Electromagnetic wave permeable cover

Abstract

To provide a technology that can suppress the localized concentration of heat in the main body of an electromagnetic wave-transmitting cover. [Solution] The heater wires 50 of the electromagnetic wave-transmitting cover 3 are configured such that, at the general contact portion 51s of the connection ends 51, the distance between the outermost connection end 51 in the arrangement direction and the adjacent connection end 51 is greater than the distance between the two central connection ends 51 in the arrangement direction. Alternatively, the heater wires 50 of the electromagnetic wave-transmitting cover 3 are configured such that, at the general contact portion 51s of the connection ends 51, the electrical resistance of the outermost connection ends 51 on both sides in the arrangement direction is less than the electrical resistance of the two central connection ends 51 in the arrangement direction.

Description

Technical Field

[0001] The present invention relates to an electromagnetic wave transmission cover disposed outside an electromagnetic wave radar.

Background Art

[0002] In recent years, the development of vehicle driving assistance systems has been actively carried out, and various electromagnetic wave radars used in the driving system are attached to vehicles.

[0003] As one type of the above electromagnetic wave radar, millimeter wave radar, laser radar, etc. are known. This type of electromagnetic wave radar is used for the A.C.C (Adaptive Cruise control) of a vehicle.

[0004] A.C.C. measures driving information such as the inter-vehicle distance and relative speed between the vehicle ahead and the host vehicle by means of a sensor mounted on the front side of the vehicle, and based on this driving information, controls the throttle and brakes to accelerate or decelerate the host vehicle and control the inter-vehicle distance. In recent years, A.C.C. has been attracting attention as one of the core technologies of an advanced road traffic system (ITS) aiming at alleviating traffic congestion and reducing accidents. A millimeter wave radar, which is a type of electromagnetic wave radar, transmits millimeter waves with a frequency of 30 GHz to 300 GHz and a wavelength of 1 to 10 mm, and receives the millimeter waves reflected by an object. The inter-vehicle distance and relative speed between the vehicle ahead and the host vehicle can be calculated from the difference between the transmitted wave and the received wave.

[0005] Also, as another electromagnetic wave radar, LiDAR (Light Detection and Ranging) is known. LiDAR is a remote sensing technology using light and is used in a driving assistance system. In LiDAR, light with a relatively short wavelength is emitted toward an object using a laser, and the light reflected by the object is detected. Among LiDARs, those that perform sensing using near-infrared light are advantageous for detecting relatively short-range obstacles.

[0006] The emission and detection units of the various electromagnetic wave radars described above are mounted on the outermost parts of the vehicle (i.e., the front end, side end, rear end, etc.). Since the vehicle's design would be compromised if these emission and detection units were visible from outside the vehicle, it is common practice to provide an electromagnetic wave-transmitting cover further outside the emission and detection units that covers them while allowing the target electromagnetic waves to pass through. In this specification, a device comprising an electromagnetic wave-transmitting cover and an electromagnetic wave radar will be referred to as an electromagnetic wave radar unit, as necessary.

[0007] The electromagnetic wave-transmitting cover described above is the part of the electromagnetic wave radar unit that is exposed to the outside of the vehicle, and is positioned on the outside of the electromagnetic wave radar, in other words, on the side of the electromagnetic wave emission direction of the emission part relative to the electromagnetic wave radar. It can also be said that the electromagnetic wave-transmitting cover is positioned on the electromagnetic wave path of the electromagnetic wave radar.

[0008] Because the electromagnetic wave-transmitting cover is exposed to the outside of the vehicle, it may become covered in frost in cold weather or snow during snowfall. If the electromagnetic wave-transmitting cover is covered in frost or snow, the sensing function of the electromagnetic wave radar located on its back side, i.e., the inner side, and the communication function of the communication device in that electromagnetic wave radar may be impaired.

[0009] Patent Document 1 describes an invention relating to an electromagnetic wave-transparent cover for covering a millimeter-wave radar, a type of electromagnetic wave radar. The electromagnetic wave-transparent cover described in Patent Document 1 is installed on the path of millimeter waves transmitted and received by the millimeter-wave radar (sensor 2) and comprises a resin cover body (base material 7, decorative layer 8, transparent layer 9) and a heater part (heater sheet 6) integrated with the cover body. With this type of electromagnetic wave-transparent cover, the heater wires 11 and 12 of the heater part generate heat when energized, making it possible to melt frost and snow covering the electromagnetic wave-transparent cover. Furthermore, it is believed that this can suppress interference with the sensing function and communication function of the electromagnetic wave radar caused by frost and snow. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2023-46849 [Overview of the project] [Problems that the invention aims to solve]

[0011] As described above, by providing a heater unit in the electromagnetic wave-transmitting cover, it is possible to melt the frost and snow covering the electromagnetic wave-transmitting cover. However, on the other hand, conventional electromagnetic wave-transmitting covers equipped with a heater were sometimes less durable than electromagnetic wave-transmitting covers without a heater. Specifically, in conventional electromagnetic wave-transmitting covers equipped with a heater, heat generation sometimes concentrated in the part of the cover body located near the connection end of the heater wire. If the amount of heat generated in that part was excessive, it could interfere with the use of the cover as an electromagnetic wave-transmitting cover.

[0012] This invention has been made in view of the above circumstances, and aims to provide a technology that can suppress the concentration of localized heat in the cover body of an electromagnetic wave-transmitting cover. [Means for solving the problem]

[0013] A first embodiment of the present invention, which solves the above problems, is an electromagnetic wave-transmitting cover, An electromagnetic wave transparent cover that is placed on the outside of an electromagnetic wave radar, It comprises a cover body made of a plate-shaped, electromagnetically transparent resin material, and a heater part having two heater wires and integrally provided with the cover body, Each of the aforementioned heater wires has connecting ends at both ends and a general heater portion which is the remaining portion and connects the two aforementioned connecting ends. The aforementioned connection end is the end of the electromagnetic wave-transmitting cover and is arranged in parallel with the connection region that extends outward. Each of the aforementioned connecting ends includes a general connecting portion continuous with the general heater portion, and a crossing extension portion continuous with the general connecting portion and extending in a direction intersecting the general connecting portion. In the general connection section, the electromagnetic wave-transmitting cover is such that the distance between the outermost connection end in the arrangement direction and the adjacent connection end is wider than the distance between the two central connection ends in the arrangement direction.

