electromagnetic waves emitted by the on-vehicle radar device, which is not actively used, for detecting objects, the received strength of the reflected waves of the electromagnetic waves emitted by the on-vehicle radar device can be increased.

[0030] 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.

[0031] [Snow-melting radome of the second embodiment] The snow melting radome 1a of the second embodiment according to the present invention is also used, for example, as a bumper cover attached to the bumper of a vehicle, and includes an electromagnetic wave transparent base body 2a arranged in front of the radar device 10, as shown in Figures 3 and 4. 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 it 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.

[0032] A linear Fresnel lens portion 22a is formed as a Fresnel lens portion in the electromagnetic wave irradiation region R of the back surface 21a of the base 2a facing the 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 refraction similar to that of the linear Fresnel lens portion 22 and the front surface 23 in the first embodiment.

[0033] 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 permeable base 2a so as to exert a snow melting function in the electromagnetic wave permeable 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.

[0034] The heater wire 5a in the second embodiment is also routed in a serpentine manner to have straight portions 51a and folded portions 52a, and is routed so as to roughly follow the extension direction of the lens grooves 221a of the linear Fresnel lens portion 22a and the positions of the bottoms 222a of the lens grooves 221a. The heater wire 5a in the second embodiment is routed so as to be disposed at the bottoms 222a of the lens grooves 221a on the back surface 21a, more specifically, so that the straight portions 51a of the heater wire 5a are disposed at the bottoms 222a of the lens grooves 221a on the back surface 21a.

[0035] In the second embodiment as well, when the radar device 10 irradiates linearly polarized electromagnetic waves, it is preferable from the viewpoint of improving electromagnetic wave transmittance to arrange the straight line portion 51a of the meandering 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 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.

[0036] The snow melting radome 1a of the second embodiment can achieve the same effects as those of the first embodiment through a configuration corresponding to that of the first embodiment. Furthermore, by disposing the heater wire 5a at the bottom 222a of the lens groove 221a, it is possible to effectively utilize the parts of the base that do not contribute or contribute little to the detection of the radar device 10 to obtain the desired snow melting function, and it is possible to significantly reduce the attenuation of the electromagnetic waves and reflected waves emitted by the radar device 10 due to the installation of the heater wire 5a. Furthermore, for example, when the outer surface of the base 2a is to be a decorative surface, it is possible to eliminate unevenness on the outer surface of the base 2a due to the installation of the heater wire 5a, thereby ensuring smoothness.

[0037] [Snow-melting radome of the third embodiment] The snow melting radome 1b of the third embodiment according to the present invention is also used, for example, as a bumper cover attached to the bumper of a vehicle, and includes an electromagnetic wave transparent base body 2b arranged in front of the radar device 10, as shown in Figures 5 and 6. The base body 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 it 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 22b is formed as a Fresnel lens portion in the electromagnetic wave irradiation region R of the back surface 21b of the base 2b facing the 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 refraction similar to that of the linear Fresnel lens portion 22 and the front surface 23 in the first embodiment.

[0039] Furthermore, 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 permeable base 2b so as to exert a snow melting function in the electromagnetic wave permeable 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.

[0040] The heater wire 5b in the third embodiment is also routed in a meandering manner to have straight portions 51b and folded portions 52b, and is routed so as to approximately follow the extension direction of the lens grooves 221b of the linear Fresnel lens portion 22b and the positions of the bottoms 222b of the lens grooves 221b. The heater wire 5b in the third embodiment is routed on the front surface 23b of the base 2b, which is the surface opposite to the radar device 10, and the straight portions 51b of the heater wire 5b routed in a meandering manner on the front surface 23b of the base 2b are routed so as to follow the extension direction of the lens grooves 221b of the linear Fresnel lens portion 22b and the positions of the bottoms 222b of the lens grooves 221b.

[0041] In the third embodiment as well, when the 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 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.

[0042] According to the snow melting radome 1b of the third embodiment, it is possible to obtain the corresponding effects from the configuration corresponding to that of the first embodiment. Also, 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.

[0043] [Snow-melting radome of the fourth embodiment] A snow melting radome 1c according to the fourth embodiment of the present invention is also used, for example, as a bumper cover attached to a vehicle bumper, and includes an electromagnetic wave transparent base body 2c arranged in front of a radar device 10, as shown in Figures 7 and 8. The base body 2c 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 base body 1c 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.

