Patent Publication Number: US-11640868-B2

Title: Laminated coil component

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application from U.S. patent application Ser. No. 16/141,056, filed on Sep. 25, 2018, based on and claims the benefit of priority from Japanese Patent Application Serial No. 2017-190553 (filed on Sep. 29, 2017), the contents of which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a laminated coil component used in an electronic circuit. More specifically, the present invention relates to an improvement in inductance in a laminated coil component. 
     BACKGROUND 
     There is conventionally known a laminated coil component provided with a laminate including a plurality of insulating layers stacked together and a coil conductor embedded in the laminate. One example of such a laminated coil component is a laminated inductor. The laminated inductor is a passive element used in an electric circuit. For example, the laminated inductor is used to eliminate noise in a power source line or a signal line. 
     The laminate of the laminated coil component is fabricated by stacking a plurality of green sheets together and firing the thus stacked green sheets. The green sheets are made of a magnetic material such as ferrite. The plurality of green sheets each have a corresponding conductor pattern formed thereon before they are stacked together. The coil conductor is formed by stacking together green sheets each having a conductor pattern formed thereon and electrically connecting, by way of a via, the conductor pattern formed on each of the green sheets to another one of the green sheets. 
     There has been a demand that such a laminated coil component be reduced in size. When reduced in size, the laminated coil component is likely to have a reduced core area. A size reduction of the laminated coil component, therefore, might lead to a decrease in inductance. 
     In a case where the laminated coil component is used in a high-frequency circuit, there is also a demand for an improvement in frequency characteristics. Frequency characteristics of the laminated coil component can be improved by decreasing a stray capacitance between the coil conductor and an external conductor. 
     Japanese Patent Application Publication No. Hei 10-199729 (“the &#39;729 Publication”) discloses a laminated coil component for achieving a high inductance and excellent frequency characteristics. In the laminated coil component of the &#39;729 Publication, a coil conductor is formed so that a coil axis is inclined with respect to a lamination direction of a laminate. According to the laminated coil component, a stray capacitance between an external electrode and the coil conductor can be decreased. Such a decrease in stray capacitance can be achieved without requiring a size reduction of the coil conductor, and thus according to the laminated coil component of the &#39;729 Publication, it is also possible to prevent a decrease in inductance resulting from a reduction in core area. 
     It is demanded that an inductance in the laminated coil component be further improved. In the coil conductor of the laminated coil component of the above &#39;729 Publication, since the coil axis is inclined with respect to the lamination direction of the laminate, a magnetic flux excited by the laminated coil component has to pass through a core of the laminated coil component along the inclined coil axis. Consequently, in the laminated coil component of the &#39;729 Publication, compared with a coil conductor formed so that a coil axis is parallel to a lamination direction of a laminate, a length of a path through which an excited magnetic flux passes (a magnetic path length) is increased. In the laminated coil component, such an increase in magnetic path length might lead to a degradation in inductance. 
     In order to obtain a high magnetic permeability, as an insulating material for each of the insulating layers of the laminate, a composite resin material including metal particles of a soft magnetic material has been used in place of ferrite. Such an insulating layer made of a composite resin material including metal particles has an insulation property lower than that of ferrite, and thus there is a fear that insulation between the coil conductor and an external electrode might not be ensured. It is, therefore, desired that insulation reliability between the coil conductor and the external electrode be improved. 
     SUMMARY 
     One object of the present invention is to provide a new type of laminated coil component capable of providing a high inductance and excellent in insulation reliability. Other objects of the present invention will be made apparent through description of the specification as a whole. 
     A laminated coil component according to one embodiment of the present invention is provided with a laminate, a first external electrode provided on a surface of the laminate, a second external electrode provided on a surface of the laminate, and a coil conductor having a plurality of conductor patterns. The laminate includes a plurality of insulating layers stacked in a predetermined direction. The coil conductor is formed so that a coil axis thereof agrees with a lamination direction of the plurality of insulating layers. 
     The above-described coil conductor is provided between the first external electrode and the second external electrode. The plurality of conductor patterns constituting the above-described coil conductor includes a conductor pattern (a1) in a first turn as counted from the first external electrode and a conductor pattern (aN) in an N-th turn as counted from the first external electrode. The conductor pattern (a1) may have one end thereof connected to a first lead-out conductor and be connected to the above-described first external electrode via the first lead-out conductor. The conductor pattern (aN) may have one end thereof connected to a second lead-out conductor and be connected to the above-described second external electrode via the second lead-out conductor. The above-described plurality of conductor patterns may further include a conductor pattern (am) on an m-th turn as counted from the first external electrode. The conductor pattern (am) has one end thereof connected to the above-described conductor pattern (a1) and the other end thereof connected to the above-described conductor pattern (aN). 
     In one embodiment of the present invention, the above-described coil conductor is configured so that a distance d(m) between the conductor pattern (am), among the plurality of conductor patterns, in the m-th turn (where m is any integer satisfying 2≤m≤N) as counted from the first external electrode and the second external electrode satisfies a relationship d(1)×(N−m+1)/N≤d(m)≤d(1) (where when m has a certain value, d(m) and d(1) have different values from each other). 
     In the above-described coil component, in a case where an electric current flows from the first external electrode toward the second external electrode, the electric current flows from the first external electrode to the above-described second external electrode by passing through the conductor pattern (a1), the conductor pattern (am), and the conductor pattern (aN) in this order. In this electric current path, since the conductor pattern (a1) is arranged more closely to the first external electrode than the conductor pattern (am), a potential difference between the conductor pattern (a1) and the second external electrode is larger than a potential difference between the conductor pattern (am) and the second external electrode. According to the above-described embodiment, since the relationship d(1)×(N−m+1)/N≤d(m)≤d(1) (where when m has a certain value, d(m) and d(1) have different values from each other) is satisfied, the conductor pattern (a1) having the largest potential difference from the above-described second external electrode is arranged farthest from the above-described second external electrode. For example, in a case where N=2, it follows that m=2, and thus the above inequality is expressed as d(1)×½≤d(2)≤d(1). Further, it is required that when m=2, d(2) and d(1) have different values from each other, and with this condition also taken into consideration, the above inequality is expressed as d(1)×½≤d(2)&lt;d(1). Consequently, the conductor pattern (a1) in the first turn as counted from the first external electrode is arranged farther from the second electrode than a conductor pattern (a2) in a second turn as counted from the first external electrode. Also in a case whereN&gt;3, similarly, the larger a potential difference a conductor pattern has from the second external electrode, the farther the conductor pattern is arranged from the above-described second external electrode. For example, in a case where N=3, the above inequality is expressed as d(1)×(4−m)/3≤d(m)≤d(1). Therefore, in a case where m=2, an inequality d(1)×⅔≤d(2)≤d(1) is established, and in a case where m=3, an inequality d(1)×⅓≤d(3)≤d(1) is established. When consideration is given to the condition that when m has a certain value, d(m) and d(1) have different values from each other, in a case where d(1)=d(2), it follows that d(3)≠d(1), and thus an inequality d(3)&lt;d(1) is established. In a case where d(1)=d(3), it follows that d(2)≠d(1), and thus an inequality d(2)&lt;d(1) is established. Therefore, a magnitude relationship among d(1), d(2), and d(3) in a case where N=3 is summarized as d(3)&lt;d(2)≤d(1) or d(2)&lt;d(3) s d(1). As thus described, a distance between the conductor pattern (a1) having a large potential difference from the second external electrode and the second external electrode is set to be large, and thus an insulation property between the above-described coil conductor and the above-described second external electrode is ensured. 
     In one embodiment of the present invention, the above-described coil conductor is configured so that a distance D(n) between a conductor pattern (bn), among the plurality of conductor patterns, in an n-th turn (where n is any integer satisfying 2≤n≤N) as counted from the second external electrode and the first external electrode satisfies a relationship D(1)×(N−m+1)/N≤D(n)≤D(1) (where when n has a certain value, D(n) and D(1) have different values from each other). 
     In the above-described coil component, in a case where an electric current flows from the second external electrode toward the first external electrode, the electric current flows from the above-described second external electrode to the above-described first external electrode by passing through a conductor pattern (b1), the conductor pattern (bn), and a conductor pattern (bN) in this order. In this electric current path, since the conductor pattern (b1) is arranged more closely to the second external electrode than the conductor pattern (bn), a potential difference between the conductor pattern (b1) and the first external electrode is larger than a potential difference between the conductor pattern (bn) and the first external electrode. According to the above-described embodiment, since the relationship D(1)×(N−m+1)/N≤D(n)≤D(1) (where when n has a certain value, D(n) and D(1) have different values from each other) is satisfied, the conductor pattern (b1) having the largest potential difference from the above-described first external electrode is arranged farthest from the above-described first external electrode. A magnitude relationship between D(1) and D(2) in a case where N=2 can be considered pursuant to the already described relationship between d(1) and d(2). A magnitude relationship among D(1), D(2), and D(3) in a case where N=3 can be considered pursuant to the already described relationship among d(1), d(2), and d(3). As thus described, a distance between the conductor pattern (b1) having a large potential difference from the first external electrode and the second external electrode is set to be large, and thus an insulation property between the above-described coil conductor and the above-described second external electrode is ensured. 