[0014] A second embodiment of the present invention, which solves the above problems, provides an electromagnetic wave-transmitting cover, An electromagnetic wave transparent cover that is placed on the outside of an electromagnetic wave radar, It comprises a cover body made of a plate-shaped, electromagnetically transparent resin material, and a heater part having two heater wires and integrally provided with the cover body, Each of the aforementioned heater wires has connecting ends at both ends and a general heater portion which is the remaining portion and connects the two aforementioned connecting ends. The aforementioned connection end is the end of the electromagnetic wave-transmitting cover and is arranged in parallel with the connection region that extends outward. Each of the aforementioned connecting ends includes a general connecting portion continuous with the general heater portion, and a crossing extension portion continuous with the general connecting portion and extending in a direction intersecting the general connecting portion. In the general connection section, the electromagnetic wave-transmitting cover is such that the electrical resistance of the connection ends at the outermost ends on both sides in the arrangement direction is smaller than the electrical resistance of the two connection ends in the center in the arrangement direction. [Effects of the Invention]

[0015] According to the technology of the present invention, it is possible to suppress the concentration of localized heat in the cover body portion of an electromagnetic wave-transmitting cover. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram illustrating the external view of the electromagnetic wave radar unit of Example 1, which has an electromagnetic wave-transmitting cover. [Figure 2] This is an explanatory diagram illustrating the positional relationship between the cover body and the heater part in the electromagnetic wave-transmitting cover of Example 1. [Figure 3] The explanatory drawing schematically illustrates a state in which the electromagnetic wave transmission cover of Example 1 is cut in the thickness direction. [Figure 4] The explanatory drawing schematically illustrates a connection region and a connection end portion in the electromagnetic wave transmission cover of Example 1. [Figure 5] The explanatory drawing schematically illustrates a positional relationship between a cover main body portion and a heater portion in the electromagnetic wave transmission cover of the comparative example. [Figure 6] The explanatory drawing schematically illustrates a state in which the electromagnetic wave transmission cover of the comparative example is cut in the thickness direction. [Figure 7] The explanatory drawing schematically illustrates a connection region and a connection end portion in the electromagnetic wave transmission cover of the comparative example.

Mode for Carrying Out the Invention

[0017] The inventor of the present invention has intensively studied to suppress the concentration of partial heat generation in the electromagnetic wave transmission cover described above. The inventor has focused on the fact that the concentration of partial heat generation in the electromagnetic wave transmission cover described above is likely to occur in the connection region of the electromagnetic wave transmission cover.

[0018] The connection region of the electromagnetic wave transmission cover is an end portion of the electromagnetic wave transmission cover and is a portion that extends outward from the electromagnetic wave transmission cover. In the connection region of the electromagnetic wave transmission cover, connection end portions that are both ends of the heater wire are arranged in parallel. The inventor has speculated that the concentration of partial heat generation in the electromagnetic wave transmission cover is derived from the connection end portions of the heater wire.

[0019] The heater wire has two connection end portions that are both ends, and a general heater portion that connects the two connection end portions. The general heater portion is a portion of the heater wire that bears the heating function, and the connection end portion is a portion of the heater wire that is electrically connected to other element devices such as a power source and a control device.

[0020] The heating region of the electromagnetic wave-transmitting cover is where the general heater portion of the heater wire is located. On the other hand, the connection end of the heater wire is located in the connection region of the electromagnetic wave-transmitting cover.

[0021] The heating region is the main area of ​​the electromagnetic wave-transmitting cover. The general heater section of the heater wire, which is placed in this heating region, is responsible for generating heat when power is supplied and thereby heating the heating region. In order to heat the entire heating region uniformly, the general heater section is generally folded at approximately equal intervals and arranged approximately evenly throughout the entire heating region.

[0022] On the other hand, the connection region is a secondary region of the electromagnetic wave-transmitting cover. The connection ends of the heater wires, which are located in this connection region, are connected to the element device described above and serve to electrically connect the element device and the heater unit by wire. The connection region is located at the end of the electromagnetic wave-transmitting cover and extends outward from the electromagnetic wave-transmitting cover. The connection ends of the heater wires are gathered in this connection region and arranged in parallel within this connection region.

[0023] Incidentally, in order to make the electromagnetic wave-transmitting cover more compact, the connection area in the electromagnetic wave-transmitting cover is usually narrower than the heating area. For this reason, the connection ends are positioned close to each other in the connection area. If there are many heater wires, the number of connection ends placed in the connection area also increases, and adjacent connection ends in the connection area become even closer together.

[0024] The inventor conceived the idea that when an electromagnetic wave-transmitting cover has two or more heater wires, the adjacent connection ends are too close together, causing the temperature of the connection ends of the heater wires to become excessively high, resulting in the aforementioned concentration of localized heat generation. Based on this idea, the inventor aimed to suppress excessive temperature rise in the heater wire at the connection end.

[0025] The electromagnetic wave-transmitting cover of the first aspect of the present invention suppresses excessive temperature rise of the heater wire at the connection ends by arranging adjacent connection ends at appropriate intervals.

[0026] Generally, the connection end of the heater section in an electromagnetic wave-transmitting cover extends inward beyond the electromagnetic wave-transmitting cover. This is because the element device connected to this connection end is generally positioned inside the electromagnetic wave-transmitting cover, in other words, behind the electromagnetic wave emission device included in the electromagnetic wave radar.

