Abstract:
A printed board, includes: a first shield portion, configured to reduce an influence of an electric field in combination with a casing accommodating the printed board, at least a part of the first shield portion being formed with a plurality of through holes; and a second shield portion, configured to reduce the influence of the electric field in combination with the casing, at least a part of the second shield portion being formed with a plurality of through holes, wherein the second shield portion is arranged alongside of the first shield portion.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates to a printed board having a shield portion, and in particular, to a current/voltage detection printed board that is used to detect an alternating current (AC) voltage generated at a power transmission conductor used as an alternating current power transmission path and an alternating current flowing in the power transmission conductor, and to a current/voltage detector using the current/voltage detection printed board. 
     2. Description of the Related Art 
     Like an impedance matching device or a high-frequency power supply device, there is known a device that detects AC power current and voltage and performs a control using the detected current and voltage. As an example, an impedance matching device will now be described. 
       FIG. 35  is a block diagram of an example of a high-frequency power supply system that uses an impedance matching device. 
     The high-frequency power supply system is a system that performs a processing, such as plasma etching or plasma CVD, on a workpiece, such as a semiconductor wafer or a liquid crystal substrate. The high-frequency power supply system includes a high-frequency power supply device  61 , a transmission line  62 , an impedance matching device  63 , a load connection portion  64 , and a load  65  (plasma processing device  65 ). 
     The high-frequency power supply device  61  is a device that outputs high-frequency power to the plasma processing device  65  as a load. Moreover, high-frequency power output from the high-frequency power supply device  61  is supplied to the plasma processing device  65  through the transmission line  62  having a coaxial cable, the impedance matching device  63 , and the load connection portion  64  having a shielded copper plate. In general, the high-frequency power supply device  61  outputs high-frequency power having a frequency of a radio frequency band (for example, a frequency of hundreds kHz or more, and just about less than 1 GHz although not strictly-set the upper limit). 
     The plasma processing device  65  is a device that performs a processing (etching or CVD) on a wafer or a liquid crystal substrate. 
     The impedance matching device  63  includes a matching circuit that has a variable impedance element (for example, a variable capacitor, a variable inductor, or the like) (not shown) therein. The impedance matching device  63  has a control function of changing impedance of the variable impedance element in the matching circuit to accomplish impedance matching between the high-frequency power supply device  61  and the load  65 . 
     In order to perform the above-described control, a current detector and a voltage detector are provided between an input terminal  63   a  of the impedance matching device  63  and the matching circuit. The current detector and the voltage detector detect high-frequency current and high-frequency voltage output from the high-frequency power supply device  61 . Information of forward wave power or reflected wave power is obtained using the current and voltage detected by the detectors. Then, impedance of the variable impedance element is controlled using the obtained information to accomplish impedance matching. 
       FIG. 36  is a schematic circuit diagram of a current detector  80  and a voltage detector  90  provided between the input terminal and a matching circuit  67  of the impedance matching device  63 . As shown in  FIG. 36 , a power transmission conductor  66  (for example, rod-shaped copper) serving as a power transmission path is provided between the input terminal  63   a  and the matching circuit  67 . Then, the current detector  80  and the voltage detector  90  are provided on the power transmission conductor  66 . 
     The current detector  80  has a current transformer  81 , output wires  82  and  83  of the current transformer  81 , a current conversion circuit  84 , and an output wire  85  of the current conversion circuit  84 . In the current detector  80 , a current according to an AC current that flows in the power transmission conductor  66  flows in the current transformer  81 . This current is input to the current conversion circuit  84  through the output wires  82  and  83  and is converted into a predetermined voltage level. Then, the converted voltage is output from the output wire  85  of the current conversion circuit  84 . 
     The voltage detector  90  has a capacitor  91 , an output wire  92  of the capacitor  91 , a voltage conversion circuit  93 , and an output wire  94  of the voltage conversion circuit  93 . In the voltage detector  90 , a voltage according to an AC voltage generated in the power transmission conductor  66  is generated in the capacitor  91 . This voltage is input to the voltage conversion circuit  93  through the output wire  92  and is converted into a predetermined voltage level. Then, the converted voltage is output from the output wire  94  of the voltage conversion circuit  93 . 
     Subsequently, as described above, the information of forward wave power or reflected wave power is obtained using the current and voltage detected by the current detector  80  and the voltage detector  90 . The current detector  80  and the voltage detector  90  have a structure shown in  FIGS. 28 and 29 . 
       FIG. 37  is a schematic exterior view of the current detector  80  and the voltage detector  90 . 