     In one embodiment of the present invention, when viewed from a direction of the coil axis, an inner periphery of each of the plurality of conductor patterns constituting the coil conductor extends along at least part of a closed loop surrounding the coil axis. Thus, a plane including the inner periphery of each of the plurality of conductor patterns extends parallel to a lamination direction in which the plurality of insulating layers are stacked. Therefore, a magnetic flux passing through a core defined by the inner peripheral surface of each of the plurality of conductor patterns is directed parallel to the lamination direction of the plurality of insulating layers. This can prevent a degradation in inductance due to a direction of a magnetic flux passing through the core being inclined with respect to the coil axis. 
     On the closed loop, there are a first position closest to the first external electrode and a second position closest to the second external electrode. As described above, the coil conductor is formed so that a distance between the conductor pattern (a1) and the second external electrode is larger than a distance between any other one (a conductor pattern (am)) of the plurality of conductor patterns and the second external electrode. Such a relationship is achieved by, for example, a technique in which, at the above-described second position, with the inner periphery of the above-described conductor pattern (a1) secured on the above-described closed loop, a dimension of the above-described conductor pattern (a1) in a width direction is reduced. In this case, at the second position, a direct current resistance (Rdc) of the conductor pattern (a1) is disadvantageously increased. As a solution to this, in one embodiment of the present invention, the conductor pattern (a1) is formed so that a cross-sectional area thereof at the above-described first position is equal to that at the above-described second position. Thus, the conductor pattern (a1) can be set so that a direct current resistance thereof at the first position is equal to that at the second position. 
     Advantages 
     According to the above-described embodiment, there is provided a laminated coil component capable of providing a high inductance and excellent in insulation reliability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a laminated coil component according to one embodiment of the present invention. 
         FIG.  2    is an exploded perspective view of the laminated coil component in  FIG.  1   . 
         FIG.  3   a    is a plan view of an insulating layer  11  in  FIG.  2   . 
         FIG.  3   b    is a plan view of an insulating layer  12  in  FIG.  2   . 
         FIG.  3   c    is a plan view of an insulating layer  13  in  FIG.  2   . 
         FIG.  3   d    is a plan view of an insulating layer  14  in  FIG.  2   . 
         FIG.  3   e    is a plan view of an insulating layer  15  in  FIG.  2   . 
         FIG.  3   f    is a plan view of an insulating layer  16  in  FIG.  2   . 
         FIG.  4    is a view schematically showing a cross section of the coil component in  FIG.  1    cut along a line I-I. 
         FIG.  5   a    is a sectional view of a first portion C 11   a  of a conductor pattern C 11  along a line II-II in  FIG.  3     a.    
         FIG.  5   b    is a sectional view of a third portion C 11   c  of the conductor pattern C 11  along a line III-Ill in  FIG.  3     a.    
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     By appropriately referring to the appended drawings, the following describes various embodiments of the present invention. Constituent elements common to a plurality of drawings are denoted by the same reference signs throughout the plurality of drawings. It should be noted that the drawings do not necessarily appear to an accurate scale for the sake of convenience of description. 
       FIG.  1    is a perspective view of a coil component  1  according to one embodiment of the present invention, and  FIG.  2    is an exploded perspective view of the coil component  1  shown in  FIG.  1   . 
     Each of these figures shows, as one example of the coil component  1 , a laminated inductor used as a passive element in various types of circuits. The laminated inductor is one example of a laminated coil component to which the present invention is applicable. The present invention can be applied to a power inductor incorporated into a power source line and other various types of laminated coil components. 
     The coil component  1  in the embodiment shown is provided with a laminate  10  including insulating layers stacked together, the insulating layers being made of a magnetic material, conductor patterns C 11  to C 16  embedded in the laminate  10 , an external electrode  21  electrically connected to one end of the conductor pattern C 11 , and an external electrode  22  electrically connected to one end of the conductor pattern C 16 . The conductor patterns C 11  to C 16  are each electrically connected to an adjacent one of the conductor patterns C 11  to C 16  via after-mentioned vias V 1  to V 5 , and the conductor patterns C 11  to C 16  connected together in this manner constitute a coil conductor  25 . The conductor pattern C 11  is connected to the external electrode  21  via an after-mentioned lead-out conductor  23 , and the conductor pattern C 16  is connected to the external electrode  22  via an after-mentioned lead-out conductor  24 . 
     As shown in the figures, in one embodiment of the present invention, the laminate  10  is formed in a substantially rectangular parallelepiped shape. The laminate  10  has a first principal surface  10   e , a second principal surface  10   f , a first end surface  10   a , a second end surface  10   c , a first side surface  10   b , and a second side surface  10   d . Outer surfaces of the laminate  10  are defined by these six surfaces. The first principal surface  10   e  and the second principal surface  10   f  are opposed to each other, the first end surface  10   a  and the second end surface  10   c  are opposed to each other, and the first side surface  10   b  and the second side surface  10   d  are opposed to each other. In a case where the laminate  10  is formed in a rectangular parallelepiped shape, the first principal surface  10   e  and the second principal surface  10   f  are parallel to each other, the first end surface  10   a  and the second end surface  10   c  are parallel to each other, and the first side surface  10   b  and the second side surface  10   d  are parallel to each other. 
     In the embodiment of  FIG.  1   , the first principal surface  10   e  lies on a top side of the laminate  10  and, therefore, may be referred to as a “top surface” in this specification. Similarly, the second principal surface  10   f  may be referred to as a “bottom surface.” In the coil component  1 , the second principal surface  10   f  is disposed so as to be opposed to a circuit board (not shown) and, therefore, may be referred to as a “mounting surface” in this specification. Furthermore, a top-bottom direction of the coil component  1  is based on a top-bottom direction in  FIG.  1   . 
     In this specification, a “length” direction, a “width” direction, and a “thickness” direction of the coil component  1  are referred to as an “L” axis direction, a “W” axis direction, and a “T” axis direction in  FIG.  1   , respectively, unless otherwise construed from the context. 
     In one embodiment of the present invention, the coil component  1  has a length (a dimension in the L axis direction) of 0.2 to 6.0 mm, a width (a dimension in the W axis direction) of 0.1 to 4.5 mm, and a thickness (a dimension in the T axis direction) of 0.1 to 4.0 mm. These dimensions are mere examples, and the coil component  1  to which the present invention is applicable can have any dimensions that conform to the purport of the present invention. In one embodiment, the coil component  1  has a low profile. For example, the coil component  1  has a width larger than a thickness thereof. 
       FIG.  2    is an exploded perspective view of the coil component  1  in  FIG.  1   . In  FIG.  2   , for the sake of convenience of illustration, the external electrode  21  and the external electrode  22  are not shown. As shown in the figure, the laminate  10  includes an insulator portion  20 , a top cover layer  18  provided on a top surface of the insulator portion  20 , and a bottom cover layer  19  provided on a bottom surface of the insulator portion  20 . The insulator portion  20  includes insulating layers  11  to  16  stacked together. The laminate  10  includes the top cover layer  18 , the insulating layer  11 , the insulating layer  12 , the insulating layer  13 , the insulating layer  14 , the insulating layer  15 , the insulating layer  16 , the insulating layer  17 , and the bottom cover layer  19  that are stacked in this order from top to bottom in  FIG.  2   . 
     The top cover layer  18  includes four insulating layers  18   a  to  18   d . The top cover layer  18  includes the insulating layer  18   a , the insulating layer  18   b , the insulating layer  18   c , and the insulating layer  18   d  that are stacked in this order from top to bottom in  FIG.  2   . 
     The bottom cover layer  19  includes four insulating layers  19   a  to  19   d . The bottom cover layer  19  includes the insulating layer  19   a , the insulating layer  19   b , the insulating layer  19   c , and the insulating layer  19   d  that are stacked in this order from top to bottom in  FIG.  2   . 
     As will be mentioned later, the insulating layers  11  to  16  have corresponding conductor patterns C 11  to C 16  formed thereon, respectively. The conductor patterns C 11  to C 16  and the lead-out conductors  23  and  24  constitute the coil conductor  25 . This coil conductor  25  has a coil axis A. The conductor patterns C 11  to C 16  are formed to extend around the coil axis A. In the embodiment shown, the coil axis A extends in the T axis direction, and the insulating layers  11  to  16  are stacked also in the T axis direction. A direction of the coil axis A, therefore, agrees with a lamination direction of the insulating layers  11  to  16 . 
     In another embodiment of the present invention, the insulating layers  11  to  16  may be stacked in the L axis direction. In this case, the conductor patterns C 11  to C 16  are formed on surfaces of the insulating layers  11  to  16 , respectively, and thus the coil axis A is oriented in the L axis direction, i.e. the same direction as the lamination direction of the insulating layers  11  to  16 . In still another embodiment of the present invention, the insulating layers  11  to  16  may be stacked in the W axis direction. In this case, the conductor patterns C 11  to C 16  are formed on the surfaces of the insulating layers  11  to  16 , respectively, and thus the coil axis A is oriented in the W axis direction, i.e. the same direction as the lamination direction of the insulating layers  11  to  16 . 
     A resin contained in the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d  is made of an insulating material. In one embodiment, the insulating material is a resin material having an excellent insulation property. As the resin material, for example, there can be used a polyvinyl butyral (PVB) resin, an ethyl cellulose resin, a polyvinyl alcohol resin, or an acrylic resin. The resin contained in the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d  may be a thermosetting resin having an excellent insulation property. As the thermosetting resin, for example, there can be used an epoxy resin, a polyimide resin, a polystyrene (PS) resin, a high-density polyethylene (HDPE) resin, a polyoxymethylene (POM) resin, a polycarbonate (PC) resin, a polyvinylidene fluoride (PVDF) resin, a phenolic resin, a polytetrafluoroethylene (PTFE) resin, or a polybenzoxazole (PBO) resin. The resin contained in each of the insulating layers and sheets may be a resin of the same type as in other insulating layers and sheets or a different type therefrom. 
