JP7682724B2 - Electromagnetic wave transparent cover - Google Patents

Description

The present invention relates to an electromagnetic wave transparent cover that covers a device that transmits and receives electromagnetic waves such as millimeter waves from the front in the electromagnetic wave transmission direction.

In vehicles equipped with a device for transmitting and receiving electromagnetic waves such as millimeter waves, the device transmits electromagnetic waves toward the outside of the vehicle. Electromagnetic waves that are reflected by objects outside the vehicle, including preceding vehicles and pedestrians, are received by the device. The device then recognizes the objects based on the transmitted and received electromagnetic waves, and detects the distance and relative speed between the vehicle and the object, etc.

In the vehicle, an electromagnetic wave transparent cover that transmits electromagnetic waves is disposed in front of the device in the transmission direction of the electromagnetic waves. The electromagnetic wave transparent cover has a layered structure in which multiple layers are stacked in the transmission direction, and covers the device from the front in the transmission direction.

However, if ice or snow adheres to the electromagnetic wave-transmitting cover, the electromagnetic waves are attenuated, resulting in a problem in that the detection performance of the device is reduced. As a result, an electromagnetic wave-transmitting cover with an added heater film has been proposed (see, for example, Patent Document 1).

The heater film has a conductive portion formed of a conductive material. The conductive portion has an electrode portion and a heater wire portion connected to the electrode portion. The heater wire portion has a plurality of straight portions arranged spaced apart from each other, and an arc-shaped connecting portion connecting the ends of adjacent straight portions.

With the electromagnetic wave transparent cover, when power is supplied to the conductive part, the heater wire part generates heat. Therefore, even if ice and snow adhere to the electromagnetic wave transparent cover, the heat generated by the heater wire part melts the ice and snow, making it possible to suppress the attenuation of electromagnetic waves caused by the adhesion of ice and snow.

Patent No. 6719506

However, in the electromagnetic wave transparent cover described in Patent Document 1, if the electrode portion has a line width similar to that of the heater wire portion, there is a risk that the electrode portion will generate heat in the same way as the heater wire portion when electricity is passed through it. In this case, it is difficult to generate heat with a uniform heat distribution in the area of the heater film that is desired to be heated. Also, in the electromagnetic wave transparent cover described in Patent Document 1, the line width of the heater wire portion is large at 50 μm to 70 μm, so the heater wire portion is easily visible, which also causes a problem of degraded appearance.

The electromagnetic wave transparent cover that solves the above problem is applied to a vehicle equipped with a device that transmits and receives electromagnetic waves, is arranged in front of the device in the transmission direction of the electromagnetic waves, and has a layered structure in which multiple layers are stacked in the transmission direction, and one of the multiple layers is composed of a heater film, and the heater film has a conductive portion formed of a conductive material, and the conductive portion has multiple 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 area of the electromagnetic waves, and the conductive portion is configured to have a conductive portion formed of a conductive material. The heater wire portions are located at opposing positions across an area, and when the direction in which the first electrode portion and the second electrode portion face each other is defined as an opposing direction and the direction that intersects with the opposing direction is defined as an intersecting direction, the first electrode portion and the second electrode portion each extend in the intersecting direction, and each of the heater wire portions has a first end and a second end, the first end of each heater wire portion is connected to the first electrode portion, and the second end of each heater wire portion is connected to the second electrode portion, and further, the first electrode portion and the second electrode portion have a line width larger than the line width of the heater wire portion.

According to the above configuration, when a current flows through the conductive portion of the electromagnetic wave transmission cover in the order of the first electrode portion, the multiple heater wire portions, and the second electrode portion, or vice versa, when a current flows through the second electrode portion, the multiple heater wire portions, and the first electrode portion, each heater wire portion generates heat.

Here, the first electrode portion and the second electrode portion are located outside the electromagnetic wave transmission area, facing each other across the transmission area, and extend in a cross direction that crosses the facing direction. Each of the multiple heater wire portions is formed between the first electrode portion and the second electrode portion, and is connected to the first electrode portion at a first end and to the second electrode portion at a second end. In this way, the multiple heater wire portions are formed over a wide area. This makes it possible to generate heat over a wide area of the heater film.

In addition, since the multiple heater wire sections are connected in parallel to the first electrode section and the second electrode section, the same voltage is applied to each heater wire section. Therefore, it is possible to cause each heater wire section to generate heat uniformly.

Furthermore, since the line width of each of the first electrode portion and the second electrode portion is larger than the line width of the heater wire portion, the resistance of each of the first electrode portion and the second electrode portion is smaller than the resistance of the heater wire portion. Even if the first electrode portion and the second electrode portion generate heat, they do not generate as much heat as the heater wire portion. Therefore, it is possible to heat the heater film with a uniform heat distribution by the heater wire portion.

In addition, it is possible to make the line width of each heater wire smaller than when the heater wires are connected in series to the first electrode portion and the second electrode portion. Also, by increasing the number of heater wires, it is possible to make the line width of each heater wire smaller.

As the line width of the heater wire portion becomes smaller, the heater wire portion becomes less visible, improving the appearance of the heater film and, in turn, the electromagnetic wave transparent cover.
In the electromagnetic wave transmission cover, it is preferable that each of the first electrode portion and the second electrode portion has a slit formed therein, the slit extending in the intersecting direction.

According to the above configuration, the formation of the slits makes the first electrode portion and the second electrode portion less noticeable compared to a case where no slits are formed, further improving the appearance.
In addition, the difference in rigidity between the heater film where the first and second electrode portions are formed and the heater film where they are not formed, particularly the first and second electrode portions and their surrounding areas, is small, so that the heater film can be easily bent at the heater film where the first and second electrode portions are formed.

In the electromagnetic wave transmission cover, among the plurality of heater wire sections, each of the plurality of heater wire sections located at least in the middle in the intersecting direction is preferably configured with a straight line section that extends linearly in the opposing direction as a whole, and the straight line section of each of the plurality of heater wire sections located at least in the middle in the intersecting direction preferably extends in the opposing direction while being spaced apart and parallel to each other in the intersecting direction.

According to the above configuration, in the multiple heater wire sections located at least in the middle in the crossing direction, the intervals between adjacent straight sections are uniform in the opposing direction. Therefore, compared to a case where the intervals vary in the opposing direction, it is possible to generate heat with a uniform heat distribution between adjacent straight sections in the opposing direction.

Moreover, the straight line portions are less likely to be visually recognized than when the intervals between adjacent straight line portions are different in the opposing direction.
In the electromagnetic wave transmission cover, it is preferable that, in the plurality of heater wire portions located at least in a middle portion in the intersecting direction, the straight line portions are formed at regular intervals in the intersecting direction.