       FIGS. 38A to 38C  are explanatory views illustrating the configuration of the current detector  80  and the voltage detector  90  shown in  FIG. 37 . Specifically,  FIG. 38A  is a diagram showing the interior of a casing (indicated by a dotted line) of  FIG. 27  in perspective view.  FIG. 38B  is a diagram showing the vicinity of the current transformer  81  as viewed from the transverse side of  FIG. 38A .  FIG. 38C  is a diagram showing the vicinity of the capacitor  91  as viewed from the transverse side of  FIG. 38A . 
     In  FIGS. 37 and 38A  to  38 C, the power transmission conductor  66  and an insulator  69  covering the power transmission conductor  66 , not included in the current detector  80  and the voltage detector  90 , are shown for explanation. Further, in  FIGS. 37 and 38A  to  38 C, for convenience, the same parts as those in  FIG. 36  are represented by the same reference numerals. 
     Hereinafter, the current detector  80  and the voltage detector  90  will be described with reference to  FIGS. 37 and 38A  to  38 C. 
     In  FIGS. 37 and 38A  to  38 C, the power transmission conductor  66  is, for example, a cylindrical copper rod. The periphery of the power transmission conductor  66  is covered with a hollow insulator  69 . Then, the power transmission conductor  66  and the insulator  69  pass through a casing  71 . Further, the current transformer  81  constituting the current detector  80  and the capacitor  91  constituting the voltage detector  90  are accommodated in the casing  71 . 
     In the current transformer  81 , a coated copper wire or the like is wound around a ring-shaped magnetic core (for example, a toroidal core made of ferrite) to form a coiled wire. Then, the current transformer  81  is disposed such that the power transmission conductor  66  passes through the magnetic core. Accordingly, a current according to a current flowing in the power transmission conductor  66  flows in the coiled wire of the current transformer  81 . 
     The current flowing in the current transformer  81  is input to the current conversion circuit  84  through the output wires  82  and  83  that are connected to both ends of the coiled wire. Then, the current conversion circuit  84  converts the input current into a predetermined voltage level and outputs the converted voltage. 
     The capacitor  91  is formed by providing a ring-shaped conductor  91   b  (for example, a copper ring) in the vicinity of the insulator  69 . The ring-shaped conductor  91   b  and a portion  91   a  facing the power transmission conductor  66  function as electrodes of the capacitor. Accordingly, a voltage according to the voltage generated in the power transmission conductor  66  is generated in the capacitor  91 . The voltage generated in the capacitor  91  is input to the voltage conversion circuit  93  through the output wire  92  connected to the ring-shaped conductor  91   b . Then, the voltage conversion circuit  93  converts the input voltage into a predetermined voltage level and outputs the converted voltage. 
     Moreover, in  FIGS. 37 and 38A  to  38 C, the output wire  85  of the current conversion circuit  84  and the output wire  94  of the voltage conversion circuit  93  are not shown. Further, in order to protect the current conversion circuit  84  and the voltage conversion circuit  93  from an influence of an electromagnetic wave, a common conductor cover  72  is provided to cover the current conversion circuit  84  and the voltage conversion circuit  93 .  FIG. 37  shows a state where the cover  72  is removed, in order to show the current conversion circuit  84  and the voltage conversion circuit  93 . Further, in  FIGS. 38A to 38C , the cover  72  is not shown. 
     As described with reference to  FIGS. 37 and 38A  to  38 C, the current detector  80  and the voltage detector  90  have the casing that covers the current transformer  81 , the capacitor  91 , and the like, in addition to the parts of the circuit diagram in  FIG. 38 . The casing is common to the current detector  80  and the voltage detector  90  according to the related art. 
     The current detector  80  and the voltage detector  90  described above can be used to other devices, such as the high-frequency power supply device  61  or the like. For example, in case of the high-frequency power supply device, the current detector and the voltage detector are provided at an output terminal of the high-frequency power supply device  61 . In this case, the current detector and the voltage detector are used to detect current and voltage required for controlling output forward wave power to have a set value. 
     The current detector and the voltage detector may detect current and voltage at the output terminal  63   b  of the impedance matching device or the input terminal of the load  65  and may be used to control or analyze the detected current or voltage. 
       FIG. 39  is a circuit diagram showing a case where the current detector  80  and the voltage detector  90  are provided between the matching circuit and the output terminal in the impedance matching device. 
     As shown in  FIG. 39 , the current detector  80  and the voltage detector  90  are provided on the power transmission conductor  68  between the matching circuit  67  and the output terminal  63   b  in the impedance matching device  63 . In this case, the current detector  80  and the voltage detector  90  detect current and voltage at the output terminal  63   b  of the impedance matching device  63 . 