[0044] A linear Fresnel lens portion 22c is formed as a Fresnel lens portion in the electromagnetic wave irradiation region R of the back surface 21c of the base 2c facing the radar device 10, and the lens grooves 221c of the linear Fresnel lens portion 22c are arranged to extend in a substantially horizontal direction. The substantially horizontal direction in which the lens grooves 221c extend preferably has an inclination angle of 5° or less with respect to the horizontal direction, and more preferably 3° or less. The linear Fresnel lens portion 22c and the front surface 23c of the base 2c are formed to perform refraction similar to that of the linear Fresnel lens portion 22 and the front surface 23 in the first embodiment.

[0045] The snow melting radome 1c of the fourth embodiment has an electromagnetic wave transparent back substrate 8c, which is laminated on the radar device 10 side of the base 2c and is in close contact with the base 2c and fixed by welding, adhesive, etc. A protrusion 81c extending in a substantially horizontal direction is formed on the front side of the back substrate 2c, and the protrusion 81c is arranged so as to mesh with the lens groove 221c, and the back substrate 8c is fixed to the back side of the base 2c.

[0046] The rear substrate 8c is formed of, for example, an insulating, electromagnetic wave-transmitting synthetic resin, and can be formed using a synthetic resin of a different or the same type as either or both of the first resin substrate 3 and the second resin substrate 4 in the first embodiment. Similar to the relationship between the first resin substrate 3 and the second resin substrate 4 in the first embodiment, it is preferable from the viewpoint of improving the electromagnetic wave transmission performance to form the rear substrate 8c from a material whose refractive index n, defined based on the complex dielectric constant, matches or is approximately the same as or close to that of the base 2c, and it is preferable that the difference in refractive index between the rear substrate 8c and the base 2c is within a range of 0 to 10%.

[0047] Furthermore, the back substrate 8c in the illustrated example is an integrally molded product formed by injection molding or the like using the same material as the first resin substrate 3 or the second resin substrate 4 in the first embodiment, but it may also be formed by stacking the first resin substrate 3 and the second resin substrate 4, etc., and fixing them to each other by welding or the like.

[0048] A heater wire 5c is wired on a back surface 82c, which is the surface of the back surface base material 8c facing the radar device 10, and is wired in a predetermined pattern in the surface direction of the back surface base material 8c so as to exhibit a snow melting function in the electromagnetic wave transmission region R. The conductive material and shape of the heater wire 5c are the same as those of the heater wire 5 in the first embodiment.

[0049] The heater wire 5c in the fourth embodiment is also routed in a serpentine manner to have straight portions 51c and folded portions 52c, and the heater wire 5c is routed so as to approximately follow the extension direction of the lens grooves 221c of the linear Fresnel lens portion 22c and the positions of the bottoms 222c of the lens grooves 221c. More specifically, the straight portions 51c of the heater wire 5c routed in a serpentine manner on the back surface 82c of the back substrate 8c are routed so as to follow the extension direction of the lens grooves 221c of the linear Fresnel lens portion 22c and the positions of the bottoms 222c of the lens grooves 221c.

[0050] Note that instead of wiring the heater wire 5c on the back surface 82c, which is the surface of the back surface base material 8c facing the radar device 10, a configuration in which the heater wire 5c is embedded in this back surface base material 8c may be used, for example, by stacking a first resin base material 3 and a second resin base material 4 and bonding them together by welding or the like to form the back surface base material 8c. Even when the heater wire 5c is embedded in the back surface base material 8c, the heater wire 5c may be wired in the same wiring pattern as when the heater wire 5c is wired on the back surface 82c of the back surface base material 8c, and the heater wire 5c may be wired so as to approximately follow the extension direction of the lens grooves 221c of the linear Fresnel lens portion 22c and the position of the bottoms 222c of the lens grooves 221c.

[0051] In the fourth embodiment as well, when the radar device 10 irradiates linearly polarized electromagnetic waves, it is preferable from the viewpoint of improving electromagnetic wave transmittance to arrange the straight portion 51c of the meandering wiring of the heater wire 5c so as to extend in a direction approximately perpendicular to the polarization plane of the linearly polarized electromagnetic waves irradiated by the radar device 10. Moreover, both ends of the continuously extending heater wire 5c in the fourth embodiment are also connected to the wire harness 7c at connection portions 6c, respectively, in the region outside the electromagnetic wave irradiation region R of the base 2c, so that a current is supplied to the heater wire 5c via the wire harness 7c.

