Patent Publication Number: US-2022234519-A1

Title: Vehicle exterior component

Description:
BACKGROUND 
     1. Field 
     The present disclosure relates to a vehicle exterior component that decorates a vehicle, such as an emblem, an ornament, or a mark. 
     2. Description of Related Art 
     A millimeter wave radar device installed in a vehicle transmits millimeter waves to the outside of the vehicle. The millimeter waves that hit, and are reflected by, an object outside the vehicle, such as a leading vehicle or a pedestrian, are received by the millimeter wave radar device. Based on the transmitted and received millimeter waves, the millimeter wave radar device recognizes the object and detects the distance and the relative velocity between the vehicle and the object. 
     The above-described vehicle includes a vehicle exterior component, such as an emblem, that is located forward of the millimeter wave radar device in the transmission direction of millimeter waves. The vehicle exterior component includes a decorative main body. The decorative main body conceals the millimeter wave radar device and is transmissive to millimeter waves. 
     When snow and ice collect on the ornamental surface (the front surface) of the vehicle exterior component, millimeter waves are attenuated, which reduces the detection performance of the millimeter wave radar device. In this regard, vehicle exterior components equipped with a snow melting function have been developed. For example, a heater sheet may be stacked on the front side of the decorative main body to provide a snow melting function. 
     The heater sheet includes a heating wire and a sheet base. The heating wire is configured to generate heat when energized. The heating wire is routed on the back surface of the sheet base. The heater sheet includes a heating main body and an extending portion. The heating main body is closer to the front side than the decorative main body. The extending portion extends from the periphery of the heating main body and is bent along the outer circumference of the decorative main body to be arranged at a position closer to the back side than the front surface of the decorative main body. 
     In the above-described vehicle exterior component, the heating wire generates heat when energized. Thus, when ice and snow collect on the ornamental surface (the front surface) of the vehicle exterior component, the heat generated by the heating wire melts the ice and snow, reducing attenuation of millimeter waves caused by collected ice and snow. 
     A typical example of a vehicle exterior component may include a technique for stacking a heater sheet on the front side of a decorative main body. 
     In the above-described typical vehicle exterior component, the extending portion of the heater sheet is stretched when being bent along the outer circumference of the decorative main body. Once the vehicle exterior component is installed in a vehicle, repeated changes in the ambient temperature may occur. When a section of the extending portion that has been stretched due to the bending action is expanded or contracted due to temperature changes, the heating wire may fail to adapt to expansions and contractions of the sheet base, and break. 
     Such a problem can occur not only in millimeter wave radar devices, but also in any type of vehicle exterior component that is installed in a vehicle equipped with a device that transmits and receives electromagnetic waves to detect an outside object, and includes a heater sheet on the front side of a decorative main body. Also, a phenomenon similar to the one described above can occur in a vehicle exterior component that is installed in a vehicle without a device that transmits and receives electromagnetic waves, but still includes a heater sheet on the front side of a decorative main body. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     In one aspect, a vehicle exterior component is provided that includes a decorative main body configured to decorate a vehicle, and a heater sheet that includes a heating wire and a sheet base made of a plastic. The heating wire is configured to generate heat when energized and is routed on a back surface of the sheet base. The heater sheet includes a heating main body and an extending portion. The heating main body is arranged to be closer to a front side than the decorative main body. The extending portion extends from a periphery of the heating main body and is bent along an outer circumference of the decorative main body to be arranged at a position closer to a back side than a front surface of the decorative main body. The extending portion includes a bent portion that is bent along the outer circumference. A wire length of the heating wire in the bent portion is set to a length that allows the heating wire to change a shape to adapt to expansions and contractions of the sheet base in the bent portion caused by changes in an ambient temperature. 
     In another aspect, a vehicle exterior component is provided that includes a decorative main body configured to decorate a vehicle, and a heater sheet that includes a heating wire and a sheet base made of a plastic. The heating wire is configured to generate heat when energized and is routed on a back surface of the sheet base. The heater sheet includes a heating main body and an extending portion. The heating main body is arranged to be closer to a front side than the decorative main body. The extending portion extends from a periphery of the heating main body and is bent along an outer circumference of the decorative main body to be arranged at a position closer to a back side than a front surface of the decorative main body. The extending portion includes a bent portion that is bent along the outer circumference. A direction in which the extending portion extends from the heating main body is referred to as an extending direction. An amount of change in the ambient temperature is represented by a temperature change amount ΔT. A difference between a linear thermal expansion coefficient of the sheet base and a linear thermal expansion coefficient of the heating wire is represented by a linear thermal expansion coefficient difference ΔA. A length of the bent portion in the extending direction is represented by an extending length Le. A wire length of the heating wire in the bent portion is represented by a wire length Lh. The wire length Lh satisfies a following Expression 1 
         Lh≤Le+ΔT×ΔA×Le    (Expression 1).