     In  FIG. 39 , the same parts as those of the circuit diagram in  FIG. 36  are represented by the same reference numerals. Meanwhile, there is a difference in current and voltage at the input terminal  63   a  and the output terminal  63   b  of the impedance matching device  63 . Accordingly, the current detector  80  and the voltage detector  90  have a structural difference in view of current resistance and voltage resistance. In  FIG. 39 , the same reference numerals are used regardless of the structural difference. For example, the output terminal  63   b  of the impedance matching device  63  has higher current and voltage than the input terminal  63   a  thereof. For this reason, when the current detector  80  and the voltage detector  90  are provided at the output terminal  63   b  of the impedance matching device  63 , it is necessary to extend an insulation length, compared with a case where the current detector  80  and the voltage detector  90  are provided at the input terminal  63   a  of the impedance matching device  63 . In order to extend the insulation length, a conductor having a large diameter is used as the power transmission conductor  68  or the insulator  69  covering the periphery of the power transmission conductor  68  has a large thickness. In  FIG. 39 , however, for convenience, the structural difference is not considered. 
     As shown in  FIG. 39 , when the current detector and the voltage detector are used in the impedance matching device  63 , it is necessary to additionally provide a detector for detecting information of current and voltage for impedance matching on the input side of the impedance matching device  63 . 
     Besides, the above examples are disclosed by, for example, JP-A-2003-302431 and JP-A-2004-85446. 
     Since the current transformer  81  constituting the current detector  80  is formed by winding the wire around the magnetic core, a variation in wiring interval or wiring strength may easily occur. For this reason, when a plurality of current detectors  80  are formed, a variation in detection value of the individual current detectors  80  may easily occur. 
     Further, a variation in shape of the output wires  82  and  83  of the current transformer  81  may easily occur, which may cause a variation in current detection value. 
     The inner diameter of the ring-shaped conductor  91   b  constituting the voltage detector  90  is substantially consistent with the outer diameter of the insulator  69  covering the periphery of the power transmission conductor  66 . The ring-shaped conductor  91   b  is fitted into the insulator  69 . That is, the ring-shaped conductor  91   b  is positioned by the insulator  69 . However, the insulator  69  may be thinned due to a secular change or the like. In this case, the position of the ring-shaped conductor  91   b  may be unstable, and a gap may occur between the power transmission conductor  66  and the insulator  69 . In this state, if an external force acts on the power transmission conductor  66 , the positional relationship between the power transmission conductor  66  and the ring-shaped conductor  91   b  changes. Then, a voltage detection value changes from an initial state (upon adjustment of the detector). Besides, since the position of the ring-shaped conductor  91   b  is unstable, when a plurality of voltage detectors  90  are formed, a variation in detection value of the individual voltage detectors  90  may easily occur. 
     Further, a variation in shape of the output wire  92  of the ring-shaped conductor  91   b  may easily occur, which may cause a variation in voltage detection value. 
     That is, in case of the current detector  80  or the voltage detector  90 , when a plurality of detectors are formed, a variation in detection value of the individual detectors may easily occur. 
     Further, since the wire is wound around the core in the current transformer  81  constituting the current detector  80 , there is a self-resonant frequency by self inductance and line capacitance. However, since relative magnetic permeability of a magnetic material used for the core is large, the self-resonant frequency becomes low. For this reason, an upper limit of a detectable frequency band becomes low. That is, the detectable frequency band is limited. 
     The current detection point and the voltage detection point are preferably the same, but as shown in  FIGS. 38A to 38C , the current detection point and the voltage detection point may be away from each other in the axial direction of the power transmission conductor  66 . 
     SUMMARY OF THE INVENTION 
     The invention has been finalized in consideration of the above problems, and an object of the invention is to provide a current/voltage detection printed board that can approximate a current detection point and a voltage detection point, and a current/voltage detector using the printed board. Another object of the invention is to provide a current/voltage detector that can reduce a variation in a detection value, even if a plurality of detectors are formed. 
     According to a first aspect of the invention, there is provided a printed board, including: a first shield portion, configured to reduce an influence of an electric field in combination with a casing accommodating the printed board, at least a part of the first shield portion being formed with a plurality of through holes; and a second shield portion, configured to reduce the influence of the electric field in combination with the casing, at least a part of the second shield portion being formed with a plurality of through holes, wherein the second shield portion is arranged alongside of the first shield portion. 
     According to a second aspect of the invention, each of the first shield portion and the second shield portion includes an unshielded portion. 
     According to a third aspect of the invention, no unshielded portion is provided with respect to the first shield portion and the second shield portion. 