     In a case where the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d  are formed of such a resin material, these insulating layers may contain filler particles. The filler particles are, for example, particles of a ferrite material, soft magnetic metal particles, particles of an inorganic material such as SiO 2  or Al 2 O 3 , or glass-based particles. Particles of a ferrite material applicable to the present invention are, for example, particles of Ni—Zn ferrite or particles of Ni—Zn—Cu ferrite. Soft magnetic metal particles applicable to the present invention are made of a material in which magnetism is developed in an unoxidized metal portion, and such soft magnetic metal particles are, for example, particles including unoxidized metal particles or alloy particles. Soft magnetic metal particles applicable to the present invention include particles of, for example, an Fe—Si—Cr, Fe—Si—Al, or Fe—Ni alloy, an Fe—Si—Cr—B—C or Fe—Si—B—Cr amorphous alloy, Fe, or a material obtained by mixing them. 
     The insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d  may be formed by combining a multitude of soft magnetic metal particles whose surfaces are coated with an insulating film. The insulating film is, for example, an oxide film formed by oxidizing a surface of a soft magnetic metal. Such an insulating layer formed of a multitude of soft magnetic metal particles thus combined is not required to contain a resin. Soft magnetic metal particles applicable to the present invention include particles of, for example, an Fe—Si—Cr, Fe—Si—Al, or Fe—Ni alloy, an Fe—Si—Cr—B—C or Fe—Si—B—Cr amorphous alloy, Fe, or a material obtained by mixing them. For example, Japanese Patent Application Publication No. 2013-153119 discloses a structure formed of soft magnetic metal particles, which can be used as each of the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d.    
     The coil component  1  can include any number of insulating layers as necessary in addition to the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d . Some of the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d  can be omitted as appropriate. 
     The conductor patterns C 11  to C 16  are each formed on a corresponding one of the insulating layers  11  to  16 . The conductor patterns C 11  to C 16  are formed by printing such as screen printing, plating, etching, or any other known method. Respective shapes and arrangements of the conductor patterns C 11  to C 16  will be described later. 
     The insulating layers  11  to  15  each include a corresponding one of the vias V 1  to V 5  formed at a predetermined position thereon. The vias V 1  to V 5  are formed by forming through-holes at the predetermined positions on the insulating layers  11  to  15  so as to extend through the insulating layers  11  to  15  in the T axis direction, respectively, and filling a metal material into the through-holes. 
     The conductor patterns C 11  to C 16  and the vias V 1  to V 5  are formed to contain a metal having excellent electrical conductivity and thus are made of, for example, Ag, Pd, Cu, Al, or any alloy of these metals. 
     Specific materials described in this specification are illustrative, and other materials not illustratively described in this specification can also be used as materials of the constituent elements of the coil component  1  as appropriate. 
     In one embodiment, the external electrode  21  is provided on the first end surface  10   a  of the laminate  10 , and the external electrode  22  is provided on the second end surface  10   c  of the laminate  10 . As shown in the figure, the external electrode  21  and the external electrode  22  may extend further onto the top surface  10   e , the bottom surface  10   f , the first side surface  10   b , and the second side surface  10   d  of the laminate  10 . In this case, in the laminate  10 , the external electrode  21  is provided so as to entirely cover the first end surface  10   a  and partly cover each of the top surface  10   e , the bottom surface  10   f , the first side surface  10   b , and the second side surface  10   d , and the external electrode  22  is provided so as to entirely cover the second end surface  10   c  and partly cover each of the top surface  10   e , the bottom surface  10   f , the first side surface  10   b , and the second side surface  10   d.    
     Next, with reference to  FIG.  3   a    to  FIG.  3   f    and  FIG.  4   , a further description is given of the coil component  1 .  FIG.  3   a    to  FIG.  3   f    are plan views of the insulating layers  11  to  16 , respectively.  FIG.  3   a    to  FIG.  3   f   , therefore, show the insulating layers  11  to  16 , respectively, as viewed from the direction of the coil axis A.  FIG.  4    is a view schematically showing a cross section of the coil component  1  cut along a line I-I in  FIG.  1   . 
     As shown in  FIG.  3   a   , the conductor pattern C 11  and the lead-out conductor  23  are formed on an upper surface of the insulating layer  11 . The lead-out conductor  23  extends inwardly from a vicinity of a middle of a side  11   a  in the W axis direction. The lead-out conductor  23  is formed so as to be electrically in contact with the external electrode  21 . 
     In one embodiment of the present invention, the conductor pattern C 11  is formed to extend, from an end portion of the lead-out conductor  23 , substantially ¾ of a turn in a clockwise direction along a closed loop B surrounding the coil axis A. The conductor pattern C 11  extends from a 9 o&#39;clock position to a 6 o&#39;clock position in the clockwise direction along the closed loop B. The conductor pattern C 11  has an inner peripheral surface C 11   g  and an outer peripheral surface C 11   h . The conductor pattern C 11  is formed so that, when viewed from the direction of the coil axis A, the inner peripheral surface dig thereof extends along part of the closed loop B (part of a side Ba, an entire length of a side Bb, an entire length of a side Bc, and part of a side Bd). 
     In the embodiment shown, the closed loop B has a shape corresponding to sides of a rectangular through which the coil axis A extends. Specifically, the closed loop B includes the side Ba extending parallel to the side  11   a  of the insulating layer  11 , the side Bb connected to one end of the side Ba and extending parallel to a side  11   b  of the insulating layer  11 , the side Bc connected to one end of the side Bb and extending parallel to a side  11   c  of the insulating layer  11 , and the side Bd connected to one end of the side Bc and extending parallel to a side  11   d  of the insulating layer  11 . The closed loop B can assume various shapes in addition to a rectangular shape. The closed loop B can assume, for example, a shape corresponding to a circumference of a circle, a shape corresponding to a circumference of an ellipse, a shape corresponding to sides of a rectangle or any other type of polygon, or other various shapes. 
     In the embodiment shown, the conductor pattern C 11  has a first portion C 11   a  extending in a W axis positive direction from a right end of the lead-out conductor  23 , a second portion C 11   b  extending in an L axis negative direction from an upper end of the first portion C 11   a , a third portion C 11   c  extending in a W axis negative direction from a right end of the second portion C 11   b , and a fourth portion C 11   d  extending in an L axis positive direction from a lower end of the third portion C 11   c.    
     As shown in the figure, the first portion C 11   a  of the conductor pattern C 11  has a width W 1   a  and is formed so that a spacing d 1   a  is provided between an outer periphery thereof and the side  11   a . Part of the external electrode  21  extends along the side  11   a , and thus a spacing between the outer periphery of the first portion C 11   a  and the external electrode  21  corresponds to the spacing d 1   a.    
     The second portion C 11   b  has a wide portion connected to the first portion C 11   a  and a narrow portion connected to the third portion C 11   c . The second portion C 11   b  may be formed and disposed so that the wide portion is opposed to the external electrode  21  and the narrow portion is opposed to the external electrode  22 . The wide portion of the second portion C 11   b  has a width W 1   b   1  and is formed so that a spacing d 1   b   1  is provided between an outer periphery thereof and the side  11   b . Part of the external electrode  21  extends along the side  11   b , and thus a spacing between an outer periphery of the second portion C 11   b  and the external electrode  21  corresponds to the spacing d 1   b   1 . The narrow portion of the second portion C 11   b  has a width W 1   b   2  and is formed so that a spacing d 1   b   2  is provided between an outer periphery thereof and the side  11   b . Part of the external electrode  22  extends along the side  11   b , and thus a spacing between the outer periphery of the second portion C 11   b  and the external electrode  22  corresponds to the spacing d 1   b   2 . 
     The third portion C 11   c  is has a width W 1   c  and is formed so that a spacing d 1   c  is provided between an outer periphery thereof and the side  11   c . Part of the external electrode  22  extends along the side  11   c , and thus a spacing between the outer periphery of the third portion C 11   c  and the external electrode  22  corresponds to the spacing d 1   c.    
     The fourth portion C 11   d  has a narrow portion connected to the third portion C 11   c  and a wide portion extending in the L axis positive direction from an end portion of the narrow portion. The fourth portion C 11   d  may be formed and disposed so that the wide portion is opposed to the external electrode  22 . The narrow portion of the fourth portion C 11   d  has a width W 1   d   1  and is formed so that a spacing d 1   d   1  is provided between an outer periphery thereof and the side  11   d . The wide portion of the fourth portion C 11   d  has a width W 1   d   2  and is formed so that a spacing d 1   d   2  is provided between an outer periphery thereof and the side  11   d . Part of the external electrode  22  extends along the side  11   d , and thus a spacing between an outer periphery of the fourth portion C 11   d  and the external electrode  22  corresponds to the spacing d 1   d   1 . 
     In one embodiment of the present invention, the conductor pattern C 11  is formed and disposed so that the spacing d 1   c  between the outer periphery of the third portion C 11   c  and the external electrode  22  is smaller than the spacing d 1   b   2  between the outer periphery of the second portion C 11   b  and the external electrode  22  and the spacing d 1   d   1  between the outer periphery of the fourth portion C 11   d  and the external electrode  22 . 