 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an emblem, which is a vehicle exterior component according to one embodiment. 
         FIG. 2  is a partial rear view illustrating a heater sheet according to the embodiment of  FIG. 1 . 
         FIG. 3  is a partial cross-sectional side view illustrating a lower structure of the emblem according to the embodiment of  FIG. 1 , together with part of a front grille and part of a millimeter wave radar device. 
         FIG. 4  is a cross-sectional view of a socket portion, taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a partial developed view of an extending portion of the heater sheet according to the embodiment of  FIG. 1 . 
     
    
    
     Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted. 
     Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art. 
     In this specification, “at least one of A and B” should be understood to mean “only A, only B, or both A and B.” 
     A vehicle exterior component according to one embodiment will now be described with reference to the drawings. In the present embodiment, the vehicle exterior component is an emblem attached to a front portion of a vehicle. 
     In the following description, the direction in which the vehicle advances forward will be referred to as the front, and the reverse direction will be referred to as the rear. The vertical direction refers to the vertical direction of the vehicle, and the left-right direction refers to the vehicle width direction that agrees with the left-right direction when the vehicle is advancing forward. In the drawings, in order to make the size of each component recognizable, the scale of each component is altered as necessary. 
     As shown in  FIG. 3 , a vehicle  10  is equipped with a front monitoring millimeter wave radar device  13  arranged at the front. The millimeter wave radar device  13  is located at the center in the left-right direction and behind a front grille  11 . The millimeter wave radar device  13  transmits millimeter waves, which are included in electromagnetic waves, to the outside of the vehicle  10 , specifically, toward the front, and receiving the millimeter waves that have struck and been reflected by an object outside the vehicle  10 . Millimeter waves are radio waves with wavelengths of 1 mm to 10 mm and frequencies of 30 GHz to 300 GHz. 
     Like a typical front grille, the front grille  11  has an uneven thickness. The front grille  11  may include a plastic base with plating on the surface. The front grille  11  thus interferes with the transmitted or reflected millimeter waves. As such, the front grille  11  has a window  12 , which is located in front of the millimeter wave radar device  13  in the transmission direction of the millimeter waves.  FIG. 3  shows a lower part of the window  12 . 
     An emblem  15  is disposed in the window  12 . The surface of the emblem  15  in the forward direction of the vehicle  10  (the surface on the right side as viewed in  FIG. 3 ) includes an ornamental surface  15   a.  The outer shape of the ornamental surface  15   a  is horizontally oval (refer to  FIG. 1 ). In the following description of the emblem  15 , the side at which the ornamental surface  15   a  is disposed will be referred to as a front side, and the side opposite to the ornamental surface  15   a  (the left side as viewed in  FIG. 3 ) will be referred to as a back side. 
     The emblem  15  is arranged in an upright state. In this arranged state, the front side in the emblem  15  corresponds to the front side of the vehicle  10 , and the back side of the emblem  15  corresponds to the rear side in the vehicle  10 . 
     Thus, in order to define directions corresponding to the front-rear direction of the vehicle  10 , the words “front” and “back” will be used when the emblem  15  is described. The same applies to a case in which the emblem  15  attached to the vehicle  10  is described. 
     The emblem  15  includes a decorative main body  21  and a heater sheet  51 . The components constituting the emblem  15  will now be described. 
     &lt;Decorative Main Body  21 &gt; 
     As shown in  FIGS. 1 and 3 , the decorative main body  21  is arranged on the front side in the transmission direction of millimeter waves from the millimeter wave radar device  13  in the vehicle  10  to decorate the vehicle  10 . The main portion of the decorative main body  21  is a plate having a horizontally oval shape in correspondence with the ornamental surface  15   a  of the emblem  15 . Also, the main portion of the decorative main body  21  is transmissive to millimeter waves. 
     The decorative main body  21  includes a base  22 , a transparent plastic layer  35 , and a decorative layer  41 . The base  22  is a component that constitutes the back-side portion of the decorative main body  21 . The base  22  includes a base main body  23 , which forms the framework, and a frame  31 , which is provided in the outer circumference of the base main body  23 . 