     According to a fourth aspect of the invention, a printed board, configured to detect an AC current flowing in a power transmission conductor and an AC voltage generated in the power transmission conductor, the power transmission conductor being used as an AC power transmission path, the printed board including: a first wire, configured to detect the AC voltage; a shield portion, configured to reduce an influence of an electric field of the AC current in combination with a casing accommodating the printed board, at least a part of the shield portion being formed with a plurality of through holes; and a second wire, configured to detect the AC current, wherein: the printed board is formed with a penetration hole; the first wire is provided between the penetration hole and the shield portion; and the shield portion is provided between the first wire and the second wire. 
     According to a fifth aspect of the invention, the through holes are arranged in a substantially circular shape. 
     According to a sixth aspect of the invention, the through holes are arranged in a substantially circular shape and in at least two lines. 
     According to a seventh aspect of the invention, there is provided a detector, configured to detect an AC current flowing in a power transmission conductor and an AC voltage generated in the power transmission conductor, the power transmission conductor being used as an AC power transmission path, the detector including: a casing; and a printed board including: a first wire, configured to detect the AC voltage; a shield portion, configured to reduce an influence of an electric field of the AC current in combination with the casing accommodating the printed board, at least a part of the shield portion being formed with a plurality of through holes; and a second wire, configured to detect the AC current, wherein: the printed board is formed with a penetration hole; the first wire is provided between the penetration hole and the shield portion; the shield portion is provided between the first wire and the second wire; and the casing covers the printed board excluding the penetration hole. 
     According to an eighth aspect of the invention, the through holes are arranged in a substantially circular shape. 
     According to a ninth aspect of the invention, the through holes are arranged in a substantially circular shape and in at least two lines. 
     According to a tenth aspect of the invention, the shield portion includes an unshielded portion where the influence of the electric field is not reduced. 
     According to an eleventh aspect of the invention, the unshielded portion is provided between a first surface and a second surface of the printed board. 
     According to a twelfth aspect of the invention, the unshielded portion is provided between the printed board and the casing. 
     According to a thirteenth aspect of the invention, the casing includes: a main body, configured to fix the print board; and a cover portion, configured to accommodate the print board. 
     According to a fourteenth aspect of the invention, the print board includes a plurality of layers laminated each other; the first wire is formed with a plurality of through holes arranged along the periphery of the penetration hole, the through holes penetrating between a part of the layers; and the first wire includes a pattern wire connecting the through holes. 
     According to a fifteenth aspect of the invention, the AC current has a frequency of a radio frequency band. 
     The second wire may include at least one wire that is formed in a coiled shape having both ends by penetrating between a top conductive layer and a bottom conductive layer of the board and alternately connecting the top conductive layer and the bottom conductive layer of the board or/and at least one wire that is formed in a coiled shape having both ends by penetrating a part of layers of the board and alternately connecting the top conductive layer and the bottom conductive layer of the penetrating portion. 
     The second wire may include through holes formed at the penetrating portion penetrating between the top conductive layer and the bottom conductive layer of the board or the part of layers of the board, and pattern wires formed on the top conductive layer and the bottom conductive layer of the penetrating portion. 
     When a plurality of second wires are formed in the board, both ends or electrically identical portions of each second wire may be electrically connectable to both ends or electrically identical portions of another second wire. 
     The penetration hole may have a circular shape, the first wire may be substantially formed in a circular shape along the periphery of the penetration hole, and the second wire may be substantially formed in a circular shape. 
     The through holes can be easily formed in manufacturing the printed board. Therefore, according to the aspects of the invention, the shield portion can be easily formed in the printed board. 
     Like the fourth aspect of the invention, since a voltage detection portion and a current detection portion are provided in the same board, the voltage detection point and the current detection point can be substantially the same. 