     As shown in  FIG.  4   , the conductor pattern C 11  is formed at a spacing die from the top surface  10   e  of the laminate  10 . Part of the external electrode  22  extends along the top surface  10   e  of the laminate  10 , and thus a spacing between the conductor pattern C 11  and the external electrode  22  corresponds to the spacing d 1   e . In one embodiment of the present invention, the conductor pattern C 11  is formed and disposed so that d 1   c &lt;d 1   e.    
     A width of the conductor pattern C 11  refers to a dimension of the conductor pattern C 11  in a direction perpendicular to an extending direction of the conductor pattern C 11  (a direction in which the conductor pattern C 11  extends along the closed loop B). Widths of the other conductor patterns are also to be understood to have a similar meaning. 
     As shown in  FIG.  3   b   , the conductor pattern C 12  is formed on an upper surface of the insulating layer  12 . The conductor pattern C 12  is electrically connected to the conductor pattern C 11  via the via V 1 . 
     The conductor pattern C 12  is formed to extend, from a position where it is connected to the via V 1 , substantially ½ of a turn clockwise along the closed loop B. The conductor pattern C 12  extends from a 6 o&#39;clock position to a 12 o&#39;clock position in the clockwise direction along the closed loop B. 
     The conductor pattern C 12  has an inner peripheral surface C 12   g  and an outer peripheral surface C 12   h . In an embodiment shown, the conductor pattern C 12  is formed so that the inner peripheral surface C 12   g  thereof extends along part of the closed loop B (part of the side Bd, an entire length of the side Ba, and part of the side Bb). Specifically, the conductor pattern C 12  has a first portion C 12   d  extending in the L axis positive direction from a connection position with the via V 1 , a second portion C 12   a  extending in the W axis positive direction from a left end of the first portion C 12   d , and a third portion C 12   b  extending in the L axis negative direction from an upper portion of the second portion C 12   a.    
     The first portion C 12   d  of the conductor pattern C 12  has a width W 2   d  and is formed so that a spacing d 2   d  is provided between an outer periphery thereof and a side  12   d . The second portion C 12   a  has a width W 2   a  and is formed so that a spacing d 2   a  is provided between an outer periphery thereof and a side  12   a . The third portion C 12   b  has a width W 2   b  and is formed so that a spacing d 2   b  is provided between an outer periphery thereof and a side  12   b.    
     As shown in  FIG.  3   c   , the conductor pattern C 13  is formed on an upper surface of the insulating layer  13 . The conductor pattern C 13  is electrically connected to the conductor pattern C 12  via the via V 2 . In an embodiment shown, the conductor pattern C 13  is formed to extend, from a position where it is connected to the via V 2 , substantially ½ of a turn clockwise along the closed loop B. The conductor pattern C 13  extends from a 12 o&#39;clock position to a 6 o&#39;clock position in the clockwise direction along the closed loop B. 
     The conductor pattern C 13  has an inner peripheral surface C 13   g  and an outer peripheral surface C 13   h . The conductor pattern C 13  is formed so that the inner peripheral surface C 13   g  thereof extends along part of the closed loop B (part of the side Bb, an entire length of the side Bc, and part of the side Bd). Specifically, the conductor pattern C 13  has a first portion C 13   b  extending in the L axis negative direction from a connection position with the via V 2 , a second portion C 13   c  extending in the W axis negative direction from a right end of the first portion C 13   b , and a third portion C 13   d  extending in the L axis positive direction from a lower end of the second portion C 13   c.    
     The first portion C 13   b  of the conductor pattern C 13  has a width W 3   b  and is formed so that a spacing d 3   b  is provided between an outer periphery thereof and a side  13   b . The second portion C 13   c  has a width W 3   c  and is formed so that a spacing d 3   c  is provided between an outer periphery thereof and a side  13   c . The third portion C 13   d  has a width W 3   d  and is formed so that a spacing d 3   d  is provided between an outer periphery thereof and a side  13   d.    
     As shown in  FIG.  3   d   , the conductor pattern C 14  is formed on an upper surface of the insulating layer  14 . The conductor pattern C 14  is electrically connected to the conductor pattern C 13  via the via V 3 . The conductor pattern C 14  is formed in substantially the same shape as that of the conductor pattern C 12 . In an embodiment shown, the conductor pattern C 14  is formed to extend, from a position where it is connected to the via V 3 , substantially ½ of a turn clockwise along the closed loop B. The conductor pattern C 14  extends from a 6 o&#39;clock position to a 12 o&#39;clock position in the clockwise direction along the closed loop B. 
     The conductor pattern C 14  has an inner peripheral surface C 14   g  and an outer peripheral surface C 14   h . The conductor pattern C 14  is formed so that the inner peripheral surface C 14   g  thereof extends along part of the closed loop B (part of the side Bd, the entire length of the side Ba, and part of the side Bb). Specifically, the conductor pattern C 14  has a first portion C 14   d  extending in the L axis positive direction from a connection position with the via V 3 , a second portion C 14   a  extending in the W axis positive direction from a left end of the first portion C 14   d , and a third portion C 14   b  extending in the L axis negative direction from an upper end of the second portion C 14   a.    
     The first portion C 14   d  of the conductor pattern C 14  has a width W 4   d  and is formed so that a spacing d 4   d  is provided between an outer periphery thereof and a side  14   d . The second portion C 14   a  has a width W 4   a  and is formed so that a spacing d 4   a  is provided between an outer periphery thereof and a side  14   a . The third portion C 14   b  has a width W 4   b  and is formed so that a spacing d 4   b  is provided between an outer periphery thereof and a side  14   b.    
     As shown in  FIG.  3   e   , the conductor pattern C 15  is formed on an upper surface of the insulating layer  15 . The conductor pattern C 15  is electrically connected to the conductor pattern C 14  via the via V 4 . In an embodiment shown, the conductor pattern C 15  is formed to extend, from a position where it is connected to the via V 4 , substantially ½ of a turn clockwise along the closed loop B. The conductor pattern C 15  extends from a 12 o&#39;clock position to a 6 o&#39;clock position in the clockwise direction along the closed loop B. 
     The conductor pattern C 15  has an inner peripheral surface C 15   g  and an outer peripheral surface C 15   h . The conductor pattern C 15  is formed so that the inner peripheral surface C 15   g  thereof extends along part of the closed loop B (part of the side Bb, the entire length of the side Bc, and part of the side Bd). Specifically, the conductor pattern C 15  has a first portion C 15   b  extending in the L axis negative direction from a connection position with the via V 4 , a second portion C 15   c  extending in the W axis negative direction from a right end of the first portion C 15   b , and a third portion C 15   d  extending in the L axis positive direction from a lower end of the second portion C 15   c.    
     The first portion C 15   b  of the conductor pattern C 15  has a width W 5   b  and is formed so that a spacing d 5   b  is provided between an outer periphery thereof and a side  15   b . The second portion C 15   c  has a width W 5   c  and is formed so that a spacing d 5   c  is provided between an outer periphery thereof and a side  15   c . The third portion C 15   d  has a width W 5   d  and is formed so that a spacing d 5   d  is provided between an outer periphery thereof and a side  15   d.    
     As shown in  FIG.  3   f   , the conductor pattern C 16  and the lead-out conductor  24  are formed on an upper surface of the insulating layer  16 . The conductor pattern C 16  is electrically connected to the conductor pattern C 15  via the via V 5 . The lead-out conductor  24  extends inwardly from a vicinity of a middle of a side  16   c  in the W axis direction. The lead-out conductor  24  is formed so as to be electrically in contact with the external electrode  22 . 
     In an embodiment shown, the conductor pattern C 16  is formed to extend, from a position where it is connected to the via V 5 , substantially ¾ of a turn clockwise along the closed loop B. The conductor pattern C 16  extends from a 6 o&#39;clock position to a 3 o&#39;clock position in the clockwise direction along the closed loop B. One end of the conductor pattern C 16  is connected to an end portion of the lead-out conductor  24 . 
     The conductor pattern C 16  has an inner peripheral surface C 16   g  and an outer peripheral surface C 16   h . The conductor pattern C 16  is formed so that the inner peripheral surface C 16   g  thereof extends along part of the closed loop B (part of the side Bd, the entire lengths of the side Ba and the side Bb, and part of the side Bc). Specifically, the conductor pattern C 16  has a first portion C 16   d  extending in the L axis positive direction from a connection position with the via V 5 , a second portion C 16   a  extending in the W axis positive direction from a left end of the first portion C 16   d , a third portion C 16   b  extending in the L axis negative direction from an upper end of the second portion C 16   a , and a fourth portion C 16   c  extending in the W axis negative direction from a right end of the third portion C 16   b.    
     As shown in the figure, the first portion C 16   d  of the conductor pattern C 16  has a wide portion extending in the L axis positive direction from the connection position with the via V 5  and a narrow portion extending from a left end of the wide portion to a connection position with the second portion C 16   a . The first portion C 16   d  may be formed and disposed so that the narrow portion is opposed to the external electrode  21 . The wide portion of the first portion C 16   d  has a width W 6   d   1  and is formed so that a spacing d 6   d   1  is provided between an outer periphery thereof and a side  16   d . The narrow portion of the first portion C 16   d  has a width W 6   d   2  and is formed so that a spacing d 6   d   2  is provided between an outer periphery thereof and the side  16   d . Part of the external electrode  21  extends along the side  16   d , and thus a spacing between an outer periphery of the first portion C 16   d  and the external electrode  21  corresponds to the spacing d 6   d   2 . 