[0052] The snow melting radome 1c of the fourth embodiment can achieve the same effects as those of the first embodiment through the same configuration. Furthermore, for example, when the outer surface of the base 2c is to be a decorative surface, it is possible to eliminate the irregularities on the outer surface of the base 2c caused by the installation of the heater wire 5c and ensure smoothness.

[0053] Furthermore, when wiring the heater wire 5c on the back surface 82c, which is the surface of the back substrate 8c facing the radar device 10, the desired wiring shape of the heater wire 5c can be achieved more easily than when directly installing it on the bottom 222c of the lens groove 221c.

[0054] Furthermore, when the heater wire 5c is embedded in the back base material 8c, the desired wiring shape of the heater wire 5c and the desired heat conduction to the base 2c can be stably achieved. Furthermore, the back base material 8c provided around the heater wire 5c can ensure the waterproofness and weather resistance of the heater wire 5c.

[0055] [Snow-melting radome of the fifth embodiment] A snow melting radome 1d according to the fifth embodiment of the present invention is also used, for example, as a bumper cover attached to a vehicle bumper, and includes an electromagnetic wave transparent base body 2d arranged in front of a radar device 10, as shown in Figures 9 and 10. The base body 2d is made up of a first resin base material 3d and a second resin base material 4d similar to the first resin base material 3 and the second resin base material 4 in the first embodiment, and is configured by stacking the first resin base material 3d and the second resin base material 4d and fixing them to each other by welding or the like.

[0056] In the electromagnetic wave irradiation area R on the radar device 10 side surface of the first resin base material 3d, which corresponds to the electromagnetic wave irradiation area R on the radar device 10 side back surface 21d of the base 2d, a circular Fresnel lens portion 24d having concentric lens grooves 241d is formed as a Fresnel lens portion.

[0057] The circular Fresnel lens portion 24d is formed so as to refract the electromagnetic waves irradiated from the radar device 10 arranged behind the base 2d so as to narrow the radiation width in the vertical direction, etc. when they are emitted from the front surface 23d of the base 2d, and to refract the reflected waves incident on the front surface 23d of the base 2d so as to converge in the vertical direction, etc. towards the radar device 10 when they are emitted from the back surface 21d of the base 2d or the circular Fresnel lens portion 24d.

[0058] A heater wire 5d is wired in the electromagnetic wave irradiation region R of the base 2d, and the heater wire 5d is wired in a predetermined pattern in the surface direction of the electromagnetic wave permeable base 2d so as to exert a snow melting function in the electromagnetic wave permeable region R. The conductive material and shape of the heater wire 5d are the same as those of the heater wire 5 in the first embodiment.

[0059] The heater wire 5d in the fifth embodiment is embedded in the base 2d, and is embedded between the first resin base material 3d and the second resin base material 4d. The heater wire 5d in the fifth embodiment is routed so as to substantially follow the extending direction of the lens grooves 241d of the circular Fresnel lens portion 24d and the positions of the bottoms 242d of the lens grooves 241d, and so that a part of the heater wire 5d is bridged between the concentric lens grooves 241d when viewed from the front or rear of the radome.

[0060] In the fifth embodiment, both ends of the continuously extending heater wire 5d are also connected to the wire harness 7d at connection parts 6d in the outer region of the electromagnetic wave irradiation region R of the base 2d, so that current is supplied to the heater wire 5d via the wire harness 7d.

[0061] In the fifth embodiment, the heater wire 5d is routed so as to substantially follow the extending direction of the lens grooves 241d of the circular Fresnel lens portion 24d and the positions of the bottoms 242d of the lens grooves 241d, and part of the heater wire 5d is routed between the concentric lens grooves 241d when viewed from the front of the radome. However, the heater wire 5d may be routed on the back surface 21d of the base 2d as in the second embodiment, if necessary, by forming the base 2d as an integrally molded product of the first resin base material 3d or the second resin base material 4d. The wiring configuration in the fourth embodiment may also be routed on the front surface 23d of the base 2d as in the third embodiment, or on a back surface base material that is in close contact with the base 2d as in the fourth embodiment.