According to the above configuration, in the multiple heater wire sections located at least in the middle in the crossing direction, the spacing between adjacent straight line sections is uniform in the crossing direction. Therefore, it is easier to generate heat from the heater film with a uniform heat distribution in the crossing direction compared to when the spacing between adjacent straight line sections varies in the crossing direction.

Furthermore, since the straight line portions are arranged evenly in the intersecting direction, the heater wire portion is less likely to be visually recognized than when the intervals between adjacent straight line portions are different in the intersecting direction.
In the above-mentioned electromagnetic wave transmission cover, one of the first electrode portion and the second electrode portion is curved so as to bulge away from the other, and the other is curved so as to bulge away from the one, and it is preferable that, among the multiple heater wire portions, the heater wire portions located on both sides in the intersecting direction are formed longer than when the entire portion extends linearly in the opposing direction.

When the first electrode portion and the second electrode portion are curved as described above, the distance between the two electrodes is widest at the center in the intersecting direction. The distance becomes narrower as the distance from the center increases in the intersecting direction.

As a result, the straight line portion of the heater wire is longer in the center in the intersecting direction than in other portions. The length of the straight line portion becomes shorter as it moves away from the center in the intersecting direction. As the length becomes shorter, the amount of heat generated by the heater wire decreases. The amount of heat generated is distributed so that the amount of heat generated is large in the center in the intersecting direction and decreases as it moves away from the center in the intersecting direction.

In this regard, according to the above configuration, among the multiple heater wire portions, the heater wire portions located on both sides in the intersecting direction are formed to be longer than when the entire heater wire portions extend linearly in the opposing direction. By making them longer as described above, the amount of heat generated by the heater wire portions on both sides increases. This reduces the variation in heat generation distribution in the intersecting direction.

In the electromagnetic wave transmission cover, the heater wire portions located on both sides in the intersecting direction are preferably composed of a straight portion extending linearly in the opposing direction outside the first electrode portion and the second electrode portion in the intersecting direction, a first extension portion extending from one end of the straight portion toward the first electrode portion and having the first end, and a second extension portion extending from the other end of the straight portion toward the second electrode portion and having the second end, and the first extension portion is connected to the first electrode portion at the first end, and the second extension portion is connected to the second electrode portion at the second end.

According to the above configuration, the heater wire portions located on both sides in the intersecting direction are composed of a straight portion, a first extension portion, and a second extension portion. The heater wire portions on both sides are longer by the amount of the first extension portion and the second extension portion compared to when the heater wire portions are composed only of straight portions.

Furthermore, with the formation of the first extension portion, the length of the first electrode portion in the intersecting direction is shortened. This makes the first electrode portion less noticeable, further improving the appearance. Furthermore, with the formation of the second extension portion, the length of the second electrode portion in the intersecting direction is shortened. This makes the second electrode portion less noticeable, further improving the appearance.

In the electromagnetic wave transmission cover, the conductive portion further includes a positive terminal portion and a negative terminal portion to which a device for supplying power is connected, and the first electrode portion includes a first positive electrode portion connected to the positive terminal portion and a first negative electrode portion formed in a state spaced apart from the first positive electrode portion and connected to the negative terminal portion, the first positive electrode portion and the first negative electrode portion are adjacent to each other in a state spaced apart at least in the intersecting direction, the second electrode portion faces the first positive electrode portion and the first negative electrode portion as a relay electrode portion between the first positive electrode portion and the first negative electrode portion, and the first end portion of a part of the heater wire portion is connected to the first positive electrode portion, the second end portion of a 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 negative electrode portion, and the second end portion of the remaining heater wire portion is connected to the second electrode portion.

According to the above configuration, when power is supplied from the device to the conductive part, a current flows in the order of the positive terminal part, the first positive electrode part, the heater wire parts connected to the first positive electrode part, and the second electrode part. The current also flows in the order of the second electrode part, the heater wire parts connected to the first negative electrode part, the first negative electrode part, and the negative terminal part. The direction of the current flowing from the first positive electrode part to the second electrode part is opposite to the direction of the current flowing from the second electrode part to the first negative electrode part.

This allows current to flow evenly throughout the multiple heater wire sections. This allows the heater film to generate heat with a more uniform heat distribution.

The electromagnetic wave transparent cover described above makes it possible to achieve both uniform heat distribution and improved appearance.

FIG. 2 is a partial front view showing an embodiment in which the electromagnetic wave transparent cover is embodied as a millimeter wave transparent cover for a vehicle, together with a part of the front grille. FIG. 2 is a partial cross-sectional plan view showing the millimeter wave transparent cover of the embodiment together with a part of the millimeter wave radar device. FIG. 4 is a rear view of the heater film of the embodiment, showing a state before a resist layer is formed. FIG. 4 is an enlarged partial rear view of part A in FIG. 3 . FIG. 4 is an enlarged partial rear view of part B in FIG. 3 . FIG. 4 is an enlarged partial rear view of part C in FIG. 3 . FIG. 4 is an enlarged partial rear view of part D in FIG. 3 . FIG. 4 is an enlarged partial rear view of part E in FIG. 3 . FIG. 4 is an enlarged partial rear view of part F in FIG. 3 . FIG. 4 is an enlarged partial rear view of part G in FIG. 3 . FIG. 7 is an enlarged partial rear view of part H in FIG. 6 . FIG. 8 is an enlarged partial rear view of part I in FIG. 7 . FIG. 11 is an enlarged partial rear view of a portion J in FIG. 10 . FIG. 11 is an enlarged partial rear view showing a portion K in FIG. 10 .

Hereinafter, an embodiment in which an electromagnetic wave transparent cover is embodied as a millimeter wave transparent cover for a vehicle will be described with reference to the drawings.
In the following description, the forward direction of the vehicle is referred to as the front, and the backward direction is referred to as the rear. The up-down direction refers to the up-down direction of the vehicle, and the left-right direction refers to the width direction of the vehicle, which corresponds to the left-right direction when the vehicle is moving forward. Furthermore, in FIG. 2, the scale of each part of the millimeter wave transmitting cover is appropriately changed so that each part can be recognized.

As shown in Figures 1 and 2, a millimeter wave radar device 13 for monitoring the front is mounted behind the front grille 11 in the center of the front of the vehicle 10 in the left-right direction as a device for transmitting and receiving electromagnetic waves. In Figure 2, only a part of the millimeter wave radar device 13 is shown. The millimeter wave radar device 13 has the function of transmitting millimeter waves, which are electromagnetic waves, toward the front outside the vehicle, and receiving millimeter waves reflected by objects outside the vehicle. Millimeter waves are radio waves with a wavelength of 1 mm to 10 mm and a frequency of 30 GHz to 300 GHz.

