Electromagnetic wave transmission cover

Abstract

To cope with both of uniformity in the heat generation distribution and improvement of appearance.SOLUTION: A heater film 25 of a mm-wave transmission cover 20 as an electromagnetic wave transmission cover includes a conductive part 32 formed of a conductive material. A first electrode part 40 and a second electrode part 45 of the conductive part 32 are positioned in places that are outside a mm-wave transmission area Z1 and oppose while sandwiching the transmission area Z1, and are extended in a direction that crosses the opposing directions each. Each of multiple heater wire parts 51, 55 of the conductive part 32 has first ends 53, 58 and second ends 54, 62. The first ends 53, 58 for the respective heater wire parts 51, 55 are connected to the first electrode part 40, and the second ends 54, 62 are connected to the second electrode part 45. The first electrode part 40 and the second electrode part 45 have a line width wider than line widths of the heater wire parts 51, 55.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electromagnetic wave transmission and reception device that transmits and receives electromagnetic waves such as millimeter waves, and an electromagnetic wave transmission cover that covers the device from the front in the electromagnetic wave transmission direction.

Background Art

[0002] In a vehicle equipped with a device that transmits and receives electromagnetic waves such as millimeter waves, electromagnetic waves are transmitted from the device toward the outside of the vehicle. Electromagnetic waves reflected by hitting an object outside the vehicle, including a preceding vehicle, a pedestrian, etc., are received by the above device. Then, the above device recognizes the above object based on the transmitted and received electromagnetic waves, and detects the distance, relative speed, etc. between the vehicle and the object.

[0003] In the above vehicle, an electromagnetic wave transmission cover that transmits electromagnetic waves is disposed in front of the above device in the electromagnetic wave transmission direction. The electromagnetic wave transmission cover has a layer structure in which a plurality of layers are laminated in the above transmission direction, and covers the above device from the front in the above transmission direction.

[0004] Here, when ice and snow adhere to the electromagnetic wave transmission cover, the electromagnetic waves are attenuated, and there is a problem that the detection performance of the above device deteriorates. Therefore, an electromagnetic wave transmission cover with a heater film added has been proposed (for example, see Patent Document 1).

[0005] The heater film includes a conductive portion formed of a conductive material. The conductive portion includes an electrode portion and a heater wire portion connected to the electrode portion. The heater wire portion includes a plurality of straight portions arranged in a separated state from each other, and an arc-shaped connecting portion that connects the ends of adjacent straight portions.

[0006] According to the above electromagnetic wave transmission cover, when power is supplied to the conductive portion, the heater wire portion generates heat. Therefore, even if ice and snow adhere to the electromagnetic wave transmission cover, the heat generated by the heater wire portion can melt the ice and snow, and suppress the attenuation of electromagnetic waves caused by the adhesion of ice and snow.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent No. 6719506 [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] However, in the electromagnetic wave transmission cover described in the above Patent Document 1, if the electrode portion has a line width similar to that of the heater wire portion, the electrode portion may generate heat in the same manner as the heater wire portion due to energization. In this case, it is difficult to heat the region of the heater film where heat generation is desired with a uniform heat generation distribution. Further, in the electromagnetic wave transmission cover described in the above Patent Document 1, since the line width of the heater wire portion is as large as 50 μm to 70 μm, the heater wire portion is likely to be visually recognized, and there is also a problem that the appearance deteriorates. [Means for Solving the Problems]

[0009] The electromagnetic wave transmission cover for solving the above problems is applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, is disposed in front of the device in the transmission direction of the electromagnetic waves, and has a layer structure in which a plurality of layers are laminated in the transmission direction. The electromagnetic wave transmission cover is such that one of the plurality of layers is constituted by a heater film. The heater film includes a conductive portion formed of a conductive material. The conductive portion includes a plurality of heater wire portions, a first electrode portion, and a second electrode portion. The first electrode portion and the second electrode portion are located outside the transmission region of the electromagnetic waves and face each other with the transmission region therebetween. When the direction in which the first electrode portion and the second electrode portion face each other is defined as the facing direction and the direction intersecting the facing direction is defined as the intersecting direction, the first electrode portion and the second electrode portion each extend in the intersecting direction. Each of the plurality of heater wire portions has a first end portion and a second end portion. The first end portion of each heater wire portion is connected to the first electrode portion, and the second end portion of each heater wire portion is connected to the second electrode portion. Further, the first electrode portion and the second electrode portion have a line width larger than the line width of the heater wire portion.

[0010] According to the above configuration, in the conductive portion of the electromagnetic wave transmission cover, when current flows in the order of the first electrode portion, the plurality of heater wire portions, and the second electrode portion, or conversely, when current flows in the order of the second electrode portion, the plurality of heater wire portions, and the first electrode portion, each heater wire portion generates heat.

[0011] Here, the first electrode portion and the second electrode portion are located outside the electromagnetic wave transmission region and face each other across the transmission region, and each extends in a crossing direction intersecting the facing direction. Each of the plurality of heater wire portions is formed between the first electrode portion and the second electrode portion, is connected to the first electrode portion at the first end portion, and is connected to the second electrode portion at the second end portion. In this way, the plurality of heater wire portions are formed in a wide area. Therefore, it is possible to generate heat in a wide area of the heater film.

[0012] In addition, since the plurality of heater wire portions are connected in parallel to the first electrode portion and the second electrode portion, the same voltage is applied to each heater wire portion. Therefore, it is possible to make each heater wire portion generate heat uniformly.

[0013] Furthermore, since the line widths of the first electrode portion and the second electrode portion are larger than the line width of the heater wire portion, the resistances of the first electrode portion and the second electrode portion are smaller than the resistance of the heater wire portion. The first electrode portion and the second electrode portion do not generate as much heat as the heater wire portion even when generating heat. Therefore, it is possible to make the heater film generate heat with a uniform heat distribution by the heater wire portion.

[0014] Also, it is possible to make the line width of each heater wire portion smaller than the case where the heater wire portion is connected in series to the first electrode portion and the second electrode portion. Also, by increasing the number of heater wire portions, it is possible to make the line width of each heater wire portion smaller.

[0015] As the line width of the heater wire portion becomes smaller, the heater wire portion becomes less visible, and the appearance of the heater film and thus the electromagnetic wave transmission cover is improved. In the electromagnetic wave transmission cover, it is preferable that each of the first electrode portion and the second electrode portion is formed with a slit extending in the crossing direction.

[0016] According to the above configuration, due to the formation of the slit, the first electrode portion and the second electrode portion are less conspicuous compared to those without the slit formed, and the appearance is further improved. Also, in the heater film, the rigidity difference becomes smaller between the portion where the first electrode portion and the second electrode portion are formed and the portion where they are not formed, particularly between the first electrode portion and the second electrode portion and the surrounding portions. Therefore, it is possible to make it easier to bend the portion where the first electrode portion and the second electrode portion are formed in the heater film.

[0017] In the electromagnetic wave transmission cover, each of a plurality of the heater wire portions located at least in the middle portion in the crossing direction is constituted by a straight portion that extends linearly in the facing direction as a whole, and it is preferable that the straight portions for each of the plurality of the heater wire portions located at least in the middle portion in the crossing direction extend in the facing direction while being spaced apart from each other in parallel in the crossing direction.

[0018] According to the above configuration, in a plurality of heater wire portions located at least in the middle portion in the crossing direction, the intervals between adjacent straight portions are uniform in the facing direction. Therefore, it is possible to cause heat generation with a uniform heat generation distribution between adjacent straight portions in the facing direction compared to the case where the above intervals are different in the facing direction.

[0019] Also, compared to the case where the intervals between adjacent straight portions are different in the facing direction, the same straight portions are less likely to be visually recognized. In the electromagnetic wave transmission cover, in a plurality of the heater wire portions located at least in the middle portion in the crossing direction, it is preferable that the straight portions are formed at regular intervals in the crossing direction.

[0020] According to the above configuration, in a plurality of heater wire portions located at least in the intermediate part in the crossing direction, the intervals between adjacent straight portions are uniform in the crossing direction. Therefore, compared with the case where the intervals between adjacent straight portions are different in the crossing direction, it becomes easier to cause the heater film to generate heat with a uniform heat generation distribution in the crossing direction.