     The second portion C 16   a  has a width W 6   a  and is formed so that a spacing d 6   a  is provided between an outer periphery thereof and a side  16   a . Part of the external electrode  21  extends along the side  16   a , and thus a spacing between the outer periphery of the second portion C 16   a  and the external electrode  21  corresponds to the spacing d 6   a.    
     The third portion C 16   b  has a narrow portion extending in the L axis negative direction from the second portion C 16   a  and a wide portion extending from a right end of the narrow portion to a connection position with the fourth portion C 16   c . The third portion C 16   b  may be formed and disposed so that the narrow portion is opposed to the external electrode  21  and the wide portion is opposed to the external electrode  22 . The narrow portion of the third portion C 16   b  has a width W 6   b   1  and is formed so that a spacing d 6   b   1  is provided between an outer periphery thereof and a side  16   b . Part of the external electrode  21  extends along the side  16   b , and thus a spacing between an outer periphery of the third portion C 16   b  and the external electrode  21  corresponds to the spacing d 6   b   1 . The wide portion of the third portion C 16   b  has a width W 6   b   2  and is formed so that a spacing d 6   b   2  is provided between an outer periphery thereof and the side  16   b . Part of the external electrode  22  extends along the side  16   b , and thus a spacing between the outer periphery of the third portion C 16   b  and the external electrode  22  corresponds to the spacing d 6   b   2 . 
     The fourth portion C 16   c  has a width W 6   c  and is formed so that a spacing d 6   c  is provided between an outer periphery thereof and a side  16   c . Part of the external electrode  22  extends along the side  16   c , and thus a spacing between the outer periphery of the fourth portion C 16   c  and the external electrode  22  corresponds to the spacing d 6   c.    
     In one embodiment of the present invention, the conductor pattern C 16  is formed and disposed so that the spacing d 6   a  between the outer periphery of the second portion C 16   a  and the external electrode  21  is larger than the spacing d 6   d   2  between the outer periphery of the first portion C 16   d  and the external electrode  21  and the spacing d 6   b   1  between the outer periphery of the third portion C 16   b  and the external electrode  21 . 
     As shown in  FIG.  4   , the conductor pattern C 16  is formed at a spacing d 6   f  from the bottom surface  10   f  of the laminate  10 . Part of the external electrode  21  extends along the bottom surface  10   f  of the laminate  10 , and thus a spacing between the conductor pattern C 16  and the external electrode  21  corresponds to the spacing d 6   f . In one embodiment of the present invention, the conductor pattern C 16  is formed and disposed so that d 6   a &lt;d 6   f.    
     As mentioned above, in the embodiment shown, the coil conductor  25  is constituted of the conductor patterns C 11  to C 16 . Each of the conductor patterns C 11  and C 16  is wound ¾ of a turn around the coil axis A, and each of the conductor patterns C 12  to C 15  is wound ½ of a turn around the coil axis A. The coil conductor  25  formed by joining the conductor patterns C 11  to C 16  together is, therefore, wound 3.5 turns around the coil axis A. 
     In the coil conductor  25 , a conductor pattern in a first turn as counted from the external electrode  21  is constituted of the entire conductor pattern C 11  and a portion of the conductor pattern C 12  extending clockwise from a connection point with the via V 1  to a position superimposed in plan view on a winding start position of the conductor pattern C 11  (a position where the conductor pattern C 11  is connected to the lead-out conductor  23 ). In the embodiment shown, the conductor pattern in the first turn as counted from the external electrode  21  is constituted of the entire conductor pattern C 11  and a portion of the conductor pattern C 12  extending 90° clockwise from the connection point with the via V 1  (a portion of the conductor pattern C 12  extending from a 6 o&#39;clock position to a 9 o&#39;clock position). 
     Similarly to the conductor pattern in the first turn, a conductor pattern in a second turn as counted from the external electrode  21  is constituted of a portion of the conductor pattern C 12  extending clockwise from a connection point with the conductor pattern in the first turn to the via V 2 , the entire conductor pattern C 13 , and a portion of the conductor pattern C 14  extending clockwise from a connection point with the via V 3  to a position superimposed in plan view on the winding start position of the conductor pattern C 11 . In the embodiment shown, the conductor pattern in the second turn as counted from the external electrode  21  is constituted of a portion of the conductor pattern C 12  extending 90° clockwise from the connection point with the conductor pattern in the first turn (a portion of the conductor pattern C 12  extending from a 9 o&#39;clock position to a 12 o&#39;clock position), the entire conductor pattern C 13 , and a portion of the conductor pattern C 14  extending 90° clockwise from the connection point with the via V 3  (a portion of the conductor pattern C 14  extending from a 6 o&#39;clock position to a 9 o&#39;clock position). Similarly, a conductor pattern in a third turn as counted from the external electrode  21  is constituted of a portion of the conductor pattern C 14  extending from a connection point with the conductor pattern in the second turn to the via V 4 , the entire conductor pattern C 15 , and a portion of the conductor pattern C 16  extending from a connection point with the via V 5  to a position superimposed in plan view on the winding start position of the conductor pattern C 11 . In the embodiment shown, the conductor pattern in the third turn as counted from the external electrode  21  is constituted of a portion of the conductor pattern C 14  extending 90° clockwise from the connection point with the conductor pattern in the second turn (a portion of the conductor pattern C 14  extending from a 9 o&#39;clock position to a 12 o&#39;clock position), the entire conductor pattern C 15 , and a portion of the conductor pattern C 16  extending 90° clockwise from the connection point with the via V 5  (a portion of the conductor pattern C 16  extending from a 6 o&#39;clock position to a 9 o&#39;clock position). Lastly, a conductor pattern in a fourth turn as counted from the external electrode  21  is constituted of a portion of the conductor pattern C 16  extending clockwise from a connection point with the conductor pattern in the third turn to a connection position with the lead-out conductor  24 . In the embodiment shown, the conductor pattern in the fourth turn as counted from the external electrode  21  is constituted of a portion of the conductor pattern C 16  extending 90° clockwise from the connection point with the conductor pattern in the third turn (a portion of the conductor pattern C 16  extending from a 9 o&#39;clock position to a 3 o&#39;clock position). As thus described, the conductor pattern in the fourth turn as counted from the external electrode  21  is formed of a conductor pattern in the coil conductor  25 , which extends from the connection point with the conductor pattern in the third turn to a position where the coil conductor  25  is wound 0.5 turns from that connection point. That is, in the embodiment shown, the conductor pattern in the fourth turn is constituted of a conductor pattern of less than one turn. The conductor pattern in the fourth turn may be constituted of a conductor pattern of exactly one turn or a conductor pattern of less than one turn. 
     In this specification, the conductor pattern in the first turn as counted from the external electrode  21  may be referred to as a conductor pattern (a1). Furthermore, more generally, a conductor pattern in an m-th turn as counted from the external electrode  21  may be referred to as a conductor pattern (am). In this case, m is any positive integer. In a case where the conductor pattern (am) is assumed to exclude the conductor pattern in the first turn, m is a positive integer equal to or higher than two. An upper limit of m is a maximum number of turns of the coil conductor  25 . In the embodiment shown, the coil conductor  25  is wound 3.5 turns, and thus the maximum number of turns thereof is 4. Accordingly, the upper limit of m is also 4. When, however, reference is made to a conductor pattern (a(m+1)) in a subsequent turn following the conductor pattern (am), the upper limit of m is set to a number obtained by subtracting 1 from the maximum number of turns. 