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

The thickness of the front grill 11 is not constant, as with a typical front grill. In addition, in the front grill 11, a metal plating layer may be formed on the surface of the resin base material. The front grill 11 may interfere with the transmitted or reflected millimeter waves. For this reason, the front grill 11 has a window 12 opened in front of the millimeter wave radar device 13 in the transmission direction of the millimeter waves, and a millimeter wave transparent cover 20 is disposed in this window. The millimeter wave transparent cover 20 covers the millimeter wave radar device 13 from the front.

The main part of the millimeter wave transmitting cover 20 is composed of the cover body 21. In FIG. 2, only a part of the cover body 21 is shown. When viewed from the front, the cover body 21 has an elliptical shape with a larger dimension in the left-right direction than in the up-down direction. The cover body 21 is positioned in an upright position with its front surface facing forward and its rear surface facing backward. The front surface of the cover body 21 constitutes the design surface 22.

A part of the area spaced inward from the outer peripheral edge of the cover body 21 is defined as a transmission area Z1 for millimeter waves transmitted from the millimeter wave radar device 13 (see FIG. 3).
The cover body 21 has a layered structure in which a plurality of layers are laminated in the front-rear direction. The plurality of layers includes a cover base material 23, a heater film 25, and a protective portion 70. Next, each layer will be described.

<Cover substrate 23>
The cover base material 23 is formed by resin molding using a resin material having millimeter wave transparency as electromagnetic wave transparency. The resin material used to form the cover base material 23 may be transparent or opaque. In this embodiment, the cover base material 23 is formed from PC (polycarbonate) resin, but may be formed from other resin materials, for example, ABS (acrylonitrile-butadiene-styrene copolymer) resin.

<Heater film 25>
The heater film 25 is for adding a snow-melting function to the millimeter wave transmitting cover 20, and is disposed forward of the cover base material 23. The heater film 25 is shaped to correspond to the shape of the front surface of the cover base material 23. The heater film 25 includes a film base material 26, an adhesive layer 31, a conductive portion 32, and a resist layer 65.

<Film substrate 26>
The film base 26 is a part that forms a framework of the heater film 25. The film base 26 is made of a transparent resin material that is millimeter wave transmissive. In this embodiment, the film base 26 is made of a PET (polyethylene terephthalate) resin.

Figure 3 shows the heater film 25 before the resist layer 65 is formed. As shown in Figures 2 and 3, the film substrate 26 has a main body 27 and a connection portion 29. The main body 27 has a shape corresponding to the cover main body 21 when viewed from the front, that is, an elliptical shape with a larger horizontal dimension than a vertical dimension. The upper portion 28U and lower portion 28L of the edge portion 28 of the main body 27 are located outside the millimeter wave transmission region Z1 and are located at positions facing each other, sandwiching the transmission region Z1 from both sides in the vertical direction.

Here, the radial direction of the elliptical body 27 is referred to as the "inward direction" toward the center O (the intersection of the major and minor axes), and the direction away from the center O is referred to as the "outward direction." Additionally, the direction along the edge 28 of the body 27 is referred to as the "circumferential direction."

As shown in FIG. 10 , the connection portion 29 is a portion to which a device 82 for supplying electric power is connected, and extends radially outward from a portion of the edge portion 28 of the main body portion 27 .
Furthermore, as shown in FIG. 3, of the lower portion 28L, a portion below the center O of the main body portion 27 will be referred to as a "central portion 28C of the lower portion 28L."

In this embodiment, the connection portion 29 extends diagonally downward and leftward in the radial direction from a point shifted leftward from the central portion 28C as a base point.
<Adhesive layer 31>
2, the adhesive layer 31 has a function of adhering the conductive portion 32 to the film substrate 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 substrate 26. As the adhesive layer 31, for example, a transparent film-like optical adhesive sheet called OCA (optical clear adhesive) can be used.

Note that "transparent" in the above-mentioned cover substrate 23, film substrate 26, and adhesive layer 31 includes colorless transparency as well as colored transparency (colored transparency). This also applies to the resin sheet 71 and adhesive layer 72 of the protective section 70 described below.

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

[Pair of terminals]
The pair of terminals includes a positive terminal 33 and a negative terminal 34 that are respectively formed on the rear surface of the connection portion 29 via an adhesive layer 31 .

As shown in Figs. 13 and 14, the positive terminal portion 33 and the negative terminal portion 34 include a plurality of first conductor portions 35 arranged parallel to each other at a distance, and a plurality of second conductor portions 36 arranged parallel to each other at a distance, crossing each first conductor portion 35. In this embodiment, each first conductor portion 35 and each second conductor portion 36 are perpendicular to each other. Two adjacent first conductor portions 35 and two adjacent second conductor portions 36 form a square mesh. The positive terminal portion 33 and the negative terminal portion 34 form a mesh shape in which the mesh is arranged vertically and horizontally. The positive terminal portion 33 and the negative terminal portion 34 are spaced from each other in the circumferential direction of the main body portion 27.

When the connection portion 29, the positive terminal portion 33, and the negative terminal portion 34 are assembled into the millimeter wave transmitting cover 20, they are bent backward along the underside of the edge of the cover base material 23 (not shown).

As shown in FIG. 10, the extending end 33a of the positive terminal portion 33 and the extending end 34a of the negative terminal portion 34 are not covered by a resist layer 65 described later. Connector pins (not shown) are fixed to each of these extending ends 33a, 34a by fixing means such as soldering, adhesive, or crimping. Both extending ends 33a, 34a and both connector pins are arranged together with a part of the connection portion 29 in the film substrate 26 in a socket portion 81 arranged behind the cover substrate 23.

[First electrode portion 40 and second electrode portion 45]
3 and 10, the first electrode portion 40 and the second electrode portion 45 are each formed on the edge portion 28 of the rear surface of the main body portion 27 via an adhesive layer 31. The first electrode portion 40 and the second electrode portion 45 are located outside the millimeter wave transmission region Z1 and are opposed to each other across the transmission region Z1 in the upper and lower directions. The first electrode portion 40 is composed of a first positive electrode portion 41 and a first negative electrode portion 42.

As shown in Figures 5, 7 and 12, the first positive electrode portion 41 extends in the approximately left-right direction along the lower portion 28L. The first positive electrode portion 41 is gently curved so as to bulge downward. The first positive electrode portion 41 has a narrow portion 41a and a wide portion 41b that has a line width greater than that of the narrow portion 41a. The narrow portion 41a extends approximately leftward from the left vicinity of the central portion 28C. The wide portion 41b extends approximately rightward from the left vicinity of the central portion 28C.

As shown in Figures 3 and 10, the first positive electrode portion 41 is connected to the positive terminal portion 33 at the left end of the narrow portion 41a. The right end of the wide portion 41b is located near the right end of the main body portion 27.

As shown in Figures 7, 9, and 10, the first negative electrode portion 42 extends in the approximate 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 Figures 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.