[0021] Also, a plurality of straight portions are evenly arranged in the crossing direction, and compared with the case where the intervals between adjacent straight portions are different in the crossing direction, the heater wire portions are less likely to be visually recognized. In the electromagnetic wave transmission cover, one of the first electrode portion and the second electrode portion is curved so as to bulge toward the side away from the other, and the other is curved so as to bulge toward the side away from the one. Among the plurality of heater wire portions, it is preferable that the heater wire portions located on both side portions in the crossing direction are formed longer than when the whole extends linearly in the facing direction.

[0022] When the first electrode portion and the second electrode portion are curved as described above, the interval between both electrode portions is the widest at the central portion in the crossing direction. The interval becomes narrower as it moves away from the central portion in the crossing direction.

[0023] Accordingly, in the central portion in the crossing direction, the straight portion of the heater wire portion becomes longer than other portions. The length of the straight portion becomes shorter as it moves away from the central portion in the crossing direction. As the length becomes shorter, the calorific value of the heater wire portion decreases. The heat generation has a distribution in which the calorific value is large at the central portion in the crossing direction and decreases as it moves away from the central portion in the crossing direction.

[0024] In this regard, according to the above configuration, among the plurality of heater wire portions, the heater wire portions located on both side portions in the crossing direction are formed longer than when the whole extends linearly in the facing direction. By being lengthened as described above, the calorific value of the heater wire portions at both side portions increases. Accordingly, the variation in the heat generation distribution in the crossing direction becomes smaller.

[0025] In the electromagnetic wave transmitting cover, the heater wire portions located on both sides in the crossing direction are composed of a straight portion linearly extending outward in the crossing direction and in the facing direction from the first electrode portion and the second electrode portion, a first extension portion extending from one end of the straight portion toward the first electrode portion and having the first end portion, and a second extension portion extending from the other end of the straight portion toward the second electrode portion and having the second end portion. It is preferable that the first extension portion is connected to the first electrode portion at the first end portion, and the second extension portion is connected to the second electrode portion at the second end portion.

[0026] According to the above configuration, the heater wire portions located on both sides in the crossing direction are composed of the straight portion, the first extension portion, and the second extension portion. The heater wire portions on both sides are longer by the lengths of the first extension portion and the second extension portion than in the case where they are composed of only the straight portion.

[0027] In addition, with the formation of the first extension portion, the length of the first electrode portion in the crossing direction becomes shorter. Accordingly, the first electrode portion becomes less conspicuous, and the appearance is further improved. Also, with the formation of the second extension portion, the length of the second electrode portion in the crossing direction becomes shorter. Accordingly, the second electrode portion becomes less conspicuous, and the appearance is further improved.

[0028] In the electromagnetic wave transmission cover, the conductive portion further includes a plus terminal portion and a minus terminal portion to which devices for power supply are connected. The first electrode portion includes a first plus electrode portion connected to the plus terminal portion and a first minus electrode portion formed in a state of being separated from the first plus electrode portion and connected to the minus terminal portion. The first plus electrode portion and the first minus electrode portion are adjacent to each other at least in a state of being separated in the intersecting direction. The second electrode portion is an intermediate electrode portion between the first plus electrode portion and the first minus electrode portion, faces the first plus electrode portion and the first minus electrode portion, the first end portion of a part of the heater wire portion is connected to the first plus electrode portion, the second end portion of the part of the heater wire portion is connected to the second electrode portion, the first end portion of the remaining part of the heater wire portion is connected to the first minus electrode portion, and the second end portion of the remaining part of the heater wire portion is preferably connected to the second electrode portion.

[0029] According to the above configuration, when power is supplied from the device to the conductive portion, current flows in the order of the plus terminal portion, the first plus electrode portion, the ones among the plurality of heater wire portions connected to the first plus electrode portion, and the second electrode portion. Also, the current flows in the order of the second electrode portion, the ones among the plurality of heater wire portions connected to the first minus electrode portion, the first minus electrode portion, and the minus terminal portion. The direction of the current flowing from the first plus electrode portion toward the second electrode portion and the direction of the current flowing from the second electrode portion toward the first minus electrode portion are opposite directions.

[0030] Therefore, it becomes possible to make the current flow evenly throughout the plurality of heater wire portions. Along with this, it becomes possible to make the heater film generate heat with a more uniform heat generation distribution.

Effect of the Invention

[0031] According to the electromagnetic wave transmission cover, it is possible to achieve both the uniformization of the heat generation distribution and the improvement of the appearance.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

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Figure 11

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Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, an embodiment in which the electromagnetic wave transmission cover is embodied as a millimeter wave transmission cover for a vehicle will be described with reference to the drawings. In the following description, the forward direction of the vehicle is defined as the front, and the reverse direction is defined as the rear. Also, the up-down direction means the up-down direction of the vehicle, and the left-right direction means the vehicle width direction, which coincides with the left-right direction when the vehicle is moving forward. Further, in FIG. 2, in order to show each part of the millimeter wave transmission cover in a recognizable size, the scale is appropriately changed to show each part.

[0034] As shown in FIGS. 1 and 2, at the central portion in the left-right direction at the front part of the vehicle 10, behind the front grille 11, a millimeter wave radar device 13 for forward monitoring is mounted as a device for transmitting and receiving electromagnetic waves. In FIG. 2, only a part of the millimeter wave radar device 13 is shown. The millimeter wave radar device 13 has a function of transmitting millimeter waves in the electromagnetic waves toward the front outside the vehicle and receiving the millimeter waves reflected by hitting an object outside the vehicle. The millimeter wave refers to an electric wave having a wavelength of 1 mm to 10 mm and a frequency of 30 GHz to 300 GHz.

[0035] In this embodiment, as described above, since the millimeter wave radar device 13 transmits millimeter waves toward the front of the vehicle 10, the transmission direction of the millimeter waves by the millimeter wave radar device 13 is the direction from the rear to the front of the vehicle 10. The front in the transmission direction of the millimeter waves generally coincides with the front of the vehicle 10, and the rear in the same transmission direction generally coincides with the rear of the vehicle 10. Therefore, in the following description, the front in the transmission direction of the millimeter waves is simply referred to as "front", "forward", etc., and the rear in the same transmission direction is simply referred to as "rear", "backward", etc.

[0036] The thickness of the front grille 11 is not constant, similar to a general front grille. Also, in the front grille 11, a metal plating layer may be formed on the surface of the resin base material. The front grille 11 may interfere with the transmitted or reflected millimeter waves. For this reason, in the front grille 11, a window portion 12 is opened in front of the millimeter wave radar device 13 in the transmission direction of the millimeter waves, and a millimeter wave transmission cover 20 is disposed here. The millimeter wave transmission cover 20 covers the millimeter wave radar device 13 from the front.

[0037] The main part of the millimeter-wave transmission cover 20 is constituted by a cover main body 21. In FIG. 2, only a part of the cover main body 21 is shown. The cover main body 21 has an elliptical shape with dimensions in the left-right direction larger than those in the up-down direction when viewed from the front. The cover main body 21 is arranged in an upright state such that its front face faces forward and its rear face faces backward. The front face of the cover main body 21 constitutes a design surface 22.

[0038] A part of the region that is inward from the edge of the outer periphery of the cover main body 21 is a millimeter-wave transmission region Z1 for the millimeter waves transmitted from the millimeter-wave radar device 13 (see FIG. 3). The cover main body 21 has a layer structure in which a plurality of layers are laminated in the front-rear direction. The plurality of layers include a cover base material 23, a heater film 25, and a protection part 70. Next, each layer will be described.

[0039] <Cover base material 23> The cover base material 23 is formed by resin molding using a resin material having millimeter-wave transmissibility as electromagnetic wave transmissibility. The resin material used for forming the cover base material 23 may be transparent or opaque. In the present embodiment, the cover base material 23 is formed of a PC (polycarbonate) resin, but it may be formed of other resin materials, for example, an ABS (acrylonitrile-butadiene-styrene copolymer) resin.

[0040] <Heater film 25> The heater film 25 is for adding a snow melting function to the millimeter-wave transmission cover 20 and is arranged in front of the cover base material 23. The heater film 25 is shaped to correspond to the shape of the front face of the cover base material 23. The heater film 25 includes a film base material 26, an adhesive layer 31, a conductive part 32, and a resist layer 65.