[0027] More specifically, the general connection portion, which is the part of the connection end that faces the general heater section, extends continuously with the general heater section. The remaining portion of the connection end, the cross extension portion, is continuous with the general connection portion and extends in a direction that intersects with the general connection portion. Therefore, the connection end can be said to have a bent shape. The cross extension portion is the part of the connection end that is actually connected to the power supply or other elemental device.

[0028] The inventors of this invention focused particularly on the general connecting portion P1, the cross-extended portion P3, and the boundary portion (bend initiation portion) P2 between the cross-extended portion and the general connecting portion P1, among the bent connecting ends, and measured the temperature of each portion. The positions of P1-P3 correspond to the positions of each portion shown in Figure 6.

[0029] As a result, the inventor found that the temperature of each part was P1 > P2 > P3, and that heat generation was particularly concentrated in the general connection section. Based on this, the inventor aimed to suppress the localized concentration of heat generation in the electromagnetic wave-transmitting cover by reviewing the configuration of the connection end in the general connection section.

[0030] In the electromagnetic wave-transmitting cover of the first embodiment, adjacent connection ends are arranged at an appropriate interval in the general connection section. More specifically, in the general connection section, the distance between the connection end at the outermost end in the arrangement direction and the adjacent connection end is made wider than the distance between the two central connection ends in the arrangement direction.

[0031] As a result, the electromagnetic wave-transmitting cover of the first embodiment can suppress excessive temperature rise of the heater wire at the connection end. As will be explained in the section on embodiments later, the electromagnetic wave-transmitting cover was actually able to suppress localized heat concentration in the electromagnetic wave-transmitting cover.

[0032] In the electromagnetic wave-transmitting cover of the second aspect of the present invention, in the general connection section described above, the electrical resistance of some of the connection ends is made lower than that of other parts, thereby suppressing an excessive temperature rise of the heater wire at the connection ends.

[0033] More specifically, in the electromagnetic wave-transmitting cover of the second embodiment, in the general connection section, the electrical resistance of the connection ends at the outermost ends on both sides in the arrangement direction is made smaller than the electrical resistance of the two connection ends in the center in the arrangement direction, out of the four connection ends of the two heater wires.

[0034] This makes it possible to suppress excessive temperature rise of the heater wire at the connection end, even with the electromagnetic wave-transmitting cover of the second embodiment.

[0035] The electromagnetic wave-transmitting cover of the present invention will be described below for each of its components.

[0036] Unless otherwise specified, the numerical range "x~y" described herein includes a lower limit x and an upper limit y. Furthermore, a numerical range can be constructed by arbitrarily combining these upper and lower limits, as well as the numerical values ​​listed in the embodiments. Additionally, any numerical values ​​arbitrarily selected from within the numerical range can be used as the upper and lower limits.

[0037] In this specification, the electromagnetic wave radar unit of the first embodiment means a unit comprising an electromagnetic wave radar and an electromagnetic wave-transmitting cover according to the first embodiment of the present invention. The electromagnetic wave radar unit of the second embodiment means a unit comprising an electromagnetic wave radar and an electromagnetic wave-transmitting cover according to the second embodiment of the present invention.

[0038] In this specification, unless otherwise specified, the description of the electromagnetic wave-transparent cover in the electromagnetic wave radar unit of the first embodiment shall also serve as the description of the electromagnetic wave-transparent cover in the first embodiment, and the description of the electromagnetic wave-transparent cover in the first embodiment shall also serve as the description of the electromagnetic wave-transparent cover in the electromagnetic wave radar unit of the first embodiment. Similarly, the description of the electromagnetic wave-transparent cover in the electromagnetic wave radar unit of the second embodiment shall also serve as the description of the electromagnetic wave-transparent cover in the second embodiment, and the description of the electromagnetic wave-transparent cover in the second embodiment shall also serve as the description of the electromagnetic wave-transparent cover in the electromagnetic wave radar unit of the second embodiment.

[0039] Furthermore, in this specification, when the term "electromagnetic wave radar unit" is used without further explanation, it refers collectively to the electromagnetic wave radar unit of the first embodiment and the electromagnetic wave radar unit of the second embodiment. When the term "electromagnetic wave transparent cover" is used without further explanation, it refers collectively to the electromagnetic wave transparent cover of the first embodiment of the present invention and the electromagnetic wave transparent cover of the second embodiment of the present invention.

[0040] As described above, the electromagnetic wave radar in the electromagnetic wave radar unit can preferably be a millimeter-wave radar, laser radar, LiDAR, etc., but is not limited to these.

[0041] The electromagnetic wave-transmitting cover of the present invention comprises a cover body made of a plate-shaped resin material that is electromagnetic wave-transmitting, and a heater part having two heater wires and integrally provided with the cover body.

[0042] The electromagnetic wave-transmitting cover of the present invention is positioned on the outside of an electromagnetic wave radar, in other words, on the side of the electromagnetic wave emission device included in the electromagnetic wave radar that is in the emission direction. Such an electromagnetic wave-transmitting cover is required to have electromagnetic wave transmission performance. The heater portion of the electromagnetic wave-transmitting cover has heater wires, and it is difficult to expect excellent electromagnetic wave transmission performance from these heater wires. Therefore, the electromagnetic wave transmission performance in the electromagnetic wave-transmitting cover of the present invention is mainly provided by the cover body.

[0043] The main body of the cover is made of a resin material and should be plate-shaped and transparent to electromagnetic waves. However, the region of the main body of the cover that is located on the side of the electromagnetic wave emission device in the electromagnetic wave radar that is in the direction of emission is preferably of uniform thickness.

[0044] The main body of the cover can be made of resin material. The resin material referred to here is any material whose main component is resin, and may contain various additives. Here, "main component" means that when the total resin material is considered to be 100% by mass, the proportion of resin is 90% by mass or more.