As shown in Figures 7 and 10, in the first negative electrode part 42, the part to the right of the connection part with the negative terminal part 34 is composed of a narrow part 42a with a narrow line width. The right end part of the narrow part 42a is located at a position away to the left of the central part 28C, and is slightly spaced to the left from the wide part 41b. In the first negative electrode part 42, the part to the left of the connection part with the negative terminal part 34 is composed of a wide part 42b with a larger line width than the narrow part 42a.

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 and spaced apart from each other in the radial direction.
On the other hand, as shown in FIG. 3 and FIG. 6, the second electrode portion 45 functions 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 on the upper portion 28U, which is a portion of the edge portion 28 facing the lower portion 28L across the transmission region Z1, via the adhesive layer 31. The second electrode portion 45 extends in the approximately 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 of the second electrode portion 45 is located above the right end of the first positive electrode portion 41. The left end of the second electrode portion 45 is located above the left end of the first negative electrode portion 42.

As described above, the first electrode unit 40 and the second electrode unit 45 face each other in the vertical direction with the transmissive region Z1 in between. Here, the direction along the rear surface of the main body unit 27 in which the first electrode unit 40 and the second electrode unit 45 face each other is referred to as the "facing direction". In addition, the direction that intersects with the facing direction is referred to as the "intersecting direction". The intersecting direction includes a direction perpendicular to the facing direction, as well as a direction that intersects obliquely. In this embodiment, the approximately left-right direction, which is a direction that is approximately perpendicular to the facing direction, corresponds to the intersecting direction.

12 and 13, the first positive electrode portion 41 and the first negative electrode portion 42 each have a plurality of slits 43 extending in the intersecting direction along the lower portion 28L. Each slit 43 extends in the generally left-right direction while gently curving so as to bulge downward. The slits 43 are formed at a plurality of locations on the first positive electrode portion 41 and the first negative 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 spaced apart in the same direction, separated by a connecting portion 44 provided between the slits 43. The slits 43 are also formed at a plurality of locations on the first positive electrode portion 41 and the first negative electrode portion 42 in the radial direction. The plurality of radial slits 43 are spaced apart in the same direction.

Here, the effective line width of the first positive electrode portion 41 is the value obtained by subtracting the width of all slits 43 from the actual line width of the wide portion 41b when it is assumed that the slits 43 are not formed. Similarly, the effective line width of the first negative electrode portion 42 is the value obtained by subtracting the width of all slits 43 from the actual line width of the wide portion 42b when it is assumed that the slits 43 are not formed. The actual line width and effective line width of the first positive electrode portion 41 are larger than the line widths of the heater wire portions 51 and 55 described below. Similarly, the actual line width and effective line width of the first negative electrode portion 42 are larger than the line widths of the heater wire portions 51 and 55.

As shown in FIG. 11, the second electrode portion 45 has a plurality of slits 46 formed therein, which extend in the intersecting direction along the upper portion 28U. Each slit 46 extends in the generally left-right direction while gently curving so as to bulge upward. The slits 46 are formed in a plurality of locations on the second electrode portion 45 in the direction along the upper portion 28U. Adjacent slits 46 in the direction along the upper portion 28U are spaced apart in the same direction, separated by a connecting portion 47 provided between the slits 46. The slits 46 are also formed in a plurality of locations on the second electrode portion 45 in the radial direction. The plurality of radial slits 46 are spaced apart in the same direction.

Here, the effective line width of the second electrode portion 45 is the 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 the slits 46 are not formed. The actual line width and effective line width of the second electrode portion 45 are larger than the line widths of the heater wire portions 51 and 55.

[Multiple heater wire portions 51, 55]
As shown in FIG. 3, the heater wire portions 51, 55 have different shapes in the middle portion and on both sides in the intersecting direction.

As shown in Figures 3 and 7, the heater wire portions 51 located in the intermediate portion are entirely made up of straight line portions 52 that extend linearly in the opposing direction. The straight line portions 52 are formed spaced apart from one another in the intersecting direction. The straight line portions 52 of the heater wire portions 51 located in the center in the intersecting direction are located on or close to the center O.

6 and 7, each heater wire portion 51 has a first end 53 at its lower end and a second end 54 at its upper end. The first end 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 center in the cross direction and the heater wire portion 51 located to the right of that, are connected to the first positive electrode portion 41 at their first ends 53. The remaining heater wire portions 51, in this case the heater wire portion 51 located to the left of the center in the cross direction, are connected to the first negative electrode portion 42 at their first ends 53.

In contrast, the second end 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, which are curved so as to bulge in opposite directions, is widest at the center in the intersecting direction. The distance becomes narrower as the distance from the center in the intersecting direction increases. The length of the heater wire portion 51 is longer at the center in the intersecting direction than in other portions. The length of the heater wire portion 51 becomes shorter as the distance from the center in the intersecting direction increases.

The heater wire portions 55 located on both sides in the intersecting direction, in this embodiment, two heater wire portions 55 on each side, are formed longer than if the entire heater wire portion 55 extended linearly in the opposing direction. 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 opposing direction outside the first electrode portion 40 and the second electrode portion 45 in the intersecting direction. Both ends of each straight portion 56 are located at the lower portion 28L and upper portion 28U of the edge portion 28.

The straight portions 56 of both heater wire portions 55 on each side are shorter than any of the straight portions 52 of the multiple heater wire portions 51. In addition, the length of both straight portions 56 on each side is shorter on the side that is farther from the center in the cross direction.

The first extension portion 57 of each heater wire portion 55 extends from the lower end 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 in correspondence with 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. Adjacent first extension portions 57 on the same side are spaced apart from each other in the radial direction. In addition, of the first extension portions 57, the one connected to the straight portion 56 farthest from the center in the cross direction is longer.

The second extension 61 of each heater wire portion 55 extends from the upper end of the straight portion 56 along the upper portion 28U toward the second electrode portion 45. Each second extension 61 is gently curved so as to bulge upward in correspondence with the upper portion 28U, and has a second end 62. The second end 62 of each second extension 61 is connected to the second electrode portion 45 from the side. Adjacent second extensions 61 on the same side are spaced apart from each other in the radial direction. In addition, of the two second extensions 61, the one connected to the straight portion 56 farthest from the center in the cross direction is longer.

By adding the first extension 57 and the second extension 61 as described above, the total length of the two heater wire sections 55 on each side is made closer to the total length of the heater wire section 51 located in the center in the cross direction.

In this embodiment, the straight line portions 52, 56 of the multiple heater wire portions 51, 55 are formed at regular intervals in the intersecting direction. The interval between adjacent straight line portions 52, 56 is uniform in the intersecting direction. The interval between adjacent straight line portions 52, 56 is preferably 2 mm or more to ensure millimeter wave transparency. However, if the interval is too large, the heat generated by the straight line portions 52, 56 is less likely to be transmitted to the center portion between the adjacent straight line portions 52, 56. Therefore, the interval is set after comprehensively considering the required millimeter wave transparency, uniform heat distribution, resistance value, design, etc. In this embodiment, the interval is set to about 4 mm.