[0041] 〈Film base material 26> The film base material 26 forms the framework portion of the heater film 25. The film base material 26 has millimeter-wave transmissivity and is formed of a transparent resin material. In the present embodiment, the film base material 26 is formed of a PET (polyethylene terephthalate) resin.

[0042] FIG. 3 shows the heater film 25 before the resist layer 65 is formed. As shown in FIGS. 2 and 3, the film base material 26 includes a main body portion 27 and a connection portion 29. The main body portion 27 has a shape that, when viewed from the front, corresponds to the shape of the cover main body portion 21, that is, an elliptical shape with larger dimensions in the left-right direction than in the up-down direction. The upper portion 28U and the lower portion 28L at the edge 28 of the main body portion 27 are outside the millimeter-wave transmission region Z1 and are located at positions facing each other across the transmission region Z1 from both sides in the up-down direction.

[0043] Here, among the radial directions of the elliptical main body portion 27, the direction approaching the center O (the intersection of the major axis and the minor axis) is referred to as the "inward direction", and the direction away from the center O is referred to as the "outward direction". Also, the direction along the edge 28 of the main body portion 27 is referred to as the "circumferential direction".

[0044] As shown in FIG. 10, the connection portion 29 is a location where a device 82 for power supply is connected, and extends outward in the radial direction from a part of the edge 28 of the main body portion 27. Furthermore, as shown in FIG. 3, the location below the center O of the main body portion 27 in the lower portion 28L is referred to as the "central portion 28C of the lower portion 28L".

[0045] In the present embodiment, the connection portion 29 extends obliquely downward to the left in the radial direction with a point shifted to the left with respect to the central portion 28C as a base point. <Adhesive layer 31> As shown in FIG. 2, the adhesive layer 31 has a function of adhering the conductive portion 32 to the film base material 26, and is formed on the entire rear surface of each of the main body portion 27 and the connection portion 29 in the film base material 26. As the adhesive layer 31, for example, a transparent film-like optical adhesive sheet called OCA (OPTICAL CLEAR ADHESIVE) can be used.

[0046] Note that the "transparent" in the cover base material 23, the film base material 26, and the adhesive layer 31 includes not only colorless transparency but also colored transparency (colored transparency). This also applies to the resin sheet 71 and the adhesive layer 72 of the protection portion 70 described later.

[0047] <Conductive portion 32> The conductive portion 32 is formed of a foil made of a conductive material, for example, a copper foil, a silver foil, or the like. The conductive portion 32 is adhered to the film base material 26 via the adhesive layer 31. As shown in FIGS. 3 and 10, the conductive portion 32 includes a pair of terminal portions, a first electrode portion 40 and a second electrode portion 45, and a plurality of heater wire portions 51 and 55.

[0048] [A pair of terminal portions] The pair of terminal portions is composed of a plus terminal portion 33 and a minus terminal portion 34 formed on the rear surface of the connection portion 29 via the adhesive layer 31, respectively.

[0049] As shown in FIGS. 13 and 14, the plus terminal portion 33 and the minus terminal portion 34 include a plurality of first conductor portions 35 arranged in a state of being parallel and spaced apart from each other, and a plurality of second conductor portions 36 intersecting the respective first conductor portions 35 and arranged in a state of being parallel and spaced apart from each other. In the present embodiment, each first conductor portion 35 and each second conductor portion 36 are orthogonal to each other. A square mesh is formed by two adjacent first conductor portions 35 and two adjacent second conductor portions 36. The plus terminal portion 33 and the minus terminal portion 34 form a mesh shape in which the meshes are arranged vertically and horizontally. The plus terminal portion 33 and the minus terminal portion 34 are spaced apart from each other in the circumferential direction of the main body portion 27.

[0050] When the connection part 29, the plus terminal part 33, and the minus terminal part 34 are incorporated in the millimeter-wave transmission cover 20, although not shown in the drawings, they are bent backward along the lower surface of the edge of the cover base material 23.

[0051] As shown in FIG. 10, the extended end part 33a of the plus terminal part 33 and the extended end part 34a of the minus terminal part 34 are not covered by the resist layer 65 described later. Connector pins (not shown) are fixed to each of these extended end parts 33a, 34a by fixing means such as soldering, adhesion, caulking, etc. Both the extended end parts 33a, 34a and both the connector pins are arranged in the socket part 81 arranged behind the cover base material 23 together with a part of the connection part 29 in the film base material 26.

[0052] [First Electrode Part 40 and Second Electrode Part 45] As shown in FIGS. 3 and 10, the first electrode part 40 and the second electrode part 45 are respectively formed via the adhesive layer 31 with respect to the edge part 28 on the rear surface of the main body part 27. The first electrode part 40 and the second electrode part 45 are located outside the millimeter-wave transmission region Z1 and face each other across the transmission region Z1 from both sides in the vertical direction. The first electrode part 40 is composed of a first plus electrode part 41 and a first minus electrode part 42.

[0053] As shown in FIGS. 5, 7, and 12, the first plus electrode part 41 extends substantially in the left-right direction along the lower part 28L. The first plus electrode part 41 is gently curved so as to bulge downward. The first plus electrode part 41 includes a narrow-width part 41a and a wide-width part 41b having a larger line width than the narrow-width part 41a. The narrow-width part 41a extends substantially to the left from the vicinity of the left side of the central part 28C. The wide-width part 41b extends substantially to the right from the vicinity of the left side of the central part 28C.

[0054] As shown in FIGS. 3 and 10, the first plus electrode part 41 is connected to the plus terminal part 33 at the left end of the narrow-width part 41a. The right end of the wide-width part 41b is located near the right end of the main body part 27.

[0055] As shown in FIGS. 7, 9, and 10, the first negative electrode portion 42 extends substantially in the left - right direction along the lower portion 28L. The first negative electrode portion 42 is gently curved so as to bulge downward. The first negative electrode portion 42 is connected to the negative terminal portion 34 at its intermediate portion in the direction along the lower portion 28L. As shown in FIGS. 3 and 9, the left end portion of the wide portion 42b is located near the left end portion of the main body portion 27.

[0056] As shown in FIGS. 7 and 10, in the first negative electrode portion 42, the portion to the right of the connection portion with the negative terminal portion 34 is constituted by a narrow - width portion 42a having a narrow line width. The right end portion of the narrow - width portion 42a is located at a position separated to the left from the central portion 28C and is slightly separated to the left from the wide portion 41b. In the first negative electrode portion 42, the portion to the left of the connection portion with the negative terminal portion 34 is constituted by a wide - width portion 42b having a larger line width than the narrow - width portion 42a.

[0057] As shown in FIGS. 10 and 12, the narrow - width portion 41a of the first positive electrode portion 41 and the narrow - width portion 42a of the first negative electrode portion 42 are arranged side by side in a state of being separated in the radial direction. On the other hand, as shown in FIGS. 3 and 6, the second electrode portion 45 has a function as a relay electrode portion between the first positive electrode portion 41 and the first negative electrode portion 42. The second electrode portion 45 is formed via an adhesive layer 31 on the upper portion 28U, which is a portion of the edge portion 28 that faces the lower portion 28L with the transmission region Z1 interposed therebetween. The second electrode portion 45 extends substantially in the left - right direction along the upper portion 28U. The second electrode portion 45 is gently curved so as to bulge upward. The line width of the second electrode portion 45 is uniform in the circumferential direction, which is the direction along the upper portion 28U. The right end portion of the second electrode portion 45 is located above the right end portion of the first positive electrode portion 41. The left end portion of the second electrode portion 45 is located above the left end portion of the first negative electrode portion 42.

[0058] As described above, the first electrode portion 40 and the second electrode portion 45 face each other in the vertical direction with the transmission region Z1 therebetween. Here, the direction along the rear surface of the main body portion 27 and in which the first electrode portion 40 and the second electrode portion 45 face each other is referred to as the "opposing direction". Also, the direction intersecting the opposing direction is referred to as the "intersecting direction". The intersecting direction includes not only the direction orthogonal to the opposing direction but also the direction intersecting obliquely. In the present embodiment, the substantially left-right direction, which is substantially orthogonal to the opposing direction, corresponds to the intersecting direction.