[0045] For the main body of the cover, it is preferable to select at least one resin from polycarbonate (PC), acrylic resin, polypropylene (PP), acrylonitrile-ethylene propylene diene rubber-styrene copolymer resin (AES), etc.

[0046] Furthermore, it is preferable to select a resin for the cover body that is resistant to deformation even when the heater wires heat up. From this perspective, it is preferable to select a resin for the cover body that has a relatively high glass transition temperature. Specifically, it is preferable to select a resin for the cover body that has a glass transition temperature of 120°C or higher, 115°C or higher, or 110°C or higher. There is no particular upper limit to the glass transition temperature of the resin used for the cover body, but it is preferable to use one with a glass transition temperature of 140°C or lower, for example.

[0047] The main body of the cover may have a single-layer structure or a multi-layer structure. If the cover body has a multilayer structure, for example, the cover body may have a base layer made of resin material on which a design layer capable of displaying various designs is formed by painting, printing, metal deposition, etc., or a coating layer may be formed on the design layer.

[0048] The base material in the main body of the cover may also be a single-layer structure or a multilayer structure of two or more layers. If the base material is a multilayer structure, each layer may be made of the same material or different materials.

[0049] The heater section has two heater wires and is integrally mounted on the cover body mentioned above. The heater section only needs to have two heater wires, and of course, it may have three or more heater wires. The heater wires only need to generate heat when powered, and their material is not particularly limited, but it is preferable to select a metal with a high resistivity, such as an alloy containing nickel and chromium (nichrome) or stainless steel.

[0050] The method for forming the heater wire is also not particularly limited. For example, the heater wire may be formed by shaping the above-mentioned metal or alloy into a wire and integrating it with the cover body by methods such as bonding, welding, or insert molding. Alternatively, the heater wire may be formed by printing a composite material of these metal powders and resin onto the cover body.

[0051] The heater wire has two connection ends at both ends and a portion between these two connection ends. The connection ends are arranged in parallel within the connection region of the electromagnetic wave-transmitting cover. As previously described, these connection ends are connected to the element device and are responsible for electrically connecting the element device and the heater section via a wire.

[0052] The portion of the heater wire between the two connection ends, or in other words, the portion connecting the two connection ends, is located in the heating region, which is the main area of ​​the electromagnetic wave-transmitting cover, and is responsible for heating the heating region. This portion of the heater wire is referred to as the general heater section.

[0053] For functional reasons, the connection area of ​​the electromagnetic wave-transparent cover where each connection point of each heater wire is located should be smaller than the heating area of ​​the electromagnetic wave-transparent cover where the general heater portion of each heater wire is located. Specifically, when the projected area of ​​the heating region in the electromagnetic wave-transmitting cover is set to 100 area%, the projected area of ​​the connection region in the electromagnetic wave-transmitting cover is preferably 20 area% or less, 15 area% or less, or 10 area% or less. Here, "projected area" refers to the projected area when each part of the electromagnetic wave-transmitting cover is projected in the direction of its thickness.

[0054] The connection region is located at the end of the electromagnetic wave-transmitting cover and extends outward from the cover. Preferably, such a connection region is in the shape of a strip with its longitudinal direction oriented in the direction of extension. The extension direction of the connection area can be any direction that extends outward from the electromagnetic wave-transmitting cover, and can be appropriately set according to the positional relationship between the electromagnetic wave-transmitting cover and the device. For example, the connection area may extend radially outward from the electromagnetic wave-transmitting cover, or it may extend to the back side of the electromagnetic wave-transmitting cover.

[0055] The general heater section should be arranged approximately evenly across the entire heating area of ​​the electromagnetic wave-transmitting cover. For example, it may be folded multiple times in a zigzag pattern or wound in a spiral pattern. In either case, the connection ends of the heater wires are gathered in the connection area, so the portion of the general heater section of the heater wire that is on the connection end side is positioned near the connection area.

[0056] Each connection point of each heater wire may be arranged in parallel within the connection area, and may be arranged parallel to each other, or some or all of them may not be arranged parallel to each other, but it is preferable that they be arranged parallel to each other in general connection points.

[0057] As previously described, the connection section has a bent shape, comprising a general connecting section that is continuous with the general heater section, and a crossing extension section that is continuous with the general connecting section and extends in a direction intersecting the general connecting section. The intersecting extension may extend in a straight line, or it may extend in a straight line and bend in two or more stages, or it may extend in a curved shape. The intersection angle θ of the cross extension portion with respect to the general connection portion is not particularly limited, but the smaller the intersection angle θ, the more pronounced the effect of the electromagnetic wave-transmitting cover of the present invention. In view of this, the intersection angle θ is particularly preferably within the range of 0° < θ < 150°, 0° < θ < 120°, or 0° < θ < 100°. Furthermore, the intersection angle θ of the crossing extension to the general connecting section may simply be the intersection angle between the general connecting section and the crossing extension section, or it may be the intersection angle between the tangent to the general connecting section and the tangent to the crossing extension section.

[0058] In the electromagnetic wave-transmitting cover of the first aspect of the present invention, in the general contact section, the distance between the outermost connection end in the arrangement direction and the adjacent connection end is wider than the distance between the two central connection ends in the arrangement direction.

[0059] For example, if the heater section has only two heater wires, four connection ends are arranged in parallel in the connection area. If these four connection ends are designated as the first connection end, second connection end, third connection end, and fourth connection end in order from the end in the direction of arrangement, then in the electromagnetic wave-transmitting cover of the first embodiment, the distance between the first connection end and the second connection end, and the distance between the third connection end and the fourth connection end are wider than the distance between the second connection end and the third connection end in the general contact area.

[0060] In this case, the distance between the first and second connection ends and the distance between the third and fourth connection ends may be the same or different.