The line width of each of the heater wire portions 51 and 55 is set to about 10 μm.
In addition, in the body portion 27, both end portions in the intersecting direction, or in other words, in the regions outside the heater wire portion 55, no heater wire portion is formed.

<Resist layer 65>
2 and 3, the resist layer 65 is made of an insulating material and covers portions of the conductive portion 32 that are different from the extended end portion 33a of the positive terminal portion 33 and the extended end portion 34a of the negative terminal portion 34, thereby insulating the same portions. Both extended ends 33a, 34a are exposed from the resist layer 65. The above-mentioned connector pin is fixed to this exposed portion in a conductive state.

<About the production of heater film 25>
The heater film 25 having the above structure is manufactured as follows.
The OCA is attached to the rear surface of the film substrate 26 shown in FIG.

The film substrate 26 on which the adhesive layer 31 is formed and the foil made of a conductive material, in this case copper foil, are pressed toward each other by a roller or the like. The foil is attached to the film substrate 26 by the adhesive layer 31.

Next, the foil is patterned. The patterning process is a process in which unnecessary parts of the foil on the adhesive layer 31 are removed using photolithography and an optical mask to form the conductive part 32. This process can also be used to process heater wire parts 51 and 55 with a small line width.

A resist layer 65 is formed by applying a solder resist or the like around the conductive portion 32 in a portion other than the extended ends 33 a and 34 a.
In this manner, the heater film 25 including the film substrate 26, the adhesive layer 31, the conductive portion 32 and the resist layer 65 is produced.

The heater film 25 is bonded to the cover substrate 23, for example, as follows. The heater film 25 is shaped to a shape corresponding to the shape of the front surface of the cover substrate 23. As shown in FIG. 2, a binder layer 67 is attached to the rear surface of the heater film 25. The binder layer 67 is formed from a resin material capable of bonding with the cover substrate 23, such as PMMA (polymethyl methacrylate) resin or the above-mentioned ABS resin.

The heater film 25 with the binder layer 67 attached is placed in a mold as an insert. Molten resin material is filled into the mold behind the binder layer 67, 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, causing the binder layer 67 to exert its adhesive force. The adhesion between the cover base material 23 and the heater film 25 is increased by the binder layer 67.

<Protective part 70>
The protective part 70 includes a resin sheet 71 and an adhesive layer 72, is sheet-shaped, and is disposed forward of the film substrate 26. When the cover body 21 is impacted from the front by a flying stone or the like, the protective part 70 serves to protect the heater film 25, particularly the conductive part 32, from the impact.

The resin sheet 71 is made of a transparent resin material that is permeable to millimeter waves. In this embodiment, the resin sheet 71 is made of PC resin. The resin sheet 71 is shaped to correspond to the shape of the front surface of the film substrate 26.

The adhesive layer 72 is formed of OCA, similar to the adhesive layer 31. The adhesive layer 72 adheres the resin sheet 71 to the front surface of the film substrate 26 in a tight contact state.
The front surface of the resin sheet 71 constitutes the design surface 22 of the millimeter wave transmitting cover 20 .

The millimeter wave transmitting cover 20 has 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.
10, a connector 83 of the device 82 for supplying power is further coupled to the socket portion 81. By this coupling, the positive terminal portion 33 and the negative terminal portion 34 are electrically connected to the device 82 via the connector pins.

Next, the operation of the present embodiment configured as described above will be described, along with the effects that accompany the operation.
2 transmits millimeter waves, which pass through each portion in the transmission region Z1 of the cover body 21. The transmitted millimeter waves are reflected by objects in front of the vehicle, including preceding vehicles, pedestrians, etc., and then pass through the cover body 21 again and are received by the millimeter wave radar device 13. The millimeter wave radar device 13 recognizes objects based on the transmitted and received millimeter waves, and detects the distance, relative speed, etc. between the vehicle 10 and the object.

<Improved millimeter wave transmittance>
(1-1) As shown in Fig. 3, in the multiple heater wire portions 51, 55, the interval between adjacent straight line portions 52, 56 is set to about 4 mm. Therefore, millimeter waves can easily pass between the adjacent straight line portions 52, 56. The straight line portions 52, 56 are unlikely to hinder the transmission of millimeter waves.

(1-2) If the heater wire portions 51, 55 are thick, the millimeter waves are reflected by the heater wire portions 51, 55 and attenuated. In this regard, in this embodiment, the line width of each heater wire portion 51, 55 is set to about 10 μm. Therefore, compared to Patent Document 1, in which the line width of the heater wire portion is 50 μm to 70 μm, the reflection of millimeter waves at the heater wire portions 51, 55 is suppressed, and the millimeter waves are more easily transmitted. In this respect, too, the heater wire portions 51, 55 are less likely to impede the transmission of millimeter waves.

(1-3) The first positive electrode portion 41, the first negative electrode portion 42, and the second electrode portion 45 are located outside the millimeter wave transmission region Z1. Therefore, although the line widths of the first positive electrode portion 41, the first negative electrode portion 42, and the second electrode portion 45 are larger than the line widths of the heater wire portions 51 and 55, they are unlikely to impede the transmission of millimeter waves.

Due to the above (1-1) to (1-3), in this embodiment, the decrease in millimeter wave transmittance caused by the addition of the heater film 25 can be suppressed.
Here, when ice and snow adhere to the design surface 22 of the cover body 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 the present embodiment, power is supplied to the conductive portion 32 from a device 82 shown in Fig. 10.

In the conductive portion 32 shown in FIG. 3, the current flows in the order of the positive terminal portion 33, the first positive electrode portion 41, the heater wire portions 51, 55 that are connected to the first positive electrode portion 41 and located on the right side of the main body portion 27, and the second electrode portion 45. The current also flows in the order of the second electrode portion 45, the heater wire portions 51, 55 that are connected to the first negative electrode portion 42 and located on the left side of the main body portion 27, the first negative electrode portion 42, and the negative terminal portion 34.

Each heater wire portion 51, 55 generates heat when a current flows through it. In FIG. 2, a portion of the heat generated by each heater wire portion 51, 55 is transferred to the design surface 22 via the adhesive layer 31, the film substrate 26, and the protective portion 70. This heat melts the ice and snow adhering to the design surface 22. This suppresses the attenuation of millimeter waves caused by ice and snow, and suppresses a decrease in the detection performance of the millimeter wave radar device 13 caused by the adhesion of ice and snow.