[0059] As shown in FIGS. 12 and 13, a plurality of slits 43 extending in the intersecting direction along the lower portion 28L are formed in each of the first plus electrode portion 41 and the first minus electrode portion 42. Each slit 43 extends in the substantially left-right direction while gently curving so as to bulge downward. The slits 43 are formed at a plurality of locations in each of the first plus electrode portion 41 and the first minus electrode portion 42 in the direction along the lower portion 28L. The slits 43 adjacent to each other in the direction along the lower portion 28L are separated from each other in the same direction with a connecting portion 44 provided between the two slits 43. Also, the slits 43 are formed at a plurality of locations in each of the first plus electrode portion 41 and the first minus electrode portion 42 in the radial direction. The plurality of slits 43 in the radial direction are separated from each other in the same direction.

[0060] Here, the value obtained by subtracting the width of all the slits 43 from the actual line width of the wide portion 41b when it is assumed that no slit 43 is formed is defined as the substantial line width of the first plus electrode portion 41. Similarly, the value obtained by subtracting the width of all the slits 43 from the actual line width of the wide portion 42b when it is assumed that no slit 43 is formed is defined as the substantial line width of the first minus electrode portion 42. The actual line width and the substantial line width of the first plus electrode portion 41 are larger than the line widths of the heater wire portions 51 and 55 described later. Similarly, the actual line width and the substantial line width of the first minus electrode portion 42 are also larger than the line widths of the heater wire portions 51 and 55.

[0061] As shown in FIG. 11, a plurality of slits 46 extending in the intersecting direction along the upper portion 28U are formed in the second electrode portion 45. Each slit 46 extends substantially in the left - right direction while gently curving so as to bulge upward. The slits 46 are formed at a plurality of locations of the second electrode portion 45 in the direction along the upper portion 28U. The slits 46 adjacent to each other in the direction along the upper portion 28U are separated from each other in the same direction with a connecting portion 47 provided between the two slits 46. Also, the slits 46 are formed at a plurality of locations of the second electrode portion 45 in the radial direction. The plurality of slits 46 in the radial direction are separated from each other in the same direction.

[0062] Here, a value obtained by subtracting the width of all the slits 46 from the actual line width of the second electrode portion 45 when it is assumed that no slit 46 is formed is defined as the substantial line width of the second electrode portion 45. The actual line width and the substantial line width of the second electrode portion 45 are larger than the line widths of the heater wire portions 51, 55.

[0063] [a plurality of heater wire portions 51, 55] As shown in FIG. 3, the plurality of heater wire portions 51, 55 adopt different forms in the intermediate portion and the both side portions in the intersecting direction.

[0064] As shown in FIGS. 3 and 7, the plurality of heater wire portions 51 located in the intermediate portion are entirely constituted by straight portions 52 extending linearly in the facing direction. Each straight portion 52 is formed in a state of being separated from each other in the intersecting direction. The straight portion 52 of the heater wire portion 51 located at the central portion in the intersecting direction is located on or close to the center O.

[0065] As shown in FIGS. 6 and 7, each heater wire portion 51 has a first end portion 53 at the lower end and a second end portion 54 at the upper end. The first end portion 53 of each heater wire portion 51 is connected to the first electrode portion 40. More specifically, some of the heater wire portions 51, in this case, the heater wire portion 51 located at the central portion in the above-mentioned crossing direction and the heater wire portion 51 located on the right side thereof are connected to the first plus electrode portion 41 at the first end portion 53. The remaining heater wire portions 51, in this case, the heater wire portions 51 located on the left side of the central portion in the above-mentioned crossing direction are connected to the first minus electrode portion 42 at the first end portion 53.

[0066] On the other hand, the second end portion 54 of each heater wire portion 51 is connected to the second electrode portion 45. As shown in FIG. 3, the distance between the first electrode portion 40 and the second electrode portion 45 that are curved so as to bulge in opposite directions is the widest at the central portion in the above-mentioned crossing direction. The above-mentioned distance becomes narrower as it moves away from the central portion in the above-mentioned crossing direction. At the central portion in the above-mentioned crossing direction, the length of the heater wire portion 51 is longer than other portions. The length of the heater wire portion 51 becomes shorter as it moves away from the central portion in the above-mentioned crossing direction.

[0067] The heater wire portions 55 located on both sides in the above-mentioned crossing direction, in this embodiment, two heater wire portions 55 are formed longer for each side than when they extend linearly in the above-mentioned facing direction as a whole. Each heater wire portion 55 is composed of a straight portion 56, a first extension portion 57, and a second extension portion 61. The straight portion 56 of each heater wire portion 55 extends linearly in the above-mentioned facing direction outside the first electrode portion 40 and the second electrode portion 45 in the above-mentioned crossing direction. Both ends of each straight portion 56 are located at the lower portion 28L and the upper portion 28U of the edge portion 28.

[0068] The straight portions 56 of the two heater wire portions 55 for each side are shorter than any of the straight portions 52 of the plurality of heater wire portions 51. Also, the length of the two straight portions 56 for each side is shorter for those farther from the central portion in the above-mentioned crossing direction.

[0069] For each heater wire portion 55, the first extension portion 57 extends from the lower end portion of the straight portion 56 along the lower portion 28L toward the first electrode portion 40. Each first extension portion 57 is gently curved so as to bulge downward corresponding to the lower portion 28L and has a first end portion 58. The first end portion 58 of each first extension portion 57 is connected to the first electrode portion 40 from the side. The adjacent first extension portions 57 on the same side portion are spaced apart from each other in the radial direction. Also, among the two first extension portions 57, the one connected to the straight portion 56 farther from the central portion in the crossing direction is longer.

[0070] For each heater wire portion 55, the second extension portion 61 extends from the upper end portion of the straight portion 56 along the upper portion 28U toward the second electrode portion 45. Each second extension portion 61 is gently curved so as to bulge upward corresponding to the upper portion 28U and has a second end portion 62. The second end portion 62 of each second extension portion 61 is connected to the second electrode portion 45 from the side. The adjacent second extension portions 61 on the same side portion are spaced apart from each other in the radial direction. Also, among the two second extension portions 61, the one connected to the straight portion 56 farther from the central portion in the crossing direction is longer.

[0071] By adding the first extension portion 57 and the second extension portion 61 as described above, the total length of the two heater wire portions 55 for each side portion is made closer to the total length of the heater wire portion 51 located at the central portion in the crossing direction.

[0072] In the present embodiment, the straight portions 52, 56 of the plurality of heater wire portions 51, 55 are formed at regular intervals in the crossing direction. The intervals between the adjacent straight portions 52, 56 are uniform in the crossing direction. The intervals between the adjacent straight portions 52, 56 are preferably 2 mm or more in order to ensure the transmission of millimeter waves. However, if the intervals become too large, the heat generated by the straight portions 52, 56 is less likely to be transmitted to the central portion between the adjacent straight portions 52, 56. Therefore, the intervals are comprehensively judged from viewpoints such as ensuring the required transmission of millimeter waves, equalizing the heat generation distribution, resistance value, and design, and are set. In the present embodiment, the intervals are set to about 4 mm.

[0073] The line widths of the respective heater wire portions 51 and 55 are set to about 10 μm. In addition, in the main body portion 27, in the both end portions in the above intersection direction, in other words, in the region outside the heater wire portion 55, no heater wire portion is formed.

[0074] <Resist layer 65> As shown in FIGS. 2 and 3, the resist layer 65 is made of an insulating material, and insulates the same location by covering different locations of the conductive portion 32, namely, the extending end portion 33a of the plus terminal portion 33 and the extending end portion 34a of the minus terminal portion 34. Both extending end portions 33a and 34a are exposed from the resist layer 65. The above-described connector pins are fixed in a conductive state to the exposed portions.

[0075] 〈Regarding the production of the heater film 25〉 The heater film 25 having the above configuration is produced as follows. By attaching the above OCA to the rear surface of the film base material 26 shown in FIG. 2, the adhesive layer 31 is formed.