     The base main body  23  is made of a colored plastic of acrylonitrile-ethylene-styrene (AES) copolymer. The base main body  23  includes a general portion  24  and a protrusion  25  on the front side. The general portion  24  is nearly orthogonal to the front-rear direction and substantially flat. The protrusion  25  protrudes forward from the general portion  24 . The general portion  24  corresponds to a background area  16  of the emblem  15  as viewed in  FIG. 1 . The protrusion  25  corresponds to a pattern area  17  of the emblem  15 . In the present embodiment, the pattern area  17  is formed by a letter  18 , which is “A” and an annular portion  19  surrounding the letter  18 . 
     As shown in  FIG. 3 , the base main body  23  includes an annular recess  26  in the outer circumference. The annular recess  26  is open in the surface on the front side of the base main body  23  and is recessed toward the back side. The annular recess  26  has an annular oval shape corresponding to the periphery of the base main body  23 . 
     The base  22  includes a socket  27  in a lower portion. The socket  27  protrudes backward. The socket  27  is configured to receive a plug B of a device A for supplying power. The socket  27  includes a recess  28  in the front side. The recess  28  extends toward the back from the annular recess  26 . Further, the socket  27  includes a recess  29 , which is open in the back surface of the socket  27  and is recessed toward the front side. 
     In place of AES plastic, the base main body  23  may be made of, for example, acrylonitrile-styrene-acrylate (ASA) plastic, polycarbonate (PC) plastic, and a polymer alloy of PC plastic and acrylonitrile-butadiene-styrene (ABS) copolymer. 
     The frame  31  is provided along the outer circumference of the base main body  23  so as to have an annular oval shape (refer to  FIG. 1 ). Most of the frame  31  is formed to fill the annular recess  26 . Part of the lower portion of the frame  31  is formed to fill the recess  28  of the socket  27 . The frame  31  is made of black plastic that is a mixture of PC plastic and carbon black. 
     As shown in  FIGS. 3 and 4 , two connector pins  32 , which extend in the front-rear direction, are provided in the socket  27 . The connector pins  32  are spaced apart from each other in the left-right direction. Each connector pin  32  includes a front-side portion  32   a,  which has a shape of a flat plate. The front-side portions  32   a  are embedded in the base main body  23  and the frame  31 . Also, each connector pin  32  includes a rod-shaped back-side portion  32   b.  The back-side portions  32   b  are partially arranged in the recess  29 . 
     The base  22  includes a window  30  in an outer circumference  22   a.  The window  30  is located in the lower portion of the socket  27  and opens in the lower surface of the socket  27 . The window  30  is provided to allow the heating wires  56 ,  57 , which will be discussed below, to be joined to the connector pins  32 . 
     The base  22  (the base main body  23 ) includes attachment portions (not shown) at several positions along the periphery of the back surface. The attachment portions are used to attach the emblem  15  to the front grille  11  or the vehicle body. The attachment portions include, for example, clips, screws, or engaging hooks. 
     As shown in  FIGS. 1 and 3 , the transparent plastic layer  35  is the front-side portion of the main part of the decorative main body  21 . The transparent plastic layer  35  is made of a transparent PC plastic. The term “transparent” as used in this description includes not only “colorless transparent,” but also “colored transparent.” The same applies to a sheet base  55 , which will be discussed below. The back-side portion of the transparent plastic layer  35  has a shape that corresponds to the shape of the front-side portion of the base main body  23 . That is, the transparent plastic layer  35  includes a general portion  36  on the back-side portion, which corresponds to the front side of the general portion  24  of the base main body  23 . The general portion  36  is nearly orthogonal to the front-rear direction and substantially flat. The transparent plastic layer  35  includes a recess  37  on the back-side portion, which corresponds to the front side of the protrusion  25  of the base main body  23 . The recess  37  is recessed toward the front side with respect to the general portion  36 . The outer circumference of the transparent plastic layer  35  is located on the front side of the frame  31 . In place of PC plastic, the transparent plastic layer  35  may be made of a transparent plastic, such as polymethyl methacrylate (PMMA). 
     The decorative layer  41  is provided in an area between the base main body  23  and the transparent plastic layer  35  surrounded by the frame  31 . Also, the decorative layer  41  is transmissive to millimeter waves. The decorative layer  41  is composed by combining a colored decorative layer, which has a deep color such as black or blue, and a luster decorative layer, which is made of metal such as indium (In). 