     Like the fourth and seventh aspects of the invention, when the shield portion formed by the through holes is used, even if the voltage detection portion and the current detection portion are provided in the same board, an influence of an electric field on the current detection portion can be reduced, and a magnetic flux required for current detection can act on the current detection portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiment may be described in detail with reference t o the accompanying drawings, in which: 
         FIGS. 1A to 1D  are diagrams showing an example of a current detection printed board  1  according to the invention; 
         FIG. 2  is a diagram showing a case where a power transmission conductor  66 , in which an AC current flows, and an insulator  69  covering the power transmission conductor  66  are disposed to pass through a penetration hole  101  provided in the current detection printed board  1 ; 
         FIGS. 3A to 3E  are diagrams showing another example of the current detection printed board  1  according to the invention; 
         FIGS. 4A and 4B  are diagrams showing another example of a coiled wire  10 ; 
         FIG. 5  is a diagram showing another example of the current detection printed board  1  according to the invention; 
         FIG. 6  is a connection diagram of the current detection printed board  1  shown in  FIG. 5 ; 
         FIG. 7  is a diagram showing another example of the current detection printed board  1  according to the invention; 
         FIGS. 8A to 8E  are diagrams the arrangement examples of a first coiled wire  10 - 1  and a second coiled wire  10 - 2 ; 
         FIGS. 9A to 9D  are diagram showing an example of a voltage detection printed board  2  according to the invention; 
         FIGS. 10A to 10E  are diagrams showing another example of the voltage detection printed board  2  according to the invention; 
         FIGS. 11A and 11B  show another example of a ring-shaped wire  30 ; 
         FIGS. 12A to 12C  are schematic exterior views of a current/voltage detector  3   a  according to the invention; 
         FIGS. 13A and 13B  are diagrams showing the schematic configuration of the current/voltage detector  3   a  shown in  FIGS. 12A to 12C ; 
         FIG. 14  is a cross-sectional view of the current/voltage detector  3   a  shown in  FIG. 12B ; 
         FIGS. 15A to 15E  are diagrams showing an example of a current/voltage detection printed board  4  according to the invention; 
         FIGS. 16A to 16E  are diagrams showing another example of the current/voltage detection printed board  4  according to the invention; 
         FIGS. 17A and 17B  are diagrams showing an example of an output wire  40  that is connected to a ring-shaped wire  30 ; 
         FIGS. 18A and 18B  are diagrams showing another example of the output wire  40  that is connected to the ring-shaped wire  30 ; 
         FIGS. 19A and 19B  are diagrams showing another example of the output wire  40  that is connected to the ring-shaped wire  30 ; 
         FIGS. 20A and 20B  are diagrams showing another example of the output wire  40  that is connected to the ring-shaped wire  30 ; 
         FIG. 21  is a schematic exterior view three-dimensionally showing a current/voltage detector  3   b  according to the invention; 
         FIG. 22  is a diagram showing the schematic configuration of the current/voltage detector  3   b  shown in  FIG. 21 ; 
         FIGS. 23A and 23B  are diagrams of a casing main body  300 ; 
         FIG. 24  is a diagram three-dimensionally showing the casing main body  300 ; 
         FIG. 25  is a diagram when the current/voltage detection printed board  4  is mounted on the casing main body  300  in a state where the cover  301  is not mounted; 
         FIG. 26  is a diagram three-dimensionally showing the casing main body  300  when no board fixing portion  315  is provided; 
         FIGS. 27A and 27B  show an example of an application of a third casing shield portion  308 ; 
         FIG. 28  show an example of a cross-sectional view when the current/voltage detection printed board  4  is accommodated in the casing; 
         FIGS. 29A and 29B  show another example of cross-sectional views when the current/voltage detection printed board  4  is accommodated in the casing; 
         FIGS. 30A and 30B  show another example of cross-sectional views when the current/voltage detection printed board  4  is accommodated in the casing; 
         FIG. 31  is a diagram showing a current/voltage detector  3   c  as a modification of the current/voltage detector  3   b;    
         FIG. 32  is a diagram showing a current/voltage detector  3   d  as a modification of the current/voltage detector  3   b;    
         FIG. 33  is a diagram showing a fixing method of the insulator  69 ; 
         FIG. 34  is a diagram showing a case where the sizes of the power transmission conductor  66  and the insulator  69  in the current/voltage detector  3   b  of  FIG. 33  are suited to the size of the current/voltage detector  3   b;    
         FIG. 35  is a block diagram of an example of a high-frequency power supply system that uses an impedance matching device; 
         FIG. 36  is a schematic circuit diagram of a current detector  80  and a voltage detector  90  provided between an input terminal and a matching circuit  67  of an impedance matching device  63 ; 
         FIG. 37  is a schematic exterior view of the current detector  80  and the voltage detector  90 ; 
         FIGS. 38A to 38C  are explanatory views illustrating the configuration of the current detector  80  and the voltage detector  90  shown in  FIG. 37 ; and 
         FIG. 39  is a circuit diagram showing a case where the current detector  80  and the voltage detector  90  are provided between the matching circuit and the output terminal in the impedance matching device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, the details of the invention will be described with reference to the drawings. 
     (1) Current Detection Printed Board 
       FIGS. 1A to 1D  are diagrams showing an example of a current detection printed board  1  according to the invention. 