[0061] Also, for example, when the heater section has three heater wires, six connection ends are arranged in parallel in the connection region. When the six connection ends are, in order from the end in the arrangement direction, the first connection end, the second connection end, the third connection end, the fourth connection end, the fifth connection end, and the sixth connection end, in the electromagnetic wave transmission cover of the first aspect, in the general connection section, it can be said that the distance between the first connection end and the second connection end and the distance between the fifth connection end and the sixth connection end are wider than the distance between the third connection end and the fourth connection end. In this case, the distance between the second connection end and the third connection end and the distance between the fourth connection end and the fifth connection end are not particularly limited, but it is preferable that they are wider than the distance between the third connection end and the fourth connection end, and it is particularly preferable that they are about the same as the distance between the first connection end and the second connection end and the distance between the fifth connection end and the sixth connection end.

[0062] In this case, the distance between the first connection end and the second connection end and the distance between the fifth connection end and the sixth connection end may be the same or different. Also, the distance between the second connection end and the third connection end and the distance between the fourth connection end and the fifth connection end may also be the same or different.

[0063] When the distance between the outermost end in the arrangement direction among the connection ends and the one adjacent to it is L1, and the two central distances in the arrangement direction are L2, the relationship between the distance L1 and the distance L2 only needs to be L1 > L2. For example, it is preferable that the relationship is 0.5×L1 < L2 < 0.95×L1, 0.6×L1 < L2 < 0.85×L1, or 0.65×L1 < L2 < 0.8×L1.

[0064] The specific size of the distance L2 is preferably in the range of 1.0 mm or more and less than 2 mm, 1.2 mm or more and 1.8 mm or less, or 1.3 mm or more and 1.6 mm or less. The specific size of the distance L1 is preferably 1.8 mm or more, 1.9 mm or more, or 2 mm or more. Although there is no upper limit to the preferable size of the distance L1, it is preferable that the distance L1 is 2.5 mm or less so that the outer shape of the electromagnetic wave transmission cover does not become overly large.

[0065] In the electromagnetic wave-transmitting cover of the second aspect of the present invention, in the general connection section, the electrical resistance of the connection ends at the outermost ends on both sides in the arrangement direction is smaller than the electrical resistance of the two connection ends in the center in the arrangement direction, among the four connection ends of the two heater wires.

[0066] For example, if the heater section has only two heater wires, four connection ends are arranged in parallel in the connection area. If these four connection ends are designated as the first connection end, second connection end, third connection end, and fourth connection end, in order from the end in the direction of arrangement, then in the electromagnetic wave-transmitting cover of the second embodiment, it can be said that the electrical resistance of the first and fourth connection ends in the general contact area is smaller than the electrical resistance of the second and third connection ends.

[0067] In this case, the electrical resistance of the first connection terminal and the electrical resistance of the fourth connection terminal may be the same or different. Also, the electrical resistance of the second connection terminal and the electrical resistance of the third connection terminal may be the same or different.

[0068] Furthermore, for example, if the heater section has three heater wires, six connection ends are arranged in parallel in the connection area. If these six connection ends are designated as the first connection end, second connection end, third connection end, fourth connection end, fifth connection end, and sixth connection end, in order from the end in the direction of arrangement, then in the electromagnetic wave-transmitting cover of the second embodiment, it can be said that the electrical resistance of the first connection end and the sixth connection end in the general contact section is smaller than the electrical resistance of the third connection end and the fourth connection end. In this case, the electrical resistance of the second and fifth connection ends is not particularly important, but it is preferable that it be smaller than the electrical resistance of the third and fourth connection ends, and particularly preferable that it be about the same as the electrical resistance of the first and sixth connection ends.

[0069] In this case, the electrical resistance of the first connection end and the electrical resistance of the sixth connection end may be the same or different. Also, the electrical resistance of the third connection end and the electrical resistance of the fourth connection end may be the same or different. Furthermore, the electrical resistance of the second connection end and the electrical resistance of the fifth connection end may also be the same or different.

[0070] If we denote the two electrical resistances at the outermost ends of the connection terminals in the direction of arrangement as Ω1, and the two electrical resistances in the center of the same arrangement direction as Ω2, then the relationship between electrical resistances Ω1 and Ω2 should be Ω1 < Ω2, but it is preferable that the relationship is, for example, 0.75 × Ω2 < Ω1 < 0.98 × Ω2, 0.80 × Ω2 < Ω1 < 0.95 × Ω2, or 0.85 × Ω2 < Ω1 < 0.93 × Ω2.

[0071] There are no particular limitations on the method for creating a difference in electrical resistance between Ω1 and Ω2 at the connection end; for example, one could choose to change the material or cross-sectional area of ​​the connection end. For example, if the amount of current flowing through the connection end is the same, a connection end with a smaller cross-sectional area will have a higher resistance than a connection end with a larger cross-sectional area.

[0072] For example, the electrical resistance of the general heater section may be the same as or different from the electrical resistance of the connection end. However, considering the heating function of the heater section, it is preferable that the electrical resistance of the general heater section be the same for each heater wire. In this case, the electrical resistance of the general heater section and the connection end on the same heater wire can be changed.

[0073] The electromagnetic wave-transmitting cover and electromagnetic wave radar unit of the present invention will be described below with specific examples.

[0074] (Example 1) Example 1 relates to an electromagnetic wave-transmitting cover and an electromagnetic wave radar unit according to a first embodiment. Figure 1 is a schematic diagram illustrating the external view of an electromagnetic wave radar unit having an electromagnetic wave transparent cover according to Example 1. Figure 2 is a schematic diagram illustrating the positional relationship between the cover body and the heater part in the electromagnetic wave transparent cover of Example 1. Figure 3 is a schematic diagram illustrating a cross-section of the electromagnetic wave transparent cover of Example 1 in the thickness direction. Figure 4 is a schematic diagram illustrating the connection area and connection end in the electromagnetic wave transparent cover of Example 1.

[0075] In the following examples, "top," "bottom," "left," "right," "front," and "rear" refer to the top, bottom, left, right, front, and rear in each respective figure. The front side is the forward side in the direction of vehicle travel, and the rear side is the rear side in the direction of vehicle travel.