     In the coil conductor  25 , a conductor pattern in a first turn as counted from the external electrode  22  is constituted of the entire conductor pattern C 16  and a portion of the conductor pattern C 15  extending counterclockwise from a connection point with the via V 5  to a position superimposed in plan view on a winding start position of the conductor pattern C 16  (a position where the conductor pattern C 16  is connected to the lead-out conductor  24 ). In the embodiment shown, the conductor pattern in the first turn as counted from the external electrode  22  is constituted of the entire conductor pattern C 16  and a portion of the conductor pattern C 15  extending 90° counterclockwise from the connection point with the via V 5  (a portion of the conductor pattern C 15  extending from a 6 o&#39;clock position to a 3 o&#39;clock position). Similarly, a conductor pattern in a second turn as counted from the external electrode  22  is constituted of a portion of the conductor pattern C 15  extending counterclockwise from a connection point with the conductor pattern in the first turn to the via V 4 , the entire conductor pattern C 14 , and a portion of the conductor pattern C 13  extending counterclockwise from a connection point with the via V 3  to a position superimposed in plan view on the winding start position of the conductor pattern C 16 . In the embodiment shown, the conductor pattern in the second turn as counted from the external electrode  22  is constituted of a portion of the conductor pattern C 15  extending 90° counterclockwise from the connection point with the conductor pattern in the first turn (a portion of the conductor pattern C 15  extending from a 3 o&#39;clock position to a 12 o&#39;clock position), the entire conductor pattern C 14 , and a portion of the conductor pattern C 13  extending 90° counterclockwise from the connection point with the via V 3  (a portion of the conductor pattern C 13  extending from a 6 o&#39;clock position to a 3 o&#39;clock position). Similarly, a conductor pattern in a third turn as counted from the external electrode  22  is constituted of a portion of the conductor pattern C 13  extending counterclockwise from a connection point with the conductor pattern in the second turn to the via V 2 , the entire conductor pattern C 12 , and a portion of the conductor pattern C 11  extending from a connection point with the via V 1  to a position superimposed in plan view on the winding start position of the conductor pattern C 16 . In the embodiment shown, the conductor pattern in the third turn as counted from the external electrode  22  is constituted of a portion of the conductor pattern C 13  extending 90° counterclockwise from the connection point with the conductor pattern in the second turn (a portion of the conductor pattern C 13  extending from a 3 o&#39;clock position to a 12 o&#39;clock position), the entire conductor pattern C 12 , and a portion of the conductor pattern C 11  extending 90° counterclockwise from the connection point with the via V 1  (a portion of the conductor pattern C 11  extending from a 6 o&#39;clock position to a 3 o&#39;clock position). Lastly, a conductor pattern in a fourth turn as counted from the external electrode  22  is constituted of a portion of the conductor pattern C 11  extending counterclockwise from a connection point with the conductor pattern in the third turn to a connection position with the lead-out conductor  23 . In the embodiment shown, the conductor pattern in the fourth turn as counted from the external electrode  22  is constituted of a portion of the conductor pattern C 11  extending 90° counterclockwise from the connection point with the conductor pattern in the third turn (a portion of the conductor pattern C 11  extending from a 3 o&#39;clock position to a 9 o&#39;clock position). As thus described, the conductor pattern in the fourth turn as counted from the external electrode  22  is formed of a conductor pattern in the coil conductor  25 , which extends from the connection point with the conductor pattern in the third turn to a position where the coil conductor  25  is wound 0.5 turns from that connection point. That is, in the embodiment shown, the conductor pattern in the fourth turn is constituted of a conductor pattern of less than one turn. The conductor pattern in the fourth turn may be constituted of a conductor pattern of exactly one turn or a conductor pattern of less than one turn. 
     In this specification, the conductor pattern in the first turn as counted from the external electrode  22  may be referred to as a conductor pattern (b1). Furthermore, more generally, a conductor pattern in an n-th turn as counted from the external electrode  22  may be referred to as a conductor pattern (bn). In this case, n is any positive integer. In a case where the conductor pattern (bn) is assumed to exclude the conductor pattern in the first turn, n is a positive integer equal to or higher than two. An upper limit of n is a maximum number of turns of the coil conductor  25 . In the embodiment shown, the coil conductor  25  is wound 3.5 turns, and thus the maximum number of turns thereof is 4. Accordingly, in this case, the upper limit of n is also 4. When, however, reference is made to a conductor pattern (b(n+1)) in a subsequent turn following the conductor pattern (bn), the upper limit of n is set to a number obtained by subtracting 1 from the maximum number of turns. 
     While the conductor patterns in the first turn, the second turn, and the third turn as counted from the external electrode  21  each extend one turn around the coil axis A, the conductor pattern in the fourth turn extends half a turn around the coil axis A. Similarly, while the conductor patterns in the first turn, the second turn, and the third turn as counted from the external electrode  22  each extend one turn around the coil axis A, the conductor pattern in the fourth turn extends half a turn around the coil axis A. 
     The coil conductor  25  in one embodiment of the present invention is configured so that, where a maximum number of turns of the coil conductor  25  is N, a distance d(m) between the conductor pattern (am) in the m-th turn as counted from the external electrode  21  and the second external electrode  22  satisfies a relationship d(1)×(N−m+1)/N≤d(m)≤d(1) (where when m has a certain value, d(m) and d(1) have different values from each other)(where 2≤m). In this specification, a distance between a predetermined conductor pattern and the external electrode  22  refers to the smallest among spacings between the conductor pattern and the external electrode  22 . 
     As described above, in the embodiment shown, the conductor pattern (a1) in the first turn as counted from the external electrode  21  has the entire conductor pattern C 11  and the portion of the conductor pattern C 12  extending 90° clockwise from the connection point with the via V 1 . In the embodiment shown, at least part of the conductor pattern C 11  is arranged more closely to the external electrode  22  than the conductor pattern C 12 . Therefore, as a distance between the conductor pattern (a1) in the first turn and the external electrode  22 , the smallest among the spacings d 1   c , d 1   b   2 , d 1   d   1 , and d 1   e  between the various portions of the conductor pattern C 11  and the external electrode  22  is used. The distance between the conductor pattern (a1) and the external electrode  22  is set so that an insulation property between the conductor pattern (a1) and the external electrode  22  is ensured. 
     In one embodiment of the present invention, as mentioned above, the conductor pattern C 11  is formed and disposed so that the spacing d 1   c  is the smallest among the spacings d 1   c , d 1   b   2 , d 1   d   1 , and d 1   e . In this case, the distance between the conductor pattern (a1) in the first turn and the external electrode  22  is equal to the spacing d 1   c  between the third portion C 11   c  and the external electrode  22 . 
     In another embodiment of the present invention, the conductor pattern C 11  can be formed and disposed so that, among the spacings d 1   c , d 1   b   2 , d 1   d   1 , and d 1   e , any one of them other than the spacing d 1   c  is the smallest. For example, when the spacing d 1   b   2  is the smallest among the spacings d 1   c , d 1   b   2 , d 1   d   1  and die, the distance between the conductor pattern (a1) and the external electrode  22  corresponds to the spacing d 1   b   2 . When the spacing d 1   d   1  is the smallest among them, the distance between the conductor pattern (a1) and the external electrode  22  corresponds to the spacing d 1   d   1 . When the spacing d 1   e  is the smallest among them, the distance between the conductor pattern (a1) and the external electrode  22  corresponds to the spacing d 1   e.    
     A distance between each of the conductor patterns in the second and subsequent turns and the external electrode  22  is also defined similarly to the distance between the conductor pattern (a1) in the first turn and the external electrode  22 . That is, a distance between the conductor pattern (am) in the m-th turn as counted from the external electrode  21  and the external electrode  22  refers to the smallest among the spacings between the conductor pattern (am) and the external electrode  22 . The distance between the conductor pattern (am) and the external electrode  22  is set so that an insulation property between the conductor pattern (am) and the external electrode  22  is ensured. 
     In the embodiment shown, N=4 and d(1)=d 1   c , and thus the distance d(m) between the conductor pattern (am) and the external electrode  22  is expressed as d 1   c ×(5−m)/4≤d(m)≤d 1   c . In order to satisfy this relationship, in a case of a distance d(2) between the conductor pattern in the second turn as counted from the external electrode  21  and the external electrode  22 , since m=2, an inequality d 1   c ×¾≤d(2)≤d 1   c  is established. In a case where the distance d(2) between the conductor pattern in the second turn and the external electrode  22  is equal to the spacing d 3   c  between the conductor pattern C 13  and the external electrode  22 , an inequality d 1   c ×¾≤ d 3   c ≤ d 1   c  is established. Similarly, in a case of a distance d(3) between the conductor pattern in the third turn as counted from the external electrode  21  and the external electrode  22 , since m=3, an inequality d 1   c ×½≤d(3)≤d 1   c  is established. In a case where the distance d(3) between the conductor pattern in the third turn and the external electrode  22  is equal to the spacing d 5   c  between the conductor pattern C 15  and the external electrode  22 , an inequality d 1   c ×½≤d 5   c ≤d 1   c  is established. Similarly, in a case of a distance d(4) between the conductor pattern in the fourth turn as counted from the external electrode  21  and the external electrode  22 , since m=4, an inequality d 1   c ×¼≤d(4)≤ d 1   c  is established. In a case where the distance d(4) between the conductor pattern in the fourth turn and the external electrode  22  is equal to the spacing d 6   c  between the conductor pattern C 16  and the external electrode  22 , an inequality d 1   c ×¼≤d 6   c ≤d 1   c  is established. It is, however, also required to satisfy the condition that when m has a certain value, d(m) and d (1) have different values from each other, and thus d(1) (=d 1   c ) has a value different from at least one of respective values of d(2), d(3), and d(4). 
     In this electric current path linking the external electrode  21  to the external electrode  22 , since the conductor pattern (a1) is arranged more closely to the external electrode  21  than the conductor pattern (am), when a voltage is applied between the external electrode  21  and the external electrode  22 , a potential difference between the conductor pattern (a1) and the external electrode  22  is larger than a potential difference between the conductor pattern (am) and the external electrode  22 . According to the above-described embodiment, since the relationship d(1)×(N−m+1)/N≤d(m)≤d(1) (where when m has a certain value, d(m) and d(1) have different values from each other) is satisfied, the conductor pattern (a1) having the largest potential difference from the external electrode  22  is arranged farthest from the external electrode  22 . As described above, a distance d(1) between the conductor pattern (a1) and the external electrode  22  is set so that an insulation property between the conductor pattern (a1) and the external electrode  22  is ensured. As thus described, the distance between the conductor pattern (a1) having a large potential difference from the external electrode  22  and the external electrode  22  is set to be large, and thus an insulation property between the conductor pattern (a1) and the external electrode  22  is ensured. Even though a distance between the conductor pattern (am) and the external electrode  22  is equal to or less than a value of d(1), an insulation property between the conductor pattern (am) and the external electrode  22  can be ensured. 