     Specifically,  FIG. 1A  is a plan view of the current detection printed board  1  (as viewed from the above)  FIG. 1B  is a schematic view of a portion (a portion A surrounded by a dotted line) of  FIG. 1A  on magnified scale.  FIG. 1C  is a diagram showing linear expansion for simplification of  FIG. 1B .  FIG. 1D  shows a wire of the current detection printed board  1  when  FIG. 1C  is viewed from the side. Moreover, as regards the wire shown in  FIG. 1D , portions that are not typically viewed are shown in perspective view for explanation. 
     As shown in  FIGS. 1A to 1D , the current detection printed board  1  is provided with a penetration hole  101  that penetrates a board. A wire  10  (hereinafter, referred to as a coiled wire  10 ) that is formed in a coiled shape is provided along the periphery of the penetration hole  101 . The coiled wire  10  is formed in a coiled shape having both ends by alternately connecting a front surface  121  and a rear surface  122  of the board while penetrating the board. Portions of the wire penetrating the board are formed by through holes  11  and wires of the front surface and the rear surface of the board are formed by pattern wires  12  and  13 . 
     Moreover, in  FIGS. 1B and 1C , portions indicated by dotted lines represent pattern wires of the rear surface of the board. These portions are in perspective view, and thus indicated by dotted lines. Output wires  21  and  22  are connected to both ends  10   a  and  10   b  of the coiled wire  10 . The output wires are connected to output terminals  23  and  24 . 
     In this example, the board having a double-sided structure (hereinafter, referred to a double-sided board) is used. Accordingly, the pattern wires are formed on a front surface layer and a rear surface layer of one insulator member  110 . 
     The coiled wire  10  is an example of a coiled first wire of the invention, and the output wires  21  and  22  are examples of the second wire of the invention. 
       FIG. 2  is a diagram showing a case where a power transmission conductor  66 , in which an AC current flows, and an insulator  69  covering the power transmission conductor  66  are disposed to pass through the penetration hole  101  provided in the current detection printed board  1 . Moreover, for simplification, the wire is not shown. Further, in this embodiment and the following embodiments, a case where the current detection printed board or a voltage detection printed board described below is provided between an input terminal and a matching circuit  67  of an impedance matching device  63 . 
     In case of the current detection printed board  1  shown in  FIG. 1 , as shown in  FIG. 2 , when the power transmission conductor  66 , in which an AC current flows, is disposed to pass through the penetration hole  101 , a current flows in the coiled wire  10  by electromagnetic induction. That is, the printed board can have a current transformer. Specifically, a current transformer can be formed in the current detection printed board  1 . 
     Accordingly, the portions of the coiled wire  10  correspond to the current transformer  81  in the circuit diagram shown in  FIG. 36 . 
     With this configuration, the portions of the coiled wire  10  are formed by the through holes and the pattern wires, and thus there is almost no variation in shape or position. Accordingly, there is almost no variation in winding interval or winding strength. Therefore, when a plurality of current detection printed boards  1  are formed, a variation in current detection value of the individual current detection printed boards  1  can be reduced. 
     In particular, if AC power to be transmitted through the power transmission conductor  66  is AC power having a frequency of a radio frequency band, a variation in winding interval or winding strength of the current detection printed board  1  may have a large effect on the current detection value. However, according to the current detection printed board  1  having the above configuration, even though AC power having a frequency of a radio frequency band is adopted, an influence thereof can be suppressed to the minimum. 
     As described below, a current conversion circuit  51  corresponding to the current conversion circuit  84  shown in  FIG. 36  may be provided on the current detection printed board  1  of  FIG. 1 . In this case, the output terminals  23  and  24  shown in  FIG. 1  are not required, and the output wires  21  and  22  of the coiled wire  10  are directly connected to the current conversion circuit  51 . 
     The insulator member  110  of the board is formed of, for example, glass epoxy. Relative magnetic permeability of the insulator member  110  of the board is smaller than a magnetic material. For this reason, a self-resonant frequency may be higher, compared with a case where a current transformer is formed by winding a wire around a magnetic material uses as a core, like the related art. Accordingly, an upper limit of a detectable frequency band is higher than the related art. 
       FIGS. 3A to 3E  are diagrams showing another example of the current detection printed board  1  according to the invention. 
     Specifically,  FIG. 3A  is a plan view of the current detection printed board  1 .  FIG. 3B  is a schematic view of a portion (a portion B surrounded by a dotted line) of  FIG. 3A  on magnified scale.  FIG. 3C  is a diagram showing linear expansion for simplification of  FIG. 3B .  FIG. 3D  shows a wire of the current detection printed board  1  when  FIG. 3C  is viewed from the side.  FIG. 3E  shows the wire of the current detection printed board  1  paying emphasis on the output wire  21  as viewed from the side. Moreover, as regards the wire shown in  FIGS. 3A to 3E , portions that are not typically viewed are shown in perspective view for explanation. In addition, for convenience, the current detection printed board  1 , through holes  11 , pattern wires  12  and  13 , and the like are represented by the same reference numerals as those in  FIGS. 1A to 1D . 