[0062] The snow melting radome 1d of the fifth embodiment can achieve the same effects as those of the first embodiment through a configuration corresponding to that of the first embodiment. Also, even when the Fresnel lens portion is a circular Fresnel lens portion 24d, the desired snow melting function can be achieved by effectively utilizing the portions of the base 2d that do not contribute or have a low contribution to the detection of the radar device 10, while minimizing the attenuation of the electromagnetic waves and reflected waves emitted by the radar device 10 due to the installation of the heater wire 5d.

[0063] [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.

[0064] For example, in the first to fourth embodiments, the heater wires 5, 5a, 5b, and 5c are wired in a serpentine manner, but the wiring shape or wiring pattern of the heater wires in the snow melting radome having a linear Fresnel lens portion of the present invention may be any appropriate shape or pattern within the scope of the present invention and is not limited to serpentine wiring. Furthermore, in the snow melting radome of the present invention, when the heater wires are 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 wires so as to extend in a direction approximately parallel to the polarization plane of the linearly polarized electromagnetic wave irradiated by the radar device.

[0065] Furthermore, the snow melting radome of the present invention is suitable for use as a radome for an in-vehicle radar device, but the snow melting radome of the present invention also includes radomes other than those for in-vehicle radar devices. [Industrial Applicability]

[0066] The present invention can be used, for example, in a radome for an on-vehicle radar device that is disposed in front of the on-vehicle radar device. [Explanation of symbols]

[0067] 1, 1a, 1b, 1c, 1d... Snow melting radome 2, 2a, 2b, 2c, 2d... Base 21, 21a, 21b, 21c, 21d... Rear surface 22, 22a, 22b, 22c... Linear Fresnel lens section 221, 221a, 221b, 221c... Lens groove 222, 222a, 222b, 222c... Bottom portion 23, 23a, 23b, 23c, 23d... Front surface 24d... Circular Fresnel lens section 241d... Lens groove 242d... Bottom portion 3, 3d... First resin base material 4, 4d... Second resin base material 5, 5a, 5b, 5c, 5d... Heater wire 51, 51a, 51b, 51c... Straight portion 52, 52a, 52b, 52c... Folded portion 6, 6a, 6b, 6c, 6d... Connection portion 7, 7a, 7b, 7c, 7d... Wire harness 8c... Rear substrate 81c... Protrusion 82c... Rear surface 10... On-vehicle radar device R... Electromagnetic wave irradiation area

Claims

1. an electromagnetic wave transparent substrate disposed in front of the radar device; a Fresnel lens portion is formed in an electromagnetic wave irradiation area on the surface of the base body facing the radar device; A snow melting radome characterized in that a heater wire is laid out so as to substantially follow the direction in which the lens grooves of the Fresnel lens portion extend and the position of the bottom of the lens grooves.

2. the Fresnel lens portion is a linear Fresnel lens portion, It is located in front of the vehicle radar device, 2. The snow melting radome according to claim 1, wherein the lens grooves of the linear Fresnel lens portion are arranged to extend in a substantially horizontal direction.

3. 3. The snow melting radome according to claim 1, wherein the heater wire is embedded in the base body.

4. 3. The snow melting radome according to claim 1, wherein the heater wire is arranged so as to be disposed at the bottom of the lens groove.

5. 3. The snow melting radome according to claim 1, wherein the heater wire is wired on a surface of the base opposite to the radar device.

6. an electromagnetic wave transparent back substrate is laminated on the radar device side of the base and is in close contact with the base; The protrusions on the rear substrate are arranged to engage with the lens grooves, 3. The snow melting radome according to claim 1, wherein the heater wire is wired on the surface of the back base material facing the radar device.

7. an electromagnetic wave transparent back substrate is laminated on the radar device side of the base and is in close contact with the base; The protrusions on the rear substrate are arranged to engage with the lens grooves, 3. The snow melting radome according to claim 1, wherein the heater wire is embedded in the back substrate.

8. the Fresnel lens portion is a circular Fresnel lens portion, 2. The snow melting radome according to claim 1, wherein a part of said heater wire is wired so as to be bridged between said concentric lens grooves when viewed from the front of the radome.

Images