<Improved uniformity of heat distribution>
(2-1) As shown in FIG. 3, the first electrode portion 40 and the second electrode portion 45 are formed at positions behind the edge portion 28 of the main body portion 27 and facing each other in the up-down direction. The right ends of the first electrode portion 40 and the second electrode portion 45 are located near the right end of the main body portion 27. The left ends of the first electrode portion 40 and the second electrode portion 45 are located near the left end of the main body portion 27. Furthermore, each of the multiple 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 portion 53, 58 and to the second electrode portion 45 at the second end portion 54, 62. In this way, the multiple heater wire portions 51, 55 are formed in a wide area of the film substrate 26. Therefore, it is possible to generate heat in a wide area of the heater film 25.

(2-2) In addition, since the multiple heater wire sections 51, 55 are connected in parallel to the first electrode section 40 and the second electrode section 45, the same voltage is applied to each heater wire section 51, 55. Therefore, each heater wire section 51, 55 can generate heat uniformly.

(2-3) Furthermore, since the actual line width and substantial line width of each of the first electrode portion 40 and the second electrode portion 45 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. As a result, 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 cause the heater film 25 to generate heat with a uniform heat distribution by the heater wire portions 51, 55.

(2-4) In this embodiment, the adjacent straight line portions 52, 56 extend in the opposing direction while being parallel to each other and spaced apart in the intersecting direction. The distance between the adjacent straight line portions 52, 56 is uniform in the opposing direction. Therefore, compared to a case in which the distance varies in the opposing direction, heat can be generated between the adjacent straight line portions 52, 56 with a uniform heat distribution in the opposing direction.

(2-5) In this embodiment, the straight line portions 52, 56 are formed at regular intervals in the intersecting direction. Therefore, the intervals between adjacent straight line portions 52, 56 are uniform in the intersecting direction. Therefore, it is easier to cause the heater film 25 to generate heat with a uniform heat distribution in the intersecting direction, compared to when the intervals vary in the intersecting direction.

(2-6) The first electrode portion 40 and the second electrode portion 45 are curved so as to bulge away from each other. Therefore, of the multiple straight line portions 52, 56, the one located at the center in the intersecting direction is the longest. The length of the straight line portions 52, 56 decreases as they move away from the center in the intersecting direction. As the length decreases, the amount of heat generated by the straight line portions 52, 56 decreases. The amount of heat generated is distributed so that the amount of heat generated is large at the center in the intersecting direction and decreases as the distance from the center in the intersecting direction increases.

In this regard, in this embodiment, the heater wire portions 55 located on both sides in the intersecting direction are composed of a straight portion 56, a first extension portion 57, and a second extension portion 61. The heater wire portions 55 on both sides are longer by the amount of the first extension portion 57 and the second extension portion 61 than when they are composed of only the straight portion 56, that is, when the entire heater wire portion 55 extends linearly in the opposing direction.

By lengthening the heater wire portion 55 as described above, the amount of heat generated by the heater wire portion 55 increases, and accordingly, the variation in heat generation distribution in the intersecting direction can be reduced.
In the present embodiment, the entire length of the heater wire portion 55 is close to the longest length located at the center in the intersecting direction, so that the variation in the heat generation distribution can be further reduced.

In particular, as described above, the straight line portion 56 of the heater wire portion 55 becomes shorter the farther it is from the center in the cross direction. However, the first extension portion 57 and the second extension portion 61 of the heater wire portion 55 become longer the farther it is from the center in the cross direction. Therefore, the total length of each heater wire portion 55 can be made close to the length of the longest heater wire portion 51.

(2-7) In the right half of the main body 27, a current can be caused to flow from the first electrode 40 toward the second electrode 45 via the heater wires 51 and 55. In the left half of the main body 27, a current can be caused to flow from the second electrode 45 toward the first electrode 40 via the heater wires 51 and 55.

Therefore, the current can be caused to flow evenly through the entirety of the plurality of heater wire portions 51, 55. The heater film 25 can be caused to generate heat with a more uniform heat distribution.
Incidentally, when visible light is irradiated onto the millimeter wave transmitting cover 20 shown in Fig. 2 from the front of the vehicle 10, the visible light passes through the transparent protective portion 70 and is irradiated onto the heater film 25. The visible light passes through the main body portion 27 of the film substrate 26. The visible light irradiated onto areas where the first electrode portion 40, the second electrode portion 45, and the heater wire portions 51, 55 are not formed is transmitted. The visible light irradiated onto the first electrode portion 40, the second electrode portion 45, and the heater wire portions 51, 55 is reflected.

<Improvement of Appearance of Millimeter Wave Transmitting Cover 20>
(3-1) As described in (2-2) above, the multiple heater wire portions 51, 55 are connected in parallel to the first electrode portion 40 and the second electrode portion 45 (see FIG. 3). This makes it possible to reduce the line width of each heater wire portion 51, 55 compared to the case where the heater wire portions 51, 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, 55, it becomes possible to reduce the line width of each heater wire portion 51, 55.

As the line width of the heater wire portions 51, 55 becomes smaller, the heater wire portions 51, 55 become less visible. This improves the appearance of the heater film 25 and therefore the millimeter wave transmitting cover 20.

(3-2) 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 on the edge portion 28 of the main body portion 27, and therefore are less noticeable than if they were formed radially inward from the edge portion 28. This further improves the appearance of the millimeter wave transmitting cover 20.

(3-3) In this embodiment, as shown in Figs. 11 to 13, slits 43, 46 extending in the intersecting direction along the edge 28 are formed in each of the first electrode portion 40 and the second electrode portion 45. Compared to a case in which the slits 43, 46 are not formed, the first electrode portion 40 and the second electrode portion 45 are less noticeable. Therefore, in this respect as well, the appearance of the millimeter wave transmitting cover 20 is further improved.

(3-4) As shown in FIG. 3, adjacent straight line portions 52, 56 extend in the opposing direction while being spaced apart and parallel to each other in the intersecting direction. The spacing between adjacent straight line portions 52, 56 is uniform in the opposing direction. Therefore, the straight line portions 52, 56 are less visible than when the spacing varies in the opposing direction. Therefore, in this respect as well, the appearance of the millimeter wave transmitting cover 20 is improved.

(3-5) As shown in FIG. 3, multiple straight line portions 52, 56 are formed at regular intervals in the intersecting direction. Therefore, the multiple straight line portions 52, 56 are evenly arranged in the intersecting direction, and the straight line portions 52, 56 are less visible than when the intervals between adjacent straight line portions 52, 56 are different in the intersecting direction. This also improves the appearance of the millimeter wave transmitting cover 20.

(3-6) As shown in FIG. 3, the heater wire portions 55 located on both sides in the intersecting 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 of the straight portion 56 toward the first electrode portion 40. The second extension portion 61 extends from the upper end of the straight portion 56 toward the second electrode portion 45.