     The current detection printed board  1  shown in  FIGS. 3A to 3E  is specifically the same as the current detection printed board  1  shown in  FIGS. 1A to 1D , except that the board has a multilayer structure, and the coiled wire  10  is formed between inner layers. 
     Moreover, in this specification, insulator materials constituting the board having a multilayer structure (hereinafter, referred to as a multilayer board) are appropriately called a first insulator material, a second insulator material, a third insulator material, . . . in sequence from the upper portion of the drawings. Further, conductive layers to be formed between the individual insulator materials of the board are appropriately called a first conductive layer, a second conductive layer, a third conductive layer, . . . . Further, a conductive layer to be formed at the front surface of the board is called a front surface layer, and a conductive layer to be formed at the rear surface of the board is called a rear surface layer. 
     Moreover, although the double-sided board has the front surface layer and the rear surface layer and may be called a multilayer board, since only one insulator material exists, there are no conductive layers to be formed between the individual insulator materials of the board. 
     In the example of  FIGS. 3A to 3E , the insulator materials of the board include three insulator materials of a first insulator material  111 , a second insulator  112 , and a third insulator material  113 . Then, a first conductive layer  131  is formed between the first insulator material  111  and the second insulator material  112 , and a second conductive layer  132  is formed between the second insulator material  112  and the third insulator material  113 . Further, a front surface layer can be formed on a front surface  121  (a surface on the first insulator material) of the board. In addition, a rear surface layer can be formed on a rear surface  122  (a lower surface of the third insulator material) In the example of  FIGS. 3A to 3E , the rear surface layer of the board is not provided. 
     For this reason, in  FIGS. 3A to 3E , the coiled wire  10  is formed between the first conductive layer  131  and the second conductive layer  132 . Accordingly, the coiled wire  10  can have a structure that cannot be viewed from the outside of the board. In this case, portions of the coiled wire  10  correspond to the current transformer  81  of the circuit diagram shown in  FIG. 27 . 
     Further, as shown in  FIG. 3E , the output wire  21  of the coiled wire  10  is formed by a pattern wire  21   a  connected to one end  10   a  of the coiled wire  10  formed in the first conductive layer  131 , a through hole  21   b , and a pattern wire  21 C formed on the front surface of the board. The output wire  21  is connected to the output terminal  23 . The output wire  22  of the coiled wire  10  is the same as the output wire  21 , and thus the description thereof will be omitted. 
     Moreover, as described below, the current conversion circuit  51  corresponding to the current conversion circuit  84  shown in  FIG. 36  may be formed on the current detection printed board  1  of  FIGS. 3A to 3E . In this case, the output terminals  23  and  24  shown in  FIGS. 3A to 3E  are not required, and thus the output wires  21  and  22  of the coiled wire  10  are directly connected to the current conversion circuit  51 . 
       FIGS. 4A and 4B  are diagram showing another example of the coiled wire  10 . For example, as shown in  FIG. 4A , the coiled wire  10  may be formed between the front surface layer of the board and the second conductive layer  132 . Moreover, in  FIG. 4A , since the rear surface layer is not provided on the rear surface  122  of the board, the coiled wire  10  is formed by alternately connecting the front surface layer as a top conductive layer of the board and the second conductive layer  132  as a bottom conductive layer of the board. 
     Further, as shown in  FIG. 4B , the coiled wire  10  may be formed between the front surface layer as a top conductive layer and the rear surface layer as a bottom conductive layer of the board. Moreover, in  FIG. 4B , like  FIGS. 1A to 1D , the coiled wire  10  is formed by alternately connecting the front surface layer and the rear surface layer of the board. 
     In general, a through hole is one for connection between layers by forming a penetration hole between the layers of the board and providing a conductive layer (for example, copper) in the penetration hole. Moreover, the term ‘between the layers’ may mean ‘between all layers’ or ‘between some layers’. 
     The through hole is a type of inserting a lead line. However, the through hole only for connection between the layers is particularly called a via hole. Then, the via hole includes a penetration via hole that forms a penetration hole from the front surface of the board to the rear surface thereof, and an interstitial via hole that forms a penetration hole only between specific layers. Further, the interstitial via hole includes a blind via in which a hole is viewed from one surface of the board, as shown in  FIG. 4A , and a buried via in which a hole is not viewed from both surfaces of the board, as shown in  FIGS. 3A to 3E . 