     In the decorative main body  21 , the frame  31  is welded to the base main body  23  and the transparent plastic layer  35 , so as to connect the base main body  23  and the transparent plastic layer  35  to each other. 
     The area in the decorative main body  21  through which millimeter waves pass has a uniform thickness. 
     &lt;Heater Sheet  51 &gt; 
     As shown in  FIGS. 2 and 3 , the heater sheet  51  includes the sheet base  55  and the two heating wires  56 ,  57 . The sheet base  55  is made of a transparent plastic such as PC plastic. The heating wires  56 ,  57  are made of a metal that generates heat when energized, and are routed on the back surface of the sheet base  55 . 
     The heater sheet  51  includes a heating main body  52  and an extending portion  53 . The extending portion  53  extends from the periphery of the heating main body  52 , specifically, from the lower edge of the heating main body  52  in the present embodiment. The direction in which the extending portion  53  extends from the heating main body  52  is referred to as an extending direction of the extending portion  53 . A direction along the surface of the extending portion  53  and orthogonal to the extending direction is referred to as a width direction of the extending portion  53 . The heating main body  52  has a shape of a horizontally oval plate in correspondence with the ornamental surface  15   a  of the emblem  15 . The heating main body  52  is stacked on the front side of the transparent plastic layer  35  of the decorative main body  21 . In the heating main body  52 , the heating wires  56 ,  57  are routed in different patterns (refer to  FIG. 2 ). 
     As shown in  FIG. 3 , the extending portion  53  is bent along the lower surface of the transparent plastic layer  35  and the lower surface of the frame  31 , so as to be put around the lower end of the outer circumference of the decorative main body  21  and reach the back side of a front surface  21   a  of the decorative main body  21 . In order to distinguish sections in the extending portion  53 , the section that is bent in the above-described manner is referred to as a bent portion  53   b  as shown in  FIG. 5 . The bent portion  53   b  is an area extending in the extending direction between the broken line in  FIG. 5  and openings  54 , which will be discussed below. A section in the extending portion  53  between the heating main body  52  and the bent portion  53   b  is referred to as an extending front portion  53   a.  A section in the extending portion  53  on a side of the bent portion  53   b  opposite to the extending front portion  53   a,  in other words, a section closer to the back side than the bent portion  53   b,  is referred to as an extending back portion  53   c.    
     The bent portion  53   b  has a stadium-shaped insertion hole  55   a,  which extends in the extending direction, in the center in the width direction. Also, although not illustrated, the decorative main body  21  has an attachment boss at a position that corresponds to the insertion hole  55   a.  When the heater sheet  51  is attached to the decorative main body  21 , the attachment boss is inserted into the insertion hole  55   a,  so that the extending portion  53  and thus the heater sheet  51  are positioned in relation to the decorative main body  21 . 
     The extending back portion  53   c  has the openings  54  in the sides in the width direction. The openings  54  are spaced apart from each other in the width direction. In the present embodiment, the openings  54  are rectangular. However, the openings  54  may have another shape. 
     As shown in  FIGS. 2, 4, and 5 , the two heating wires  56 ,  57  are routed not only in the heating main body  52 , but also in the extending portion  53 . That is, the heating wire  56  has terminals  56   a,    56   b  at the opposite ends. The heating wire  57  has terminals  57   a,    57   b  at the opposite ends. The terminals  56   a,    57   a  are arranged on the back surface of the extending portion  53  and closely arranged at one side in the width direction. The terminals  56   a,    57   a  have the same polarity. The terminals  56   b,    57   b  are arranged on the back surface of the extending portion  53  and closely arranged at the other side in the width direction. The terminals  56   b,    57   b  have the same polarity that is different from the polarity of the terminals  56   a,    57   a.    
     As shown in  FIG. 5 , the terminals  56   a,    57   a  and the terminals  56   b,    57   b  are routed in the same manner (in an axisymmetrical manner). Therefore, in the following description, only the terminals  56   a,    57   a  will be described, and the illustration of the terminals  56   b,    57   b  will be omitted. 
     The terminals  56   a,    57   a  are routed in different patterns between the extending back portion  53   c  and the region including the extending front portion  53   a  and the bent portion  53   b.  The terminals  56   a,    57   a  are routed to extend linearly in the extending direction in the extending back portion  53   c.  Parts of the terminals  56   a,    57   a  cross the openings  54  in the extending direction. 