Therefore, the first electrode portion 40 becomes shorter with the formation of the first extension portion 57, making the first electrode portion 40 less noticeable, further improving the appearance. In addition, the second electrode portion 45 becomes shorter with the formation of the second extension portion 61, making the second electrode portion 45 less noticeable, further improving the appearance.

In addition to the above, the present embodiment provides the following effects.
(4-1) If the slits 43 were not formed in the first electrode portion 40 and the slits 46 were not formed in the second electrode portion 45, the following phenomenon may occur. That is, there would be a large difference in rigidity between the portions of the heater film 25 where the first electrode portion 40 and the second electrode portion 45 are formed and the portions where they are not formed. The portions of the heater film 25 where the first electrode portion 40 and the second electrode portion 45 are formed would be difficult to bend and deform.

In this embodiment, as shown in Figures 11 to 13, the first electrode portion 40 has a slit 43 extending in the intersecting direction along the lower portion 28L, and the second electrode portion 45 has a slit 46 extending in the intersecting direction along the upper portion 28U.

As a result, the difference in rigidity between the areas of the heater film 25 where the first electrode portion 40 and the second electrode portion 45 are formed and the areas where they are not formed, particularly the areas of the first electrode portion 40 and the second electrode portion 45 and their surrounding areas, becomes smaller.

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

In this case, however, the connecting portion must be formed at a location radially inwardly away from the edge 28 of the cover body 21, which reduces the area capable of generating heat.
3, in this embodiment, 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 extends to the lower portion 28L to be connected to the first electrode portion 40, and also extends to the upper portion 28U to be connected to the second electrode portion 45.

The straight portion 56 of the heater wire portion 55 extends to the lower portion 28L and is connected to the first electrode portion 40 via a first extension portion 57 that extends along the lower portion 28L. The straight portion 56 extends to the upper portion 28U and is connected to the second electrode portion 45 via a second extension portion 61 that extends along the upper portion 28U.

In this way, since the straight portions 52, 56 extend to the lower portion 28L and the upper portion 28U, the area in which heat can be generated is larger than in the case where they are connected in series as described above.
(4-3) As shown in FIGS. 10, 13 and 14, in this embodiment, the plus terminal portion 33 and the minus terminal portion 34 are formed in a mesh shape.

Therefore, the positive terminal portion 33 and the negative terminal portion 34 are likely to bend or deform when subjected to an external force. Therefore, the positive terminal portion 33 and the negative terminal portion 34 can be prevented from cracking or the like when subjected to the above-mentioned force.

The above embodiment can also be implemented as a modified version as follows. The above embodiment and the following modified version can be implemented in combination with each other to the extent that there is no technical contradiction.

<Shape of Cover 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 embodiment, for example, a circular shape, a polygonal shape, or the like.

<Layer structure of heater film 25>
2, the adhesive layer 31 may be formed on the front surface of the film substrate 26, and the conductive portion 32 may be formed on the front surface of the adhesive layer 31. In this case, the film substrate 26 may be made of a non-transparent resin material.

<Regarding the Position of Connection Part 29>
In Figs. 3 and 10, the connection portion 29 may extend from the edge portion 28 of the main body portion 27 at a position different from that in the above embodiment, for example, from the upper portion, side portion, lower portion, etc.

When the connection portion 29 extends downward from the central portion 28C, the first positive electrode portion 41 does not need a narrow portion 41a, and the first negative electrode portion 42 does not need a narrow portion 42a. The first positive electrode portion 41 and the first negative electrode portion 42 are not adjacent to each other in the radial direction, but are adjacent only in the direction along the lower portion 28L (circumferential direction).

<Regarding the First Electrode Unit 40 and the Second Electrode Unit 45>
3, the first electrode unit 40 and the second electrode unit 45 may be arranged to face each other in a direction other than the up-down direction, provided that they are located outside the transmissive region Z1. For example, the first electrode unit 40 and the second electrode unit 45 may be arranged to face each other in the left-right direction, or may be arranged to face each other in a direction along a line that diagonally intersects with a vertical line or a horizontal line.

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

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

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.

A part of the edge 28 of the main body 27 may be formed straight, and a portion of the edge 28 facing the part may be curved so as to bulge away from the 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, and the other is formed in a curved shape that bulges out toward the side away from the one.

<Regarding the heater wire portions 51 and 55>
The straight portions 52, 56 of the heater wire portions 51, 55 may extend in a direction inclined with respect to the opposing direction.

The number of heater wire portions 55 per side may be changed to a number different from that of the above embodiment. The minimum number is 0. This change results in a change in the total number of heater wire portions 51, 55.
When the number of heater wire portions 55 is changed under the condition that the total number of heater wire portions 51 and 55 does not change, the heater wire portion 55 that is the subject of the change is replaced with a heater wire portion 51 .

The length of the heater wire portion 55 may be increased by a method different from that of the above embodiment.
In the modified example indicated by the two-dot chain lines 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 opposing direction while swinging in both directions of the intersecting direction, or in other words, while meandering.

In addition, in the modified example shown by the two-dot chain lines in Figures 8 and 9, the straight line portion 56 of the heater wire portion 55 is changed to a so-called zigzag non-straight line portion 86 that is repeatedly bent in the intersecting direction.

In any of the above modified examples, the non-linear portions 85 and 86 are longer than the linear portion 56 .
When the non-linear portions 85, 86 are provided in the heater wire portion 55 as described above, it is desirable to design the heater wire portion 55 so that the influence on the millimeter wave transmittance and the appearance is minimal.

In addition, when designing the heater wire portion 55 having the non-linear portions 85, 86, it is desirable to design the heater wire portion 55 so that its length approaches the longest of the multiple heater wire portions 51, i.e., the length of the portion located in the center in the crossing direction.

As described above, since the heater wire portion 55 has the non-linear portions 85, 86, when the millimeter wave transmitting cover 20 is in use, if an outward force in the opposing direction is applied from the outside to the cover body portion 21, the following effect can be expected. That is, the non-linear portions 85, 86 are pulled and deformed by the above force. However, the non-linear portions 85, 86 are unlikely to become fully stretched, and the application of excessive tension to the non-linear portions 85, 86 can be suppressed.

In Figs. 8 and 9, at least one of the first extension portion 57 and the second extension portion 61 may be formed in a straight line instead of in an arc shape.
At least one of the first extension portion 57 and the second extension portion 61 may be formed in a meandering or zigzag shape, similar to the non-linear portions 85 and 86 .

Similarly to the non-straight portions 85 and 86 of the heater wire portion 55, the straight portion 52 of the heater wire portion 51 may be changed to a non-straight portion having a meandering or zigzag shape.
In order to achieve a uniform heat distribution, the distance between the straight line portions 52, 56 may be maximum at the center in the intersecting direction and may become smaller as the distance from the center increases.