     The coil conductor  25  in one embodiment of the present invention is configured so that, where a maximum number of turns of the coil conductor  25  is N, a distance D(n) between the conductor pattern (bn) in the n-th turn as counted from the external electrode  22  and the external electrode  21  satisfies a relationship D(1)×(N−m+1)/N≤ D(n)≤D(1) (where when n has a certain value, D(n) and D(1) have different values from each other)(where 2≤n). 
     As described above, in the embodiment shown, the conductor pattern (b1) in the first turn as counted from the external electrode  22  has the entire conductor pattern C 16  and a portion of the conductor pattern C 15  extending 90° counterclockwise from the connection point with the via V 5 . In the embodiment shown, at least part of the conductor pattern C 16  is arranged more closely to the external electrode  21  than the conductor pattern C 15 . Therefore, as a distance between the conductor pattern (b1) in the first turn and the external electrode  21 , the smallest among the spacings d 6   a, d   6   b   1 , d 6   d   2 , and d 6   f  between the various portions of the conductor pattern C 16  and the external electrode  21  is used. The distance between the conductor pattern (b) and the external electrode  21  is set so that an insulation property between the conductor pattern (b1) and the external electrode  21  is ensured. 
     In one embodiment of the present invention, as mentioned above, the conductor pattern C 16  is formed and disposed so that the spacing d 6   a  is the smallest among the spacings d 6   a, d   6   b   1 , d 6   d   2 , and d 6   f . In this case, the distance between the conductor pattern (b1) in the first turn and the external electrode  21  is equal to the spacing d 6   a  between the second portion C 16   a  and the external electrode  21 . 
     A distance between each of the conductor patterns in the second and subsequent turns and the external electrode  21  is also defined similarly to the distance between the conductor pattern (b1) in the first turn and the external electrode  21 . That is, a distance between the conductor pattern (bn) in the n-th turn as counted from the external electrode  22  and the external electrode  21  refers to the smallest among the spacings between the conductor pattern (bn) and the external electrode  21 . The distance between the conductor pattern (bn) and the external electrode  21  is set so that an insulation property between the conductor pattern (bn) and the external electrode  21  is ensured. 
     In another embodiment of the present invention, the conductor pattern C 16  can be formed and disposed so that, among the spacings d 6   a, d   6   b   1 , d 6   d   2 , and d 6   f , any one of them other than the spacing d 6   a  is the smallest. For example, when the spacing d 6   b   1  is the smallest among the spacings d 6   a, d   6   b   1 , d 6   d   2 , and d 6   f , the distance between the conductor pattern (b1) and the external electrode  21  corresponds to the spacing d 6   b   1 . When the spacing d 6   d   2  is the smallest among them, the distance between the conductor pattern (b1) and the external electrode  21  corresponds to the spacing d 6   d   2 . When the spacing d 6   f  is the smallest among them, the distance between the conductor pattern (b1) and the external electrode  21  corresponds to the spacing d 6   f.    
     In the embodiment shown, N=4 and D(1)=d 6   a , and thus a distance D(n) between the conductor pattern (bn) and the external electrode  21  is expressed as d 6   a ×(5−n)/4≤D(n)≤d 6 a. In order to satisfy this relationship, in a case of a distance D(2) between the conductor pattern in the second turn as counted from the external electrode  22  and the external electrode  21 , since n=2, an inequality d 6   a ×¾≤D(2)≤d 6   a  is established. In a case where the distance D(2) between the conductor pattern in the second turn and the external electrode  21  is equal to the spacing d 4   a  between the conductor pattern C 14  and the external electrode  21 , an inequality d 6   a ×¾≤d 4   a ≤d 6   a  is established. Similarly, in a case of a distance D(3) between the conductor pattern in the third turn as counted from the external electrode  22  and the external electrode  21 , since n=3, an inequality d 6   a ×½≤D(3)≤d 6   a  is established. In a case where the distance D(3) between the conductor pattern in the third turn and the external electrode  21  is equal to the spacing d 2   a  between the conductor pattern C 12  and the external electrode  21 , an inequality d 6   a ×½≤d 2   a ≤d 1  is established. Similarly, in a case of a distance D(4) between the conductor pattern in the fourth turn as counted from the external electrode  22  and the external electrode  21 , since n=4, an inequality d 6   a ×¼≤D(4)≤d 6   a  is established. In a case where the distance D(4) between the conductor pattern in the fourth turn and the external electrode  21  is equal to the spacing d 1   a  between the conductor pattern C 11  and the external electrode  21 , an inequality d 6   a ×¼≤d 1   a ≤d 6   a  is established. It is also required to satisfy the condition that when n has a certain value, D(n) and D(1) have different values from each other, and thus D(1) (=d 6   a ) has a value different from at least one of respective values of D(2), D(3), and D(4). 
     According to the above-described embodiment, since the relationship D(1)×(N m+1)/N≤D(n)≤D(1) (where when n has a certain value, D(n) and D(1) have different values from each other) is satisfied, the conductor pattern (b1) having the largest potential difference from the external electrode  21  is arranged farthest from the external electrode  21 . As thus described, the distance between the conductor pattern (b1) having a large potential difference from the external electrode  21  and the external electrode  21  is set to be large, and thus an insulation property between the conductor pattern (b1) and the external electrode  21  is ensured. Even though a distance between the conductor pattern (bn) other than the conductor pattern (b1) and the external electrode  21  is equal to or less than a value of D(1), an insulation property between the conductor pattern (bn) and the external electrode  21  can be ensured. 
     In one embodiment of the present invention, the coil conductor  25  is configured so that the distance d(m) between the conductor pattern (am) in the m-th turn as counted from the external electrode  21  and the external electrode  22  is equal to or more than a distance d(m+1) between the conductor pattern (a(m+1)) in an (m+1)-th turn as counted from the external electrode  21  and the external electrode  22  (where when N is a maximum number of turns, m is any integer satisfying 1≤m≤N−1), and when m has a certain value, d(m) and d(m+1) have different values from each other. 
     In one embodiment of the present invention, the coil conductor  25  is configured so that the distance D(n) between the conductor pattern (bn) in the n-th turn as counted from the external electrode  22  and the external electrode  21  is equal to or more than a distance D(n+1) between the conductor pattern (b(n+1)) in an (n+1)-th turn as counted from the external electrode  22  and the external electrode  21  (where n is any integer satisfying 1≤n≤N−1), and when n has a certain value, D(n) and D(n+1) have different values from each other. 
     In the embodiment shown, the spacing d 1   c  between the conductor pattern (a1) in the first turn as counted from the external electrode  21  and the external electrode  22  is larger than the spacing d 3   c  between the conductor pattern (a2) in the second turn as counted from the external electrode  21  and the external electrode  22 . Furthermore, the spacing d 3   c  is larger than the spacing d 5   c  between a conductor pattern (a3) in the third turn as counted from the external electrode  21  and the external electrode  22 . Furthermore, the spacing d 5   c  is larger than the spacing d 6   c  between a conductor pattern (a4) in the fourth turn as counted from the external electrode  21  and the external electrode  22 . As thus described, in the embodiment shown, a relationship d 6   c &lt;d 5   c &lt;d 3   c &lt;d 1   c  is established. A magnitude relationship among the spacings between the conductor pattern in the m-th turn as counted from the external electrode  21  and the external electrode  22  is not limited to the relationship d 6   c &lt;d 5   c &lt;d 3   c &lt;d 1   c . Any two or three values selected from among respective values of the spacings d 1   c, d   3   c, d   5   c , and d 6   c  may be equal to each other. For example, in a case where the respective values of the spacings d 3   c  and  d   5   c , which are two values among the respective values of the spacings, are equal to each other, the magnitude relationship between the spacings is expressed as d 6   c &lt;d 5   c =d 3   c &lt;d 1   c . In a case where the respective values of the spacings d 1   c  and d 3   c , which are two values among the respective values of the spacings, are equal to each other, the magnitude relationship between the spacings is expressed as d 6   c &lt;d 5   c &lt;d 3   c =d 1   c . In a case where the respective values of the spacings d 3   c, d   5   c , and d 6   c , which are three values among the respective values of the spacings, are equal to each other, the magnitude relationship between the spacings is expressed as d 6   c =d 5   c =d 3   c &lt;d 1   c . The magnitude relationship among the spacings based on any other combination of equal spacings can be considered in a similar manner. 
     A similar relationship applies to a case where the number of turns is counted from the external electrode  22 . Specifically, in the embodiment shown, the spacing d 6   a  between the conductor pattern (b1) in the first turn as counted from the external electrode  22  and the external electrode  21  is larger than the spacing d 4   a  between a conductor pattern (b2) in the second turn as counted from the external electrode  22  and the external electrode  21 . Furthermore, the spacing d 4   a  is larger than the spacing d 2   a  between a conductor pattern (b3) in the third turn as counted from the external electrode  22  and the external electrode  21 . Furthermore, the spacing d 2   a  is larger than the spacing d 1   a  between a conductor pattern (b4) in the fourth turn as counted from the external electrode  22  and the external electrode  21 . As thus described, in the embodiment shown, a relationship d 1   a &lt;d 2   a &lt;d 4   a &lt;d 6   a  is established. Any two or three values selected from among respective values of the spacings d 1   a , d 2   a, d   4   a , and d 6   a  may be equal to each other. For example, in a case where the respective values of d 2   a  and  d   4   a , which are two values among the respective values of the spacings, are equal to each other, the magnitude relationship between the spacings is expressed as d 1   a &lt;d 2   a =d 4   a &lt;d 6   a . In a case where the respective values of d 6   a  and  d   4   a , which are two values among the respective values of the spacings, are equal to each other, the magnitude relationship between the spacings is expressed as d 1   a &lt;d 2   a &lt;d 4   a =d 6   a . In a case where the respective values of d 1   a , d 2   a , and d 4   a , which are three values among the respective values of the spacings, are equal to each other, the magnitude relationship between the spacings is expressed as d 1   a =d 2   a =d 4   a &lt;d 6   a . The magnitude relationship among the spacings based on any other combination of equal spacings can be considered in a similar manner. 