[0076] The film base material 26 having the adhesive layer 31 formed thereon and a foil made of a conductive material, here a copper foil, are pushed toward each other by a roller or the like. The foil is attached to the film base material 26 by the adhesive layer 31.

[0077] Next, patterning is performed on the above foil. The patterning is a processing method for forming the above conductive portion 32 by removing unnecessary portions of the foil on the adhesive layer 31 by performing a photolithography and optical mask process, and it is also possible to process the heater wire portions 51 and 55 having a small line width.

[0078] The resist layer 65 is formed by applying a solder resist or the like around the locations of the conductive portion 32 that are different from the extending end portions 33a and 34a. In this way, the heater film 25 including the film base material 26, the adhesive layer 31, the conductive portion 32, and the resist layer 65 is created.

[0079] Note that the bonding of the heater film 25 to the cover base material 23 is performed, for example, as follows. The heater film 25 is shaped to correspond to the shape of the front surface of the cover base material 23. As shown in FIG. 2, a binder layer 67 is bonded to the rear surface of the heater film 25. The binder layer 67 is formed of a resin material capable of bonding to the cover base material 23, for example, a PMMA (polymethyl methacrylate) resin, the above-mentioned ABS resin, or the like.

[0080] The heater film 25 with the binder layer 67 attached is placed in the mold as an insert. The resin material in a molten state is filled behind the binder layer 67 in the mold, and the cover base material 23 is insert-molded. During this molding, heat is transferred from the molten resin material to the binder layer 67 and pressure is applied, so that the binder layer 67 exhibits an adhesive force. The adhesion between the cover base material 23 and the heater film 25 is enhanced by the binder layer 67.

[0081] <Protective portion 70> The protective portion 70 includes a resin sheet 71 and an adhesive layer 72, is in a sheet shape, and is disposed in front of the film base material 26. The protective portion 70 serves to protect the heater film 25, particularly the conductive portion 32, from an impact such as a flying stone when an impact is applied to the cover main body portion 21 from the front.

[0082] The resin sheet 71 is formed of a transparent resin material having millimeter-wave transmissivity. In the present embodiment, the resin sheet 71 is formed of a PC resin. The resin sheet 71 is shaped to correspond to the shape of the front surface of the film base material 26.

[0083] The adhesive layer 72 is formed of OCA, similar to the above-mentioned adhesive layer 31. The adhesive layer 72 adhesively bonds the resin sheet 71 to the front surface of the film base material 26 in a close contact state. The front surface of the resin sheet 71 constitutes the design surface 22 of the millimeter-wave cover 20.

[0084] The millimeter-wave transmission cover 20 includes an attachment portion (not shown) in addition to the cover main body portion 21, and is attached to the front grille 11 or the vehicle body at this attachment portion. As shown in FIG. 10, further, a connector 83 of the device 82 for power supply is coupled to the socket portion 81. By this coupling, the plus terminal portion 33 and the minus terminal portion 34 are electrically connected to the device 82 via connector pins.

[0085] Next, the operation of the present embodiment configured as described above will be described. Also, the effects resulting from the operation will be described together. When millimeter waves are transmitted from the millimeter-wave radar device 13 shown in FIG. 2, the millimeter waves pass through each part in the transmission region Z1 of the cover main body portion 21. The transmitted millimeter waves hit an object in front of the vehicle including a preceding vehicle, a pedestrian, etc., are reflected, and then pass through the cover main body portion 21 again and are received by the millimeter-wave radar device 13. The millimeter-wave radar device 13 recognizes the object based on the transmitted and received millimeter waves, and detects the distance, relative speed, etc. between the vehicle 10 and the same object.

[0086] <Improvement in millimeter-wave transmissibility> (1-1) As shown in FIG. 3, in the plurality of heater wire portions 51, 55, the interval between adjacent straight portions 52, 56 is set to about 4 mm. Therefore, millimeter waves easily pass through between the adjacent straight portions 52, 56. The straight portions 52, 56 are less likely to obstruct the transmission of millimeter waves.

[0087] (1-2) If the heater wire portions 51, 55 are thick, millimeter waves are reflected by the heater wire portions 51, 55 and attenuated. In this regard, in the present embodiment, the line width of each heater wire portion 51, 55 is set to about 10 μm. Therefore, compared with Patent Document 1 in which the line width of the heater wire portion is 50 μm to 70 μm, reflection of millimeter waves at the heater wire portions 51, 55 is suppressed, and millimeter waves easily pass through. Also in this regard, each heater wire portion 51, 55 is less likely to obstruct the transmission of millimeter waves.

[0088] (1-3) The first plus electrode portion 41, the first minus electrode portion 42, and the second electrode portion 45 are located outside the millimeter-wave transmission region Z1. Therefore, the line width of each of the first plus electrode portion 41, the first minus electrode portion 42, and the second electrode portion 45 is larger than the line width of the heater wire portions 51 and 55, but it is less likely to interfere with the transmission of millimeter waves.

[0089] According to the above (1-1) to (1-3), in this embodiment, it is possible to suppress a decrease in the millimeter-wave transmissivity due to the addition of the heater film 25. Here, when ice and snow adhere to the design surface 22 of the cover main body portion 21 shown in FIG. 1, the millimeter waves are attenuated, and the detection performance of the millimeter-wave radar device 13 deteriorates. In this regard, in this embodiment, power is supplied from the device 82 shown in FIG. 10 to the conductive portion 32.

[0090] In the conductive portion 32 shown in FIG. 3, the current flows in the order of the plus terminal portion 33, the first plus electrode portion 41, the one among the plurality of heater wire portions 51 and 55 that is connected to the first plus electrode portion 41 and is located on the right side portion of the main body portion 27, and the second electrode portion 45. Also, the current flows in the order of the second electrode portion 45, the one among the plurality of heater wire portions 51 and 55 that is connected to the first minus electrode portion 42 and is located on the left side portion of the main body portion 27, the first minus electrode portion 42, and the minus terminal portion 34.

[0091] Each of the heater wire portions 51 and 55 generates heat when current flows through it. A part of the heat generated by each of the heater wire portions 51 and 55 is transmitted to the design surface 22 through the adhesive layer 31, the film base material 26, and the protection portion 70 in FIG. 2. Due to this heat, the ice and snow adhering to the design surface 22 are melted. It is possible to suppress the attenuation of millimeter waves by ice and snow and suppress the deterioration of the detection performance of the millimeter-wave radar device 13 caused by the adhesion of ice and snow.

[0092] <Improvement in the uniformity of the heat generation distribution> (2-1) As shown in FIG. 3, the first electrode portion 40 and the second electrode portion 45 are each formed at a position behind the edge portion 28 of the main body portion 27 and facing each other in the vertical direction. The right end portions of the first electrode portion 40 and the second electrode portion 45 are located near the right end portion of the main body portion 27. The left end portions of the first electrode portion 40 and the second electrode portion 45 are located near the left end portion of the main body portion 27. Further, each of the plurality of heater wire portions 51, 55 is formed between the first electrode portion 40 and the second electrode portion 45, and is connected to the first electrode portion 40 at the first end portions 53, 58 and to the second electrode portion 45 at the second end portions 54, 62. Thus, the plurality of heater wire portions 51, 55 are formed in a wide area of the film base material 26. Therefore, a wide area of the heater film 25 can be heated.

[0093] (2-2) Also, since the plurality of heater wire portions 51, 55 are connected in parallel to the first electrode portion 40 and the second electrode portion 45, the same voltage is applied to each of the heater wire portions 51, 55. Therefore, each of the heater wire portions 51, 55 can be heated uniformly.

[0094] (2-3) Further, for each of the first electrode portion 40 and the second electrode portion 45, since the actual line width and the substantial line width are larger than the line width of the heater wire portions 51, 55, the resistance of each of the first electrode portion 40 and the second electrode portion 45 is smaller than the resistance of the heater wire portions 51, 55. Accordingly, even if the first electrode portion 40 and the second electrode portion 45 generate heat, they do not generate as much heat as the heater wire portions 51, 55. Therefore, it becomes easier to heat the heater film 25 with a uniform heat generation distribution by the heater wire portions 51, 55.