Furthermore, in a middle portion in the intersecting direction, the interval may be constant in the same direction, and in side portions in the intersecting direction, the interval may be smaller than that in the middle portion.
<Conductive portion 32 as a whole>
The conductive portion 32 may be formed by patterning a metal film of copper, silver, or the like formed by plating, by etching.

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

When the film substrate 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, the portion illustrated in FIG. 2 as the resist layer 65 and the binder layer 67 may be formed by only the binder layer 67.

The binder layer 67 is provided as an adhesive layer that adheres the heater film 25 to the cover substrate 23 when the cover substrate 23 is resin-molded behind the heater film 25. A similar adhesive layer can also be formed by the above-mentioned OCA. In this case, the resist layer 65 and binder layer 67 may be replaced with OCA.

The number of layers in the layer structure that are different from the heater film 25 may be changed to a number different from that in the above embodiment.
- New layers may be added to add functionality.

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

If a layer is added behind the heater film 25, that layer may be either transparent or opaque.
＜Other＞
The millimeter wave transmitting cover 20 may be embodied as an emblem, ornament, mark, or the like of the vehicle 10.

- The electromagnetic wave transparent cover can be applied to any vehicle equipped with a device that transmits and receives electromagnetic waves to detect objects outside the vehicle. In this case, the electromagnetic waves transmitted and received by the device include not only millimeter waves, but also electromagnetic waves such as near-infrared waves.

The device that transmits and receives electromagnetic waves to detect objects outside the vehicle may be a device for rear monitoring, front side monitoring, or rear side monitoring, in addition to forward monitoring. In this case, the electromagnetic wave transparent cover is positioned in front of the device in the direction of electromagnetic wave transmission.

- Electromagnetic wave transparent covers can also be used when devices that transmit and receive electromagnetic waves are installed on vehicles other than cars, such as aircraft, ships, etc.

10...Vehicle (vehicle)
13... Millimeter wave radar device (device)
20...Millimeter wave transparent cover (electromagnetic wave transparent cover)
25...Heater film 32...Conductive portion 33...Positive terminal portion 34...Negative terminal portion 40...First electrode portion 41...First positive electrode portion 42...First negative electrode portion 43, 46...Slit 45...Second electrode portion 51, 55...Heater wire portion 52, 56...Straight portion 53, 58...First end portion 54, 62...Second end portion 57...First extension portion 61...Second extension portion 82...Device Z1...Transmission area

Claims (6)

An electromagnetic wave transparent cover that is applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, is disposed in front of the device in a transmission direction of the electromagnetic waves, has a layered structure in which a plurality of layers are stacked in the transmission direction, and one of the 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 a transmission region of the electromagnetic wave and opposed to each other across the transmission region,
When a direction in which the first electrode portion and the second electrode portion face each other is defined as an opposing direction and a direction intersecting the opposing direction is defined as an 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 and a second end,
the first end of each of the heater wire portions is connected to the first electrode portion, and the second end of each of the heater wire portions is connected to the second electrode portion;
Furthermore, the first electrode portion and the second electrode portion have a line width larger than a line width of the heater wire portion,
The 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 . An electromagnetic wave transparent cover that is applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, is disposed in front of the device in a transmission direction of the electromagnetic waves, has a layered structure in which a plurality of layers are stacked in the transmission direction, and one of the 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 a transmission region of the electromagnetic wave and opposed to each other across the transmission region,
When a direction in which the first electrode portion and the second electrode portion face each other is defined as an opposing direction and a direction intersecting the opposing direction is defined as an 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 and a second end,
the first end of each of the heater wire portions is connected to the first electrode portion, and the second end of each of the heater wire portions is connected to the second electrode portion;
Furthermore, the first electrode portion and the second electrode portion have a line width larger than a line width of the heater wire portion,
Among the plurality of heater wire portions, each of the plurality of heater wire portions located at least in a middle portion in the crossing direction is configured by a straight portion extending linearly in the opposing direction as a whole,
An electromagnetic wave transparent cover, wherein the straight line portions of each of the plurality of heater wire portions located at least in the middle in the intersecting direction extend in the opposing direction while being parallel to and spaced apart from each other in the intersecting direction. The electromagnetic wave transmission cover according to claim 2 , wherein the straight line portions are formed at regular intervals in the intersecting direction in the plurality of heater wire portions located at least in a middle portion in the intersecting direction. one of the first electrode portion and the second electrode portion is curved so as to bulge away from the other, and the other is curved so as to bulge away from the one,
4. The electromagnetic wave transmission cover according to claim 2, wherein among the plurality of heater wire portions, the heater wire portions located on both sides in the intersecting direction are formed longer than when the heater wire portions as a whole extend linearly in the opposing direction. The heater wire portions located on both sides in the cross direction are
a linear portion extending linearly in the opposing direction on an outer side of the first electrode portion and the second electrode portion in the intersecting direction;
a first extension portion extending from one end of the linear portion toward the first electrode portion and having the first end;
5. The electromagnetic wave transparent cover according to claim 4, further comprising a second extension portion extending from the other end of the straight portion toward the second electrode portion and having the second end portion, the first extension portion being connected to the first electrode portion at the first end portion and the second extension portion being connected to the second electrode portion at the second end portion. An electromagnetic wave transparent cover that is applied to a vehicle equipped with a device for transmitting and receiving electromagnetic waves, is disposed in front of the device in a transmission direction of the electromagnetic waves, has a layered structure in which a plurality of layers are stacked in the transmission direction, and one of the 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 a transmission region of the electromagnetic wave and opposed to each other across the transmission region,
When a direction in which the first electrode portion and the second electrode portion face each other is defined as an opposing direction and a direction intersecting the opposing direction is defined as an 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 and a second end,
the first end of each of the heater wire portions is connected to the first electrode portion, and the second end of each of the heater wire portions is connected to the second electrode portion;
Furthermore, the first electrode portion and the second electrode portion have a line width larger than a line width of the heater wire portion,
The conductive portion further includes a positive terminal portion and a negative terminal portion to which a device for supplying power is connected,
the first electrode portion includes a first positive electrode portion connected to the positive terminal portion, and a first negative electrode portion formed in a state spaced apart from the first positive electrode portion and connected to the negative terminal portion,
the first positive electrode portion and the first negative electrode portion are adjacent to each other while being spaced apart from each other at least in the intersecting direction,
the second electrode portion faces the first positive electrode portion and the first negative electrode portion as a relay electrode portion between the first positive electrode portion and the first negative electrode portion,
an electromagnetic wave transparent cover, the first ends of some of the heater wire portions being connected to the first positive electrode portion, the second ends of the some of the heater wire portions being connected to the second electrode portion, the first ends of the remaining heater wire portions being connected to the first negative electrode portion, and the second ends of the remaining heater wire portions being connected to the second electrode portion.

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