     According to the above-described embodiment, a relationship is satisfied in which the distance d(1) (d 1   c  in the embodiment shown) between the conductor pattern (a1) in the first turn as counted from the external electrode  21  and the external electrode  22  is larger than any of values of the distance d(m) between the conductor pattern (am) in the m-th turn as counted from the external electrode  21  and the external electrode  22 , and thus the conductor pattern (a1) having the largest potential difference from the external electrode  22  is arranged farthest from the external electrode  22 . As thus described, the distance between the conductor pattern (a1) having a large potential difference from the external electrode  22  and the external electrode  22  is set to be large, and thus an insulation property between the conductor pattern (a1) and the external electrode  22  is ensured. In the coil conductor  25 , a potential difference between the conductor pattern (am) other than the conductor pattern (a1) and the external electrode  22  is smaller than a potential difference between the conductor pattern (a1) and the external electrode  22 , and thus even though the distance d(m) is equal to or less than a value of d(1), an insulation property between the conductor pattern (a1) and the external electrode  22  can be ensured. 
     Similarly, a relationship is satisfied in which the distance D(1) (d 6   a  in the embodiment shown) between the conductor pattern (b1) in the first turn as counted from the external electrode  22  and the external electrode  21  is larger than any of values of the distance D(n) between the conductor pattern (bn) in the n-th turn as counted from the external electrode  22  and the external electrode  21 , and thus the conductor pattern (b1) having the largest potential difference from the external electrode  21  is arranged farthest from the external electrode  21 . As thus described, the distance between the conductor pattern (b1) having a large potential difference from the external electrode  21  and the external electrode  21  is set to be large, and thus an insulation property between the conductor pattern (b1) and the external electrode  21  is ensured. In the coil conductor  25 , a potential difference between the conductor pattern (bn) other than the conductor pattern (b1) and the external electrode  21  is smaller than a potential difference between the conductor pattern (b1) and the external electrode  21 , and thus even though the distance D(n) is equal to or less than a value of D(1), an insulation property between the conductor pattern (b1) and the external electrode  21  can be ensured. 
     As mentioned above, in the embodiment shown, when viewed from the direction of the coil axis A, an inner periphery of each of the conductor patterns C 11  to C 16  extends along at least part of the closed loop B. Thus, as shown in  FIG.  4   , a plane C extending through the respective inner peripheral surfaces C 11   g  to C 16   g  of the conductor patterns C 11  to C 16  extends parallel to the coil axis A. Therefore, a magnetic flux passing through a core defined by the respective inner peripheral surfaces dig to C 16   g  of the conductor patterns C 11  to C 16  is directed parallel to the coil axis A. This can prevent a degradation in inductance due to a direction of a magnetic flux passing through the core being inclined with respect to the coil axis A. 
     As shown in  FIG.  3   a   , on the closed loop B, there are a first position P 1  closest to the first external electrode  21  and a second position P 2  closest to the second external electrode  22 . In the embodiment shown, an outline of the insulating layer  11  and the closed loop B both have a rectangular shape, and thus the first position P 1  is any position on the side Ba of the closed loop B, and the second position P 2  is any position on the side Bc of the closed loop B. Arrangements of the first position P 1  and the second position P 2  are set as appropriate depending on a shape of the laminate  10  and a shape of the closed loop B. 
       FIG.  5   a    is a sectional view of the conductor pattern C 11  cut in a direction perpendicular to an extending direction of the conductor pattern C 11  so as to extend through the first position P 1 . Specifically,  FIG.  5   a    is a sectional view of the first portion C 11   a  of the conductor pattern C 11  along a line II-II in  FIG.  3   a   .  FIG.  5   b    is a sectional view of the conductor pattern C 11  cut in the direction perpendicular to the extending direction of the conductor pattern C 11  so as to extend through the second position P 2 . Specifically,  FIG.  5   b    is a sectional view of the third portion C 11   c  of the conductor pattern C 11  along a line III-Ill in  FIG.  3     a.    
     As described above, the coil conductor  25  is formed so that the distance between the conductor pattern (a1) in the first turn as counted from the external electrode  21  and the external electrode  22  is larger than a distance between each of the other conductor patterns (the conductor pattern (am)) and the external electrode  22 . Such a relationship is achieved by, for example, a technique in which, at the second position P 2 , with an inner periphery of the conductor pattern (a1) secured on the closed loop B, the dimension W 1   c  of the conductor pattern (a1) in a width direction is reduced. In this case, at the second position P 2 , a direct current resistance (Rdc) of the conductor pattern C 11  is disadvantageously increased. As a solution to this, the conductor pattern C 11  is formed so that a thickness thereof at the second position P 2  is greater than that at any other portion thereof, and thus it is possible to prevent an increase in direct current resistance (Rdc) of the conductor pattern C 11  at the second position P 2 . For example, the conductor pattern C 11  could be formed so that a cross-sectional area thereof at the second position P 2  is equal to that at the first position P 1 . Based on dimensions shown in  FIG.  5   a   , the cross-sectional area of the conductor pattern C 11  at the first position P 1  is a product of W 1   a  and H 1   a , and based on dimensions shown in  FIG.  5   b   , the cross-sectional area of the conductor pattern C 11  at the second position P 2  is a product of W 1   c  and H 1   c . The conductor pattern C 11  is formed so that the product of W 1   a  and H 1   a  is equal to the product of W 1   c  and H 1   c . Similarly, the conductor pattern C 16  may be formed so that a cross-sectional area thereof at the second position P 2  is equal to that at the first position P 1 . 
     Next, a description is given of an example of a production method of the coil component  1 . First, magnetic sheets used to form the insulating layers  11  to  16 , the insulating layers  18   a  to  18   d , and the insulating layers  19   a  to  19   d  are prepared. Specifically, a solvent is added to a resin material to produce slurry. The resin material is, for example, a resin (a resin having an excellent insulation property such as, for example, a polyvinyl butyral (PVB) resin or an epoxy resin) in which filler particles are dispersed. The slurry is applied to a surface of a base film made of plastic and then dried, and the dried slurry is cut to a predetermined size. The magnetic sheets are obtained in this manner. 
     Next, at predetermined positions on the magnetic sheets used to form the insulating layers  11  to  15 , through-holes are formed so as to extend through these insulating layers in the T axis direction, respectively. 
     Next, by printing such as screen printing, plating, etching, or any other known method, on an upper surface of the magnetic sheet used to form the insulating layer  11 , a multitude of conductor patterns corresponding to the conductor pattern C 11  and the lead-out conductor  23  are formed from a metal material (for example, Ag), and the metal material is filled into the through hole formed through this magnetic sheet. Similarly, on upper surfaces of the magnetic sheets used to form the insulating layers  12  to  14 , a multitude of conductor patterns corresponding to the conductor patterns C 12  to C 15  are formed, respectively, and the metal material is filled into the through holes formed through these magnetic sheets. Furthermore, on an upper surface of the magnetic sheet used to form the insulating layer  16 , a multitude of conductor patterns corresponding to the conductor pattern C 16  and the lead-out conductor  24  are formed from a metal material (for example, Ag). A metal thus filled into the through-holes forms the vias V 1  to V 5 . 
     Next, the magnetic sheets with the conductor patterns corresponding to the conductor patterns C 11  to C 16  formed thereon are stacked together to obtain an intermediate laminate. These magnetic sheets are stacked together so that the conductor patterns C 11  to C 16  formed thereon, respectively, are each electrically connected to an adjacent one of the conductor patterns via the vias V 1  to V 5 . 
     Next, the magnetic sheets used to form the insulating layers  18   a  to  18   d  are stacked together to from a top laminate corresponding to the top cover layer  18 , and the magnetic sheets used to form the insulating layers  19   a  to  19   d  are stacked together to form a bottom laminate corresponding to the bottom cover layer  19 . 
     Next, the intermediate laminate formed in the above-described manner is sandwiched from top and bottom between the top laminate and the bottom laminate, and the top laminate and the bottom laminate are bonded to the intermediate laminate by thermal compression to obtain a body laminate. Next, the body laminate is segmented into units of a desired size by using a cutter such as a dicing machine or a laser processing machine to obtain a chip laminate corresponding to the laminate  10 . Next, the chip laminate is subjected to degreasing, and the chip laminate thus degreased is heat-treated. Next, a conductor paste is applied to both end portions of the heat-treated chip laminate to form the external electrode  21  and the external electrode  22 . Thus, the coil component  1  is obtained. 
     The dimensions, materials, and arrangements of the various constituent elements described in this specification are not limited to those explicitly described in the embodiments, and the various constituent elements can be modified to have any dimensions, materials, and arrangements within the scope of the present invention. Furthermore, constituent elements not explicitly described in this specification can also be added to the embodiments described, and some of the constituent elements described in the embodiments can also be omitted.