[0095] (2-4) In the present embodiment, the adjacent straight portions 52, 56 extend in the facing direction in a state of being parallel to each other and spaced apart in the intersecting direction. The interval between the adjacent straight portions 52, 56 is uniform in the facing direction. Therefore, compared with the case where the interval is different in the facing direction, heat can be generated between the adjacent straight portions 52, 56 with a uniform heat generation distribution in the facing direction.

[0096] (2-5) In this embodiment, the straight portions 52 and 56 are formed at regular intervals in the above-mentioned crossing direction. Therefore, the intervals between adjacent straight portions 52 and 56 are uniform in the above-mentioned crossing direction. Accordingly, compared with the case where the intervals are different in the above-mentioned crossing direction, it becomes easier to cause the heater film 25 to generate heat with a uniform heat generation distribution in the above-mentioned crossing direction.

[0097] (2-6) The first electrode portion 40 and the second electrode portion 45 are curved so as to bulge toward the side where they move away from each other. Therefore, among the plurality of straight portions 52 and 56, the one located at the central portion in the above-mentioned crossing direction becomes the longest. The length of the straight portions 52 and 56 becomes shorter as it moves away from the central portion in the above-mentioned crossing direction. As the length becomes shorter, the calorific value of the straight portions 52 and 56 decreases. The heat generation has a distribution in which the calorific value is large at the central portion in the above-mentioned crossing direction and decreases as it moves away from the central portion in the above-mentioned crossing direction.

[0098] In this regard, in this embodiment, the heater wire portions 55 located on both side portions in the above-mentioned crossing direction are composed of the straight portion 56, the first extension portion 57, and the second extension portion 61. The heater wire portions 55 on both side portions are longer by the lengths of the first extension portion 57 and the second extension portion 61 compared with the case where they are composed of only the straight portion 56, that is, compared with the case where the whole extends linearly in the above-mentioned facing direction.

[0099] By being lengthened as described above, the calorific value of the heater wire portion 55 increases. Accordingly, the variation in the heat generation distribution in the above-mentioned crossing direction can be reduced. Further, in this embodiment, the total length of the heater wire portion 55 is made close to the length of the longest one located at the central portion in the above-mentioned crossing direction. Therefore, the variation in the above-mentioned heat generation distribution can be made even smaller.

[0100] In particular, as described above, among the heater wire portions 55, the straight portion 56 becomes shorter as it is farther from the central portion in the intersecting direction. However, among the heater wire portions 55, the first extension portion 57 and the second extension portion 61 become longer as they are farther from the central portion in the intersecting direction. Therefore, for any of the heater wire portions 55, the total length can be made close to the length of the longest heater wire portion 51.

[0101] (2-7) In the right half of the main body portion 27, current can flow from the first electrode portion 40 through the heater wire portions 51 and 55 toward the second electrode portion 45. In the left half of the main body portion 27, current can flow from the second electrode portion 45 through the heater wire portions 51 and 55 toward the first electrode portion 40.

[0102] Therefore, current can flow evenly through the entire plurality of heater wire portions 51 and 55. The heater film 25 can generate heat with a more uniform heat generation distribution. By the way, when visible light is irradiated on the millimeter-wave transmission cover 20 shown in FIG. 2 from the front of the vehicle 10, the visible light passes through the transparent protection portion 70 and is irradiated on the heater film 25. The visible light passes through the main body portion 27 of the film base material 26. The visible light irradiated on the portions where the first electrode portion 40, the second electrode portion 45, and the heater wire portions 51 and 55 are not formed passes through. The visible light irradiated on the first electrode portion 40, the second electrode portion 45, and the heater wire portions 51 and 55 is reflected.

[0103] <Improvement in the appearance of the millimeter-wave transmission cover 20> (3-1) As described in (2-2) above, a plurality of heater wire portions 51 and 55 are connected in parallel to the first electrode portion 40 and the second electrode portion 45 (see FIG. 3). From this, it is possible to reduce the line width of each heater wire portion 51 and 55 compared to the case where the heater wire portions 51 and 55 are connected in series to the first electrode portion 40 and the second electrode portion 45. Also, by increasing the number of heater wire portions 51 and 55, it is possible to reduce the line width of each heater wire portion 51 and 55.

[0104] As the line widths of the heater line portions 51 and 55 become smaller, the heater line portions 51 and 55 become more difficult to visually recognize. Therefore, the appearance of the heater film 25 and thus the millimeter-wave transmission cover 20 can be improved.

[0105] (3-2) As shown in FIG. 3, since the first positive electrode portion 41, the first negative electrode portion 42, and the second electrode portion 45 are formed at the edge portion 28 of the main body portion 27, they are less conspicuous than when they are formed inward in the radial direction from the edge portion 28. Therefore, the appearance of the millimeter-wave transmission cover 20 is further improved.

[0106] (3-3) In the present embodiment, as shown in FIGS. 11 to 13, slits 43 and 46 extending in the above-described crossing direction along the edge portion 28 are formed in each of the first electrode portion 40 and the second electrode portion 45. The first electrode portion 40 and the second electrode portion 45 are less conspicuous than those in which the slits 43 and 46 are not formed. Therefore, also in this regard, the appearance of the millimeter-wave transmission cover 20 is further improved.

[0107] (3-4) As shown in FIG. 3, the adjacent straight portions 52 and 56 extend in the above-described facing direction in a state of being spaced apart from each other in parallel in the above-described crossing direction. The interval between the adjacent straight portions 52 and 56 is uniform in the above-described facing direction. Therefore, the straight portions 52 and 56 are less conspicuous than when the interval varies in the above-described facing direction. Therefore, also in this regard, the appearance of the millimeter-wave transmission cover 20 is improved.

[0108] (3-5) As shown in FIG. 3, a plurality of straight portions 52 and 56 are formed at regular intervals in the above-described crossing direction. Therefore, the plurality of straight portions 52 and 56 are evenly arranged in the above-described crossing direction, and the straight portions 52 and 56 are less conspicuous than when the interval between the adjacent straight portions 52 and 56 varies in the crossing direction. Also in this regard, the appearance of the millimeter-wave transmission cover 20 is improved.

[0109] As shown in Fig. 3 ((3-6)), the heater wire portions 55 located on both sides in the above-mentioned crossing direction are composed of a straight portion 56, a first extension portion 57, and a second extension portion 61. The first extension portion 57 extends from the lower end portion of the straight portion 56 toward the first electrode portion 40. The second extension portion 61 extends from the upper end portion of the straight portion 56 toward the second electrode portion 45.

[0110] Therefore, with the formation of the first extension portion 57, the first electrode portion 40 becomes shorter, and accordingly, the first electrode portion 40 becomes less conspicuous, further improving the appearance. Also, with the formation of the second extension portion 61, the second electrode portion 45 becomes shorter, and accordingly, the second electrode portion 45 becomes less conspicuous, further improving the appearance.

[0111] According to this embodiment, in addition to the above, the following effects can be obtained. (4-1) If the slit 43 is not formed in the first electrode portion 40 and the slit 46 is not formed in the second electrode portion 45, the following phenomenon may occur. That is, the rigidity difference between the portions where the first electrode portion 40 and the second electrode portion 45 are formed and the portions where they are not formed in the heater film 25 becomes large. Among the heater film 25, the portions where the first electrode portion 40 and the second electrode portion 45 are formed are difficult to be bent and deformed.

[0112] In this regard, in this embodiment, as shown in Figs. 11 to 13, a slit 43 extending in the above-mentioned crossing direction along the lower portion 28L is formed in the first electrode portion 40, and a slit 46 extending in the above-mentioned crossing direction along the upper portion 28U is formed in the second electrode portion 45.

[0113] Therefore, the rigidity difference between the portions where the first electrode portion 40 and the second electrode portion 45 are formed and the portions where they are not formed in the heater film 25, particularly the rigidity difference between the first electrode portion 40 and the second electrode portion 45 and the surrounding portions, becomes small.

[0114] Therefore, the portions where the first electrode portion 40 and the second electrode portion 45 are formed in the heater film 25 can be easily bent. (4-2) If the heater wire portions 51 and 55 are connected in series to the first positive electrode portion 41 and the first negative electrode portion 42, the heater wire portions 51 and 55 will have the following configuration, for example. That is, the heater wire portions 51 and 55 are composed of a plurality of straight portions and arc-shaped connecting portions that connect the ends of adjacent straight portions to each other.