     The sections of the terminals  56   a,    57   a  in the bent portion  53   b  are set to have lengths that allow the terminals  56   a,    57   a  to change their shapes to adapt to expansions and contractions of the sheet base  55  in the bent portion  53   b  caused by changes in the ambient temperature. 
     The amount of change in the ambient temperature is represented by a temperature change amount ΔT. The difference between the linear thermal expansion coefficient of the sheet base  55  and the linear thermal expansion coefficient of the heating wires  56 ,  57  is represented by a linear thermal expansion coefficient difference ΔA. The length of the bent portion  53   b  in the extending direction is represented by an extending length Le. The length of the sections of the terminals  56   a,    57   a  in the bent portion  53   b  is represented by a wire length Lh. 
     The wire length Lh is set to satisfy the following Expression 1. 
         Lh≥Le+ΔT×ΔA×Le    (Expression 1)
 
     Specifically, the terminals  56   a,    57   a  are routed in wavy patterns that advance in the extending direction while oscillating to opposite sides in the width direction in the region including the bent portion  53   b  and the extending front portion  53   a.  The bent portion  53   b  has the insertion hole  55   a  as described above. With respect to the extending direction, the section of the bent portion  53   b  that includes the insertion hole  55   a  has a net dimension in the width direction that is smaller than the dimension of the extending front portion  53   a.  Accordingly, the terminals  56   a,    57   a  have oscillating pattern in the width direction with a smaller amplitude in the bent portion  53   b  than in the extending front portion  53   a.    
     In the present embodiment, the wire length Lh is set to a value greater than or equal to 1.04 times the extending length Le. This setting allows the terminals  56   a,    57   a  to change shape to adapt to expansions and contractions of the sheet base  55  in the bent portion  53   b  caused by changes in the ambient temperature, even if variations in the shape and size of the emblem  15  are maximal in possible ranges. 
     Further, sections of the terminals  56   a,    57   a  that are located at the boundary between the extending portion  53  (the extending front portion  53   a ) and the heating main body  52  are located on the front side of the frame  31 . 
     As shown in  FIGS. 3 and 4 , a section of the extending portion  53  that reaches the back side via the lower end of the outer circumference of the decorative main body  21  is arranged between the frame  31  and the inner wall surface of the recess  28 . 
     A section of the extending portion  53  that surrounds the openings  54  is stacked on part of the front-side portion  32   a  of each connector pin  32  from the front side (the outer circumference). The terminals  56   a,    57   a  are joined to the front-side portion  32   a  of one of the connector pins  32  by performing welding in one of the openings  54 . Likewise, the terminals  56   b,    57   b  are joined to the front-side portion  32   a  of the other connector pin  32  by performing welding in the other opening  54 . In  FIGS. 3 and 4 , the reference numerals  58  denote joint portions that are made of a solder alloy and formed by soldering. The joint portions  58  electrically connect the terminals  56   a,    56   b  and the terminals  57   a,    57   b  to the front-side portions  32   a  of the connector pins  32  in the outer circumference  22   a  of the base  22 . 
     The above-described joining does not necessarily need to be performed by soldering, but may be performed by welding, crimping, or adhesion using an electrically conductive adhesive. 
     The sections at which the terminals  56   a,    56   b  and the terminals  57   a,    57   b  are joined to the connector pins  32  by the joint portions  58  are referred to as joint sections. A water stop portion  71 , which restricts entry of water into the joint sections, is provided in the window  30 . The water stop portion  71  is formed by filling the window  30  with plastic. 
     The emblem  15 , which has the above-described configuration, is disposed in the window  12  while being set vertical as shown in  FIG. 3  and attached to the front grille  11  or the vehicle body at the attachment portions. 
     Further, the plug B of the device A is inserted into the recess  29  of the socket  27  from the back side of the emblem  15 , so that the heating wires  56 ,  57  are electrically connected to the device A. 
     Operation of the above-described embodiment will now be described. Advantages that accompany the operation will also be described. 
     At the time of manufacture of the emblem  15  according to the present embodiment, the bent portion  53   b  of the extending portion  53  of the heater sheet  51  is bent along the outer circumference of the decorative main body  21  as shown in  FIGS. 3 and 5 . At this time, the bent portion  53   b  is stretched in the extending direction of the extending portion  53 . 