[0076] As shown in Figure 1, the electromagnetic wave radar unit 1 of Embodiment 1 comprises an electromagnetic wave radar 2 and an electromagnetic wave transparent cover 3.

[0077] Electromagnetic wave radar 2 is a millimeter-wave radar for vehicles. Electromagnetic wave radar 2 is positioned at the front of the vehicle, specifically in the front area of ​​the engine compartment, and emits millimeter waves forward.

[0078] The electromagnetic wave-transmitting cover 3 is positioned in front of the electromagnetic wave radar 2. The electromagnetic wave-transmitting cover 3 is an emblem and is fixed to the vehicle's front grille (not shown in the diagram).

[0079] The electromagnetic wave-transmitting cover 3 comprises a cover body 4 and a heater 5. As shown in Figure 3, the main body of the cover 4 has a roughly three-layer structure in which a design layer 45 is formed on a base layer 40 that has a two-layer structure.

[0080] The rear layer 41 of the substrate layer 40, in other words, the rear layer located on the side of the electromagnetic wave radar 2, is made of AES and is roughly plate-shaped. The front layer 42 of the substrate layer 40, in other words, the front layer located on the side opposite to the electromagnetic wave radar 2, is made of PC and is roughly plate-shaped. Both AES and PC are resins with a glass transition temperature of 120°C to 140°C.

[0081] The outer shape of the front layer 42 and the outer shape of the rear layer 41 are roughly the same, and the front layer 42 and the rear layer 41 are integrally molded by the insert molding method described later.

[0082] As shown in Figure 2, the base layer 40 has a substantially elliptical portion and a substantially rectangular portion. The substantially elliptical portion and the substantially rectangular portion are composed of a front layer 42 and a rear layer 41. The rectangular portion extends radially outward and towards the rear from the peripheral edge of the elliptical portion.

[0083] The substantially elliptical portion of the substrate layer 40 forms the heating region 47 of the electromagnetic wave-transmitting cover 3 of Example 1. The substantially rectangular portion of the substrate layer 40 forms the connection region 48 of the electromagnetic wave-transmitting cover 3 of Example 1.

[0084] In the electromagnetic wave-transmitting cover 3 of Example 1, when the projected area of ​​the heating region 47 is set to 100 area%, the projected area of ​​the connection region 48 is approximately 5 area%.

[0085] As shown in Figures 1 and 3, the design layer 45 is positioned on the front side of the heating region 47. Specifically, the design layer 45 is printed on the front surface of the front layer 42 using an electromagnetic wave-transparent ink as the material.

[0086] As shown in Figure 2, the heater section 5 has two heater wires 50. Each heater wire 50 is formed by printing a composite material of copper powder and resin onto the cover body 4. Both ends of each heater wire 50 are connecting ends 51, and the remaining portion, the general heater section 52, connects the two connecting ends 51.

[0087] Of the heater wires 50, the general heater sections 52 are folded back at approximately equal intervals and are arranged approximately evenly throughout the entire heating region 47. The connection ends 51 of each heater wire 50 are gathered in a connection area 48 and arranged in parallel within that connection area 48.

[0088] In the electromagnetic wave-transmitting cover 3 of Example 1, each heater wire 50 is sandwiched between the front layer 42 and the rear layer 41 of the base layer 40 in the cover body 4. In the electromagnetic wave-transmitting cover 3 of Example 1, the heater wire 50 is printed on the rear surface of a pre-formed front layer 42. The base layer 40 of the cover body 4 is formed by an insert molding method, in which the front layer 42 on which the heater wire 50 is formed is used as an insert, and the rear layer 41 is formed on it. The cover body 4 is obtained by further printing a design layer 45 on the front surface of the base layer 40.

[0089] As shown in Figure 2, the heater section 5 in the electromagnetic wave-transmitting cover 3 of Embodiment 1 has two heater wires 50, and four connection ends 51 are arranged in parallel in the connection region 48. The connection ends 51 of each heater wire 50 are gathered in the connection region 48. The four connecting ends 51 are designated as the first connecting end 511, the second connecting end 512, the third connecting end 513, and the fourth connecting end 514, in order from the ends in the direction of arrangement, i.e., the left-right direction in Figure 2.

[0090] In the electromagnetic wave-transmitting cover 3 of Example 1, one of the two heater wires 50, the first heater wire 58, has one connection end 51 which is the first connection end 511, and the other connection end 51 which is the fourth connection end 514. Also, one of the two heater wires 50, the second heater wire 59, has one connection end 51 which is the second connection end 512, and the other connection end 51 which is the third connection end 513.

[0091] In the connection region 48, the first connection end 511, the second connection end 512, the third connection end 513, and the fourth connection end 514 extend in the longitudinal direction of the connection region 48. Of the first connection end 511, the second connection end 512, the third connection end 513, and the fourth connection end 514, the portion on the general heater section 52 side, in other words, the portion on the heating region 47 side, extends linearly. This linearly extending portion is the general connecting section 51s at each connection end 51.

[0092] The portion of the general connecting section 51s opposite to the general heater section 52 bends approximately twice, with the bending start section P2 shown in Figure 2 as the boundary, and extends in a direction intersecting the general connecting section 51s. This portion extending in a direction intersecting the general connecting section 51s is the intersecting extension section 51c at each connecting end 51. The general connection section 51s can also be described as the portion of the connection end 51 that is continuous with the general heater section 52. The cross extension section 51c can also be described as the portion that is connected to the element device (not shown in the figure).

[0093] The first connecting end 511 and the fourth connecting end 514 have a symmetrical shape in the direction of arrangement, and the second connecting end 512 and the third connecting end 513 also have a symmetrical shape in the direction of arrangement.