[0115] However, in this case, the connecting portion has to be formed at a location radially inwardly away from the edge portion 28 of the cover main body portion 21, and accordingly, the heat-generating region becomes smaller. In this regard, in the present embodiment, as shown in FIG. 3, the first positive electrode portion 41, the first negative electrode portion 42, and the second electrode portion 45 are formed behind the edge portion 28 of the main body portion 27. The straight portion 52 of the heater wire portion 51 is extended to the lower portion 28L and connected to the first electrode portion 40, and is also extended to the upper portion 28U and connected to the second electrode portion 45.

[0116] Also, the straight portion 56 of the heater wire portion 55 is extended to the lower portion 28L and connected to the first electrode portion 40 via a first extension portion 57 extending along the lower portion 28L. The straight portion 56 is extended to the upper portion 28U and connected to the second electrode portion 45 via a second extension portion 61 extending along the upper portion 28U.

[0117] Thus, since the straight portions 52 and 56 extend to the lower portion 28L and the upper portion 28U, the heat-generating region becomes larger compared to the case of connecting in series as described above. (4-3) As shown in FIGS. 10, 13, and 14, in the present embodiment, the positive terminal portion 33 and the negative terminal portion 34 are formed in a net shape.

[0118] Therefore, when receiving an external force, the positive terminal portion 33 and the negative terminal portion 34 are likely to bend or deform. Accordingly, by receiving the above force, it is possible to suppress the positive terminal portion 33 and the negative terminal portion 34 from cracking or the like.

[0119] Note that the above-described embodiment can also be implemented as a modified example in which it is changed as follows. The above-described embodiment and the following modified examples can be implemented in combination with each other within a technically non-conflicting range.

[0120] <Regarding the shape of the cover main body 21> · In FIG. 1, the shape of the cover main body 21 as viewed from the front may be changed to a shape different from that of the above-described embodiment, for example, a circular shape, a polygonal shape, or the like.

[0121] <Regarding the layer structure of the heater film 25> · In FIG. 2, the adhesive layer 31 may be formed on the front surface of the film base material 26, and the conductive portion 32 may be formed on the front surface of the adhesive layer 31. In this case, the film base material 26 may be formed of a non-transparent resin material.

[0122] <Regarding the position of the connection portion 29> · In FIGS. 3 and 10, the connection portion 29 may extend from a portion different from that of the above-described embodiment, for example, the upper portion, the side portion, the lower portion, etc. at the edge portion 28 of the main body portion 27.

[0123] When the connection portion 29 extends downward from the above-described central portion 28C, the narrow portion 41a becomes unnecessary for the first plus electrode portion 41, and the narrow portion 42a becomes unnecessary for the first minus electrode portion 42. The first plus electrode portion 41 and the first minus electrode portion 42 are not adjacent to each other in the above-described radial direction, and are adjacent only in the direction along the lower portion 28L (circumferential direction).

[0124] <Regarding the first electrode portion 40 and the second electrode portion 45> · In FIG. 3, the first electrode portion 40 and the second electrode portion 45 may be arranged in a state of facing each other in a direction different from the vertical direction on the condition that they are outside the transmission region Z1. For example, the first electrode portion 40 and the second electrode portion 45 may be arranged in a state of facing each other in the left-right direction, or may be arranged in a state of facing each other in a direction along a line that obliquely intersects the vertical line or the horizontal line.

[0125] In these cases, along with the above-described changes, the direction in which the straight portions 52 and 56 of the heater wire portions 51 and 55 extend may also be changed to the above-described opposing direction. · Contrary to the above-described embodiment, the right side portion of the first electrode portion 40 may be constituted by the first negative electrode portion 42, and the left side portion may be constituted by the first positive electrode portion 41. Along with this, the negative terminal portion 34 is provided at the right side portion of the connection portion 29, and the positive terminal portion 33 is provided at the left side portion of the connection portion 29.

[0126] In this case, the direction of the current flow becomes opposite to that in the above-described embodiment. That is, in the left half of the heater film 25, the current flows from the first electrode portion 40 toward the second electrode portion 45, and in the right half of the heater film 25, the current flows from the second electrode portion 45 toward the first electrode portion 40.

[0127] · In FIGS. 12 and 13, the slit 43 in at least one of the first positive electrode portion 41 and the first negative electrode portion 42 may be omitted. Similarly, in FIG. 11, the slit 46 of the second electrode portion 45 may be omitted.

[0128] · A part of the edge portion 28 of the main body portion 27 may be formed in a straight line shape, and a portion of the edge portion 28 that faces the above-described part may be curved so as to bulge toward the side away from the same part. In this case, the shapes of the first electrode portion 40 and the second electrode portion 45 are also changed. That is, one of the first electrode portion 40 and the second electrode portion 45 is formed in a straight line shape, and the other is formed in a shape that curves so as to bulge toward the side away from the above-described one.

[0129] <Regarding the heater wire portions 51 and 55> · The straight portions 52 and 56 of the heater wire portions 51 and 55 may extend in a direction inclined with respect to the above-described opposing direction.

[0130] · The number of the heater wire portions 55 for each side portion may be changed to a number different from that in the above-described embodiment. The minimum number is 0. Along with this change, the total number of the heater wire portions 51 and 55 changes. Under the condition that the total number of the heater wire portions 51 and 55 remains unchanged, when the number of the heater wire portions 55 is changed, the heater wire portions 55 to be changed are replaced with the heater wire portions 51.

[0131] · The length of the heater wire portion 55 may be increased by a method different from that of the above embodiment. In the modification shown by the two-dot chain line in FIGS. 4 and 5, the straight portion 56 of the heater wire portion 55 is changed to a non-straight portion 85 that extends in the above-mentioned opposite direction while meandering, which can be described as swaying in both directions of the above-mentioned crossing direction.

[0132] Also, in the modification shown by the two-dot chain line in FIGS. 8 and 9, the straight portion 56 of the heater wire portion 55 is changed to a so-called zigzag non-straight portion 86 that is repeatedly bent in the above-mentioned crossing direction.

[0133] In any of the above modifications, the non-straight portions 85 and 86 are longer than the straight portion 56. In addition, as described above, when the non-straight portions 85 and 86 are set in the heater wire portion 55, it is desirable to design so that the influence on the millimeter wave transmissivity and the appearance is small.

[0134] Also, in the above design, it is desirable to design so that the length of the heater wire portion 55 having the non-straight portions 85 and 86 approaches the length of the longest one among the plurality of heater wire portions 51, that is, the one located at the central portion in the crossing direction.

[0135] As described above, since the heater wire portion 55 has the non-straight portions 85 and 86, when a force acting outward in the above-mentioned opposite direction from the outside is applied to the cover main body portion 21 when the millimeter wave transmission cover 20 is used, the following effects can be expected. That is, due to the above force, the non-straight portions 85 and 86 are pulled and deformed. However, the non-straight portions 85 and 86 are unlikely to reach a fully extended state, and excessive tension applied to the non-straight portions 85 and 86 can be suppressed.

[0136] ·In FIGS. 8 and 9, at least one of the first extension portion 57 and the second extension portion 61 may be formed linearly instead of arcuately. ·Regarding at least one of the first extension portion 57 and the second extension portion 61, it may also be formed in a meandering shape or a zigzag shape, similar to the non-linear portions 85 and 86.

[0137] ·Regarding the heater wire portion 51 as well, similar to the non-linear portions 85 and 86 of the heater wire portion 55, the linear portion 52 may be changed to a non-linear portion forming a meandering shape or a zigzag shape. ·For the purpose of equalizing the heat generation distribution, the interval between the linear portions 52 and 56 may be maximized at the central portion in the crossing direction and decreased as the distance from the central portion increases.

[0138] Also, in the middle portion in the crossing direction, the interval may be made constant in the same direction, and in the side portion in the crossing direction, the interval may be made smaller than that in the middle portion. <Regarding the entire conductive portion 32> ·The conductive portion 32 may be formed by patterning a metal film such as copper or silver formed by plating through etching.