     Therefore, after the emblem  15 , which has been manufactured with the bent portion  53   b  in a stretched state as described above, is attached to the vehicle  10 , repeated changes in the ambient temperature expand and contract the bent portion  53   b  of the extending portion  53 , which was stretched through the bending operation. 
     If the terminals  56   a,    56   b  of the heating wire  56  and the terminals  57   a,    57   b  of the heating wire  57  extend linearly in the extending direction in the bent portion  53   b,  the following drawbacks may be caused. That is, if the bent portion  53   b  is expanded or contracted through changes in the temperature, the terminals  56   a,    56   b  and the terminals  57   a,    57   b  may fail to adapt to expansion and contraction of the sheet base  55 . In this case, the terminals  56   a,    56   b  and the terminals  57   a,    57   b  in a maximally stretched state may be broken by being pulled excessively. 
     In this regard, in the present embodiment, as shown in  FIG. 5 , the terminals  56   a,    56   b  and the terminals  57   a,    57   b  are routed in wavy patterns that advance in the extending direction while oscillating in the width direction of the extending portion  53  in the bent portion  53   b  of the extending portion  53 . This routing allows the wire length Lh to satisfy the relationship represented by the Expression 1. This setting allows the terminals  56   a,    56   b  and the terminals  57   a,    57   b  to have lengths that allow for changes in shape so as to adapt to expansions and contractions of the sheet base  55  in the bent portion  53   b  caused by changes in the ambient temperature. 
     Since the heating wires  56 ,  57  change shape to adapt to expansions and contractions of the sheet base  55  in the bent portion  53   b,  the terminals  56   a,    56   b  and the terminals  57   a,    57   b  are allowed to expand and contract in the extending direction. Thus, in the present embodiment, repeated changes in the ambient temperature will not maximally stretch the terminals  56   a,    56   b  and the terminals  57   a,    57   b  in the extending direction. Also, the terminals  56   a,    56   b  and the terminals  57   a,    57   b  in a maximally stretched state will not be pulled excessively in the extending direction. This prevents the terminals  56   a,    56   b  and the terminals  57   a,    57   b  from being broken in the bent portion  53   b.    
     When ice and snow collect on the ornamental surface  15   a  of the emblem  15 , power is supplied to the heating wires  56 ,  57  via the plug B of the device A and the connector pins  32  as shown in  FIGS. 2 and 3 . The heating wires  56 ,  57  are thus energized to generate heat. Some of the heat generated by the heating wires  56 ,  57  is transferred to the ornamental surface  15   a  of the emblem  15 . The transferred heat melts the ice and snow collected on the ornamental surface  15   a,  thereby reducing the attenuation of millimeter waves caused by ice and snow. 
     Particularly, the heater sheet  51  is located in the forefront section in the emblem  15  in the present embodiment. This allows the heat generated by the heating wires  56 ,  57  to be readily transferred to the ornamental surface  15   a  (the front surface) of the emblem  15 , so that ice and snow are melt efficiently. 
     Millimeter waves transmitted by the millimeter wave radar device  13  pass through, in the order, the base main body  23 , the decorative layer  41 , and the transparent plastic layer  35  in the decorative main body  21  of the emblem  15 , and the heating main body  52  of the heater sheet  51 . After passing through these components, the millimeter waves hit and are reflected by an object in front of the vehicle, such as a leading vehicle or a pedestrian, and then pass through, in the order, the heating main body  52  of the heater sheet  51 , and the transparent plastic layer  35 , the decorative layer  41 , and the base main body  23  in the decorative main body  21 . After passing through the decorative main body  21 , the millimeter waves are received by the millimeter wave radar device  13 . Based on the transmitted and received millimeter waves, the millimeter wave radar device  13  recognizes the object and detects the distance and the relative velocity between the vehicle  10  and the object. 
     When the emblem  15  is irradiated with visible light from ahead of the vehicle  10 , the visible light passes through the heating main body  52  of the heater sheet  51  and the transparent plastic layer  35  of the decorative main body  21 , and is reflected by the decorative layer  41 . When the emblem  15  is seen from ahead of the vehicle  10 , the decorative layer  41  appears to be located behind (farther than) the heating main body  52  and the transparent plastic layer  35 . The decorative layer  41  thus decorates the emblem  15 , improving the appearance of the emblem  15  and the surrounding portion. 