[0094] Each connecting end 51 extends parallel to each other in the general connecting section 51s. In the general connection section 51s, the distance between the first connecting end 511 and the second connecting end 512, and the distance between the third connecting end 513 and the fourth connecting end 514 are approximately 2 mm, while the distance between the second connecting end 512 and the third connecting end 513 is approximately 1.4 to 1.5 mm. Therefore, in the general connection section 51s, the distance between the first connecting end 511 and the second connecting end 512, and the distance between the third connecting end 513 and the fourth connecting end 514 are wider than the distance between the second connecting end 512 and the third connecting end 513.

[0095] In the electromagnetic wave-transmitting cover 3 of Example 1, the relationship between the distance L1 between the first connection end 511 and the second connection end 512, and the distance L1 between the third connection end 513 and the fourth connection end 514, and the distance L2 between the second connection end 512 and the third connection end 513 satisfies 0.7 × L1 ≤ L2 ≤ 0.75 × L1.

[0096] For reference, the general heater portions 52 of each heater wire 50 located in the heating region 47 are spaced at 1.6 mm or more apart from adjacent general heater portions 52, which is much wider than the spacing L1 mentioned above. Also, the intersection angle θ of the crossing extension portion 51c with respect to the general connecting portion 51s is within the range of 0° < θ < 150°.

[0097] (Comparative example) The electromagnetic wave-transmitting cover of the comparative example is substantially the same as the electromagnetic wave-transmitting cover of Example 1, except for the arrangement of the connection ends in the connection region. Figure 5 is a schematic diagram illustrating the positional relationship between the cover body and the heater portion in the comparative example's electromagnetic wave-transmitting cover. Figure 6 is a schematic diagram illustrating the cross-section of the comparative example's electromagnetic wave-transmitting cover in the thickness direction. Figure 7 is a schematic diagram illustrating the connection region and connection end in the comparative example's electromagnetic wave-transmitting cover. The following describes the electromagnetic wave-transmitting cover of the comparative example, focusing on the differences from the electromagnetic wave-transmitting cover of Example 1.

[0098] The electromagnetic wave-transmitting cover 3 of the comparative example differs significantly from the electromagnetic wave-transmitting cover 3 of Example 1 in terms of the spacing between adjacent connection ends 51.

[0099] As shown in Figure 5, in the comparative example electromagnetic wave-transmitting cover 3, each connection end 51 extends parallel to each other in the general contact section 51s. In the general contact section 51s, the distance between the first connection end 511 and the second connection end 512, the distance between the third connection end 513 and the fourth connection end 514, and the distance between the second connection end 512 and the third connection end 513 are all approximately 1.4 to 1.5 mm. Therefore, in the comparative example electromagnetic wave-transmitting cover 3, the distance between the first connection end 511 and the second connection end 512, and the distance between the third connection end 513 and the fourth connection end 514 in the general contact section 51s are approximately the same as the distance between the second connection end 512 and the third connection end 513.

[0100] In the comparative example, the electromagnetic wave-transmitting cover 3 showed that the electrical resistances of the first connection end 511 and the fourth connection end 514 in the general contact section 51s were greater than the electrical resistances of the second connection end 512 and the third connection end 513.

[0101] Specifically, in the straight section 51s, if the electrical resistance of the first connection end 511 and the fourth connection end 514 is Ω1, and the electrical resistance of the second connection end 512 and the third connection end 513 is Ω2, then Ω1 is approximately 1.1 × Ω2, and the relationship between the electrical resistances Ω1 and Ω2 is Ω1 > Ω2.

[0102] (Example 2) Example 2 relates to an electromagnetic wave-transmitting cover and an electromagnetic wave radar unit according to a second embodiment. The electromagnetic wave-transmitting cover of Example 2 is substantially the same as the electromagnetic wave-transmitting cover of the Comparative Example, except for the electrical resistance at the connection end. The electromagnetic wave-transmitting cover of Example 2 will be described below, focusing on the differences from the electromagnetic wave-transmitting cover of the comparative example.

[0103] In the electromagnetic wave-transmitting cover 3 of Example 2, each connection point extends parallel to the others in the general contact section 51s.

[0104] Furthermore, in the electromagnetic wave-transmitting cover 3 of Example 2, similar to the electromagnetic wave-transmitting cover 3 of the Comparative Example, the distance between the first connection end 511 and the second connection end 512, the distance between the third connection end 513 and the fourth connection end 514, and the distance between the second connection end 512 and the third connection end 513 in the general contact section 51s are all approximately 1.4 to 1.5 mm. Therefore, in the electromagnetic wave-transmitting cover 3 of Example 2, the distance between the first connection end 511 and the second connection end 512, and the distance between the third connection end 513 and the fourth connection end 514 in the general contact section 51s are approximately the same as the distance between the second connection end 512 and the third connection end 513.

[0105] However, the electromagnetic wave-transmitting cover 3 of Example 2 differs from the electromagnetic wave-transmitting cover 3 of the Comparative Example in terms of electrical resistance at each connection end 51. Specifically, the cross-sectional areas of the two connection ends 51 of the first heater wire 58, namely the first connection end 511 and the fourth connection end 514, are larger than the cross-sectional area of ​​the general heater section 52 of the first heater wire 58. In other words, the wire diameters of the first connection end 511 and the fourth connection end 514 of the first heater wire 58 are thicker than the wire diameter of the general heater section 52 of the first heater wire 58. On the other hand, the diameter of the second heater wire 59 is approximately constant along its entire length and is roughly the same as the diameter of the general heater section 52 in the first heater wire 58.

[0106] Therefore, in the electromagnetic wave-transmitting cover 3 of Example 2, the electrical resistance of the first connection end 511 and the fourth connection end 514 in the general contact section 51s is smaller than the electrical resistance of the second connection end 512 and the third connection end 513. Specifically, in the general connection section 51s, if the electrical resistance of the first connection end 511 and the fourth connection end 514 is Ω1, and the electrical resistance of the second connection end 512 and the third connection end 513 is Ω2, then Ω1 is approximately 0.9 × Ω2, and the relationship between the electrical resistances Ω1 and Ω2 satisfies the relationship Ω1 < Ω2, or more specifically, 0.85 × Ω2 < Ω1 < 0.93 × Ω2.