[0139] <Regarding the layer structure of the millimeter-wave transmission cover 20> The millimeter-wave transmission cover 20 has a layer structure in which a plurality of layers including the heater film 25 are laminated in the front-rear direction. The layer configuration in this layer structure may be changed, for example, as follows.

[0140] ·When the film base material 26 has a sufficient thickness to protect the conductive portion 32 and the like, the protective portion 70 can be omitted. ·If the resist layer 65 is not necessary, the resist layer 65 may be formed by the binder layer 67. In other words, in FIG. 2, the portion illustrated by the resist layer 65 and the binder layer 67 may be constituted only by the binder layer 67.

[0141] · The binder layer 67 is provided as an adhesive layer that adheres the cover base material 23 to the heater film 25 when resin-molding the cover base material 23 on the rear side of the heater film 25. A similar adhesive layer can also be formed by the above OCA. In this case, the resist layer 65 and the binder layer 67 may be replaced by OCA.

[0142] · In the layer structure, the number of layers different from the heater film 25 may be changed to a number different from that in the above embodiment. · A new layer may be added for adding functions.

[0143] When a layer is added in front of the heater film 25, the layer is formed of a transparent resin material so that the heater film 25 can be seen through the same layer from outside the vehicle 10.

[0144] When a layer is added behind the heater film 25, the layer may be transparent or opaque. <Others> · The above millimeter-wave transmission cover 20 can be embodied in an emblem, ornament, mark, etc. of the vehicle 10.

[0145] · The above electromagnetic wave transmission cover is applicable to any vehicle equipped with a device for transmitting and receiving electromagnetic waves for detecting an object outside the vehicle. In this case, the electromagnetic waves transmitted and received by the device include electromagnetic waves such as near-infrared rays in addition to millimeter waves.

[0146] · The device for transmitting and receiving electromagnetic waves for detecting an object outside the vehicle may be a device for rear monitoring, front side monitoring, or rear side monitoring in addition to the front monitoring. In this case, the electromagnetic wave transmission cover is disposed in front of the above device in the electromagnetic wave transmission direction.

[0147] · The electromagnetic wave transmission cover is also applicable when the device for transmitting and receiving electromagnetic waves is mounted on a vehicle of a different type from the vehicle, for example, an aircraft, a ship, etc.

Explanation of Signs

[0148] 10… Vehicle (automobile) 13… Millimeter-wave radar device (device) 20… Millimeter-wave transmission cover (electromagnetic wave transmission cover) 25… Heater film 32… Conductive part 33… Positive terminal part 34… Negative terminal part 40… First electrode part 41… First positive electrode part 42… First negative electrode part 43,46… Slit 45… Second electrode part 51,55… Heater wire part 52,56… Straight part 53,58… First end 54,62… Second end 57… First extension 61… Second extension 82… Equipment Z1… Transmission area

Claims

1. Applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, disposed in front of the device in the transmission direction of the electromagnetic waves, and having a layer structure in which a plurality of layers are laminated in the transmission direction, and an electromagnetic wave transmission cover in which one of the plurality of layers is constituted by a heater film, the heater film includes a conductive portion formed of a conductive material, the conductive portion includes a plurality of heater wire portions, a first electrode portion, and a second electrode portion, the first electrode portion and the second electrode portion are located outside the transmission region of the electromagnetic waves and face each other across the transmission region, when the direction in which the first electrode portion and the second electrode portion face each other is defined as the facing direction and the direction intersecting the facing direction is defined as the intersecting direction, the first electrode portion and the second electrode portion each extend in the intersecting direction, each of the plurality of heater wire portions has a first end portion and a second end portion, the first end portion of each heater wire portion is connected to the first electrode portion, and the second end portion of each heater wire portion is connected to the second electrode portion, furthermore, the first electrode portion and the second electrode portion have a line width larger than the line width of the heater wire portion, an electromagnetic wave transmission cover in which a slit extending in the intersecting direction is formed in each of the first electrode portion and the second electrode portion.

2. Applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, disposed in front of the device in the transmission direction of the electromagnetic waves, and having a layer structure in which a plurality of layers are laminated in the transmission direction, and an electromagnetic wave transmission cover in which one of the plurality of layers is constituted by a heater film, the heater film includes a conductive portion formed of a conductive material, the conductive portion includes a plurality of heater wire portions, a first electrode portion, and a second electrode portion, the first electrode portion and the second electrode portion are located outside the transmission region of the electromagnetic waves and face each other across the transmission region, when the direction in which the first electrode portion and the second electrode portion face each other is defined as the facing direction and the direction intersecting the facing direction is defined as the intersecting direction, the first electrode portion and the second electrode portion each extend in the intersecting direction, each of the plurality of heater wire portions has a first end portion and a second end portion, the first end portion of each heater wire portion is connected to the first electrode portion, and the second end portion of each heater wire portion is connected to the second electrode portion, furthermore, the first electrode portion and the second electrode portion have a line width larger than the line width of the heater wire portion, Among the plurality of the heater wire portions, each of the plurality of the heater wire portions located at at least the intermediate portion in the crossing direction is constituted by a straight portion that linearly extends in the facing direction as a whole. The straight portion for each of the plurality of the heater wire portions located at at least the intermediate portion in the crossing direction extends in the facing direction in a state of being spaced apart from each other in parallel in the crossing direction, and is an electromagnetic wave transmission cover.

3. The electromagnetic wave transmission cover according to claim 2, wherein in the plurality of the heater wire portions located at at least the intermediate portion in the crossing direction, the straight portions are formed at regular intervals in the crossing direction.

4. One of the first electrode portion and the second electrode portion is curved so as to bulge toward the side away from the other, and the other is curved so as to bulge toward the side away from the one. The electromagnetic wave transmission cover according to claim 2 or 3, wherein among the plurality of the heater wire portions, the heater wire portions located on both side portions in the crossing direction are formed longer than the case where they linearly extend in the facing direction as a whole.

5. The heater wire portions located on both side portions in the crossing direction include a straight portion that linearly extends in the facing direction outside the first electrode portion and the second electrode portion in the crossing direction, a first extension portion that extends from one end of the straight portion toward the first electrode portion and has the first end portion, and a second extension portion that extends from the other end of the straight portion toward the second electrode portion and has the second end portion, and the first extension portion is connected to the first electrode portion at the first end portion, and the second extension portion is connected to the second electrode portion at the second end portion. The electromagnetic wave transmission cover according to claim 4.

6. An electromagnetic wave transmission cover applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, disposed in front of the device in the transmission direction of the electromagnetic waves, and having a layer structure in which a plurality of layers are laminated in the transmission direction, and one of the plurality of layers is constituted by a heater film, wherein the heater film includes a conductive portion formed of a conductive material, the conductive portion includes a plurality of heater wire portions, a first electrode portion, and a second electrode portion, and the first electrode portion and the second electrode portion are located outside the transmission region of the electromagnetic waves and face each other with the transmission region therebetween. When the direction in which the first electrode portion and the second electrode portion face each other is defined as the facing direction, and the direction intersecting the facing direction is defined as the intersecting direction, the first electrode portion and the second electrode portion each extend in the intersecting direction. Each of the plurality of heater wire portions has a first end portion and a second end portion. The first end portion of each heater wire portion is connected to the first electrode portion, and the second end portion of each heater wire portion is connected to the second electrode portion. Furthermore, the first electrode portion and the second electrode portion have a line width larger than the line width of the heater wire portion. The conductive portion further includes a plus terminal portion and a minus terminal portion to which equipment for power supply is connected. The first electrode portion includes a first plus electrode portion connected to the plus terminal portion and a first minus electrode portion formed in a state of being separated from the first plus electrode portion and connected to the minus terminal portion. The first plus electrode portion and the first minus electrode portion are adjacent to each other at least in a state of being separated in the intersecting direction. The second electrode portion faces the first plus electrode portion and the first minus electrode portion as an intermediate electrode portion between the first plus electrode portion and the first minus electrode portion. An electromagnetic wave transmission cover in which the first end portion of a part of the heater wire portion is connected to the first plus electrode portion, the second end portion of the part of the heater wire portion is connected to the second electrode portion, the first end portion of the remaining heater wire portion is connected to the first minus electrode portion, and the second end portion of the remaining heater wire portion is connected to the second electrode portion.

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