     The example shown in  FIGS. 3A to 3E  and  4  uses a so-called four-layered board (four conductive layers including the front surface layer and the rear surface layer), but is not intended to limit the invention. For example, a multilayer board, such as a three-layered board, a six-layered board, or an eight-layered board, may be used. 
       FIG. 5  is diagram showing another example of the current detection printed board  1  according to the invention. The current detection printed board  1  shown in  FIG. 5  is different from that of  FIG. 1  in that two coiled wires  10 - 1  and  10 - 2  are provided in the current detection printed board  1 . Specifically, a first coiled wire  10 - 1  that is disposed near the outside of the current detection printed board  1  and a second coiled wire  10 - 2  that is disposed closer to the penetration hole  101  than the first coiled wire  10 - 1  does are provided in the current detection printed board  1 . Further, the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are formed by through holes and pattern wires, like  FIGS. 1B and 1C . For this reason, the descriptions thereof will be omitted. Of course, the multilayer board shown in  FIGS. 3A to 3E  may be used. Here, the description thereof will be omitted. 
     As described above, in the current detection printed board  1  shown in  FIG. 5 , since the two coiled wires  10 - 1  and  10 - 2  are provided, various kinds of current transformers can be formed in one current detection printed board  1 . This example will be described with reference to  FIG. 6 . 
       FIG. 6  is a connection diagram of the current detection printed board  1  shown in  FIG. 5 . 
     As shown in  FIG. 5 , output terminals  23 - 1  and  24 - 1  are connected to both ends  10 - 1   a  and  10 - 1   b  of the first coiled wire  10 - 1  via the output wires  21 - 1  and  22 - 1 . Further, output terminals  23 - 2  and  24 - 2  are connected to both ends  10 - 2   a  and  10 - 2   b  of the second coiled wire  10 - 2  via the output wires  21 - 1  and  22 - 1 . In this case, with the connection shown in  FIG. 6 , various kinds of current transformers can be formed in one current detection printed board  1 . Moreover, in  FIG. 6 , ‘(’ means non-connection to other terminals. 
     Specifically, in case of connection (a) in  FIG. 6 , a current transformer using the first coiled wire  10 - 1  is formed in the current detection printed board  1 . 
     In case of connection (b) in  FIG. 6 , a current transformer using the second coiled wire  10 - 2  is formed in the current detection printed board  1 . 
     In case of connection (c) in  FIG. 6 , if the output terminal  23 - 2  and the output terminal  24 - 1  are connected to each other, a current transformer when the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are connected in series to each other is formed. Therefore, in this case, a current transformer having larger inductance can be formed, compared with the cases (a) and (b) in  FIG. 6 . 
     In addition, like connection (d) in  FIG. 6 , if the output terminal  23 - 1  and the output terminal  23 - 2  are connected to each other, and the output terminal  24 - 1  and the output terminal  24 - 1  are connected to each other, a current transformer when the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are connected in parallel with each other. 
     In case of connection (a) in  FIG. 6 , the output wires  21 - 2  and  22 - 2  are not required. In case of connection (b) in  FIG. 6 , the output wires  21 - 1  and  22 - 1  are not required. For this reason, unnecessary output wires and output terminals may not be provided. 
       FIG. 7  is a diagram showing another example of the current detection printed board  1  according to the invention. In the current detection printed board  1 , like  FIG. 5 , the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are provided in one current detection printed board  1 . The current detection printed board  1  of  FIG. 7  is different from that of  FIG. 5  in that the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are disposed to have a double helix structure. Further, in  FIG. 7 , like  FIG. 5 , various kinds of current transformers can be formed in one current detection printed board  1 . Moreover, in  FIGS. 5 and 7 , for ease discrimination of the wires, the positions of the output terminals are shifted from each other, but the invention is not limited thereto. Various kinds of position relationship may be adopted. 
     As shown in  FIG. 7 , the first coiled wire  10 - 1  and the second coiled wire  10 - 2  can be arranged to have a double helix structure. Alternatively, many arrangement examples may be considered, in addition to the example shown in  FIG. 7 . 
       FIGS. 8A to 8E  are diagrams showing the arrangement examples of the first coiled wire  10 - 1  and the second coiled wire  10 - 2 .  FIGS. 8A  to BE schematically show the sections of the first coiled wire  10 - 1  and the second coiled wire  10 - 2  and show various arrangement examples. Moreover, the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are shifted from each other with respect to a backward direction as viewed from the paper. Since portions that are not typically viewed are shown in perspective view for explanation, the wires may seem to overlap each other. 
     For example,  FIG. 8A  shows an example where the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are formed in the same conductive layer. In this case, the pattern wire of the first coiled wire  10