[0107] (Evaluation Test 1) For the electromagnetic wave-transmitting cover 3 of Example 1 and the electromagnetic wave-transmitting cover 3 of the comparative example, the temperature of the connection region 48 was evaluated by CAE analysis when the heater section 5 was heated so that the temperature of the heating region 47 reached approximately 100°C.

[0108] As a result, in the comparative electromagnetic wave-transmitting cover 3, the temperature of the connection region 48 rose to 118°C at its highest point. As shown in Figure 7, at this time, many dark areas were observed in the connection region 48 of the comparative electromagnetic wave-transmitting cover 3, indicating that the temperature exceeded 110°C. In the comparative electromagnetic wave-transmitting cover 3, the temperature rose particularly high in the portion of the connection region 48 where the general contact portion 51s is located, in other words, the portion of the connection region 48 on the heating region 47 side, as shown by the dashed line in Figure 6.

[0109] In contrast, in the electromagnetic wave-transmitting cover 3 of Example 1, the temperature of the connection region 48 remained at 103°C even at its highest point. As shown in Figure 4, no dark areas were observed in the connection region 48 of the electromagnetic wave-transmitting cover 3 of Example 1 at this time.

[0110] These results confirm that, in the general connection section 51s, by making the distance between the first connection end 511 and the second connection end 512, and the distance between the third connection end 513 and the fourth connection end 514 wider than the distance between the second connection end 512 and the third connection end 513, it is possible to suppress an excessive temperature rise of the heater wire 50 at the connection end 51, and as a result, an excessive temperature rise in the connection region 48 can be suppressed.

[0111] In other words, these results confirm that the electromagnetic wave radar unit 1 and the electromagnetic wave transparent cover 3 of the first embodiment of the present invention can suppress the concentration of heat in the cover body portion 4 of the electromagnetic wave transparent cover 3.

[0112] (Evaluation Test 2) For the electromagnetic wave-transmitting cover 3 of Example 2, the temperature of the connection area 48 was evaluated by CAE analysis when the heater section 5 was heated so that the temperature of the heating area 47 reached approximately 100°C, similar to the evaluation test in Example 1.

[0113] As previously described, in the comparative example electromagnetic wave-transmitting cover 3, the temperature of the connection region 48 rose to 118°C at its highest point. In contrast, the temperature of the connection region 48 in the electromagnetic wave-transmitting cover 3 of Example 2 was lower.

[0114] These results confirm that by making the electrical resistance of the first connection end 511 and the fourth connection end 514 in the general connection section 51s smaller than the electrical resistance of the second connection end 512 and the third connection end 513, excessive temperature rise of the heater wire 50 at the connection end 51 can be suppressed, and as a result, excessive temperature rise in the connection region 48 can be suppressed. In other words, these results confirm that the electromagnetic wave radar unit 1 and the electromagnetic wave transparent cover 3 of the second embodiment of the present invention can suppress deformation of the cover body portion 4 in the electromagnetic wave transparent cover 3.

[0115] Although the present invention has been described above, the present invention is not limited to the embodiments described above, and it is possible to implement the invention by appropriately extracting and combining the elements described in the embodiments, and to make various modifications without departing from the spirit of the present invention. Furthermore, the specification of this invention discloses not only the reference relationships of each claim as initially filed, but also a technical concept that appropriately combines the matters described in each claim. [Explanation of symbols]

[0116] 1: Electromagnetic wave radar unit 2: Electromagnetic radar 3: Electromagnetic wave permeable cover 4: Cover body 48: Connection area 5: Heater section 50: Heater wire 51: Connection end 51s: General Liaison Department 51c: Cross extension section 52: General Heater Section

Claims

1. An electromagnetic wave transparent cover that is placed on the outside of an electromagnetic wave radar, It comprises a cover body made of a plate-shaped, electromagnetically transparent resin material, and a heater part having two heater wires and integrally provided with the cover body, Each of the aforementioned heater wires has connecting ends at both ends and a general heater portion which is the remaining portion and connects the two aforementioned connecting ends. The aforementioned connection end is the end of the electromagnetic wave-transmitting cover and is arranged in parallel with the connection region that extends outward. Each of the aforementioned connecting ends includes a general connecting portion continuous with the general heater portion, and a crossing extension portion continuous with the general connecting portion and extending in a direction intersecting the general connecting portion. An electromagnetic wave-transmitting cover in the general connection section wherein, of the four connection ends of the two heater wires, the distance between the connection end at the outermost end in the arrangement direction and the adjacent connection end is wider than the distance between the two connection ends in the center in the arrangement direction.

2. An electromagnetic wave transparent cover that is placed on the outside of an electromagnetic wave radar, It comprises a cover body made of a plate-shaped, electromagnetically transparent resin material, and a heater part having two heater wires and integrally provided with the cover body, Each of the aforementioned heater wires has connecting ends at both ends and a general heater portion which is the remaining portion and connects the two aforementioned connecting ends. The aforementioned connection end is the end of the electromagnetic wave-transmitting cover and is arranged in parallel with the connection region that extends outward. Each of the aforementioned connecting ends includes a general connecting portion continuous with the general heater portion, and a crossing extension portion continuous with the general connecting portion and extending in a direction intersecting the general connecting portion. An electromagnetic wave-transmitting cover in the general connection section wherein, of the four connection ends of the two heater wires, the electrical resistance of the connection ends at the outermost ends on both sides in the direction of arrangement is smaller than the electrical resistance of the two connection ends in the center in the direction of arrangement.

3. The electromagnetic wave-transmitting cover according to claim 1 or claim 2, wherein the cover body is made of resin with a glass transition temperature of 120°C or more and 140°C or less.

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