     The reflection of visible light on the decorative layer  41  occurs at a position forward of the millimeter wave radar device  13 . The decorative layer  41  conceals the millimeter wave radar device  13 . Accordingly, the millimeter wave radar device  13  cannot be seen easily from ahead of the emblem  15 . The appearance is thus improved as compared with a case in which the millimeter wave radar device  13  can be seen through the emblem  15 . 
     In addition to the ones listed above, the present embodiment has the following advantages. 
     In the present embodiment, as shown in  FIGS. 3 and 4 , one of the connector pins  32  and the terminals  56   a,    57   a  are joined to each other in the outer circumference  22   a  of the base  22 . Also, the other connector pin  32  and the terminals  56   b,    57   b  are joined to each other in the outer circumference  22   a.  The joint sections are covered with the outer circumference  22   a.  The joint sections thus do not degrade the appearance as compared to a case in which joining is performed on the front side of the transparent plastic layer  35 . 
     In the present embodiment, the terminals  56   a,    56   b  and the terminals  57   a,    57   b  are routed in wavy patterns in the extending front portion  53   a  as shown in  FIG. 5 . Thus, as in the case of the bent portion  53   b,  since the heating wires  56 ,  57  change shape to adapt to expansions and contractions of the sheet base  55  in the extending front portion  53   a,  the terminals  56   a,    56   b  and the terminals  57   a,    57   b  are allowed to expand and contract in the extending direction. This further effectively prevents the terminals  56   a,    56   b  and the terminals  57   a,    57   b  from being broken, even if the ambient temperature changes repeatedly. 
     The terminals  56   a,    56   b  and the terminals  57   a,    57   b  are routed in wavy patterns in the boundary between the extending front portion  53   a  and the heating main body  52 , and the wavy sections are located on the front side of the black frame  31 . Accordingly, the wavy sections cannot be seen easily from the outside of the vehicle  10 . 
     Further, the bent portion  53   b  is closer to the back side than the transparent plastic layer  35  as shown in  FIG. 3 . Thus, although the terminals  56   a,    56   b  and the terminals  57   a,    57   b  are routed in wavy patterns in the bent portion  53   b,  these wavy sections cannot be seen easily from the outside of the vehicle  10 . 
     Therefore, the appearance is prevented from being degraded by sections of the heating wires  56 ,  57  in which wavy patterns are visible from the outside of the vehicle  10 . 
     The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other. 
     The number of the heating wires  56 ,  57  in the heater sheet  51  may be changed to one or a number greater than two. 
     The extending portion  53  may extend from a position different from the lower edge of the periphery of the heating main body  52 , for example, from the upper edge or a side end. 
     The outer shape of the ornamental surface  15   a  of the emblem  15  may be changed to a shape that is different from a horizontally oval shape. 
     The terminals  56   a,    56   b  and the terminals  57   a,    57   b  in the bent portion  53   b  may be routed in a pattern different from that in the above-described embodiment, for example, in a zigzag pattern. The same modification may be applied to the extending front portion  53   a.    
     The terminals  56   a,    56   b  and the terminals  57   a,    57   b  in the extending front portion  53   a  may be routed to extend linearly in the extending direction. 
     The above-described embodiment may be applied to any vehicle exterior component that is installed in a vehicle equipped with a device that transmits and receives electromagnetic waves to detect an outside object, and includes a heater sheet on the front side of a decorative main body. In this case, the electromagnetic waves transmitted and received by the device include millimeter waves and infrared rays. 
     The device that transmits and receives electromagnetic waves to detect an outside object is not limited to a front monitoring device, but may be a device that monitors the situation behind the vehicle, the situation on the sides of the front part of the vehicle, or the situation on the sides of the rear part of the vehicle. In these cases, the vehicle exterior component is located forward of the device in the transmission direction of millimeter waves. 
     The above-described vehicle exterior component may be installed in a vehicle that is not equipped with a device that transmits and receives electromagnetic waves to detect an outside object. 
     In addition to an emblem, the above-described embodiment may be applied to a vehicle exterior component that decorates a vehicle, such as an ornament and a mark. 
     Various changes in form and details may be made to the examples above without departing from the spirit and scope of the claims and their equivalents. The examples are for the sake of description only, and not for purposes of limitation. Descriptions of features in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if sequences are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined differently, and/or replaced or supplemented by other components or their equivalents. The scope of the disclosure is not defined by the detailed description, but by the claims and their equivalents. All variations within the scope of the claims and their equivalents are included in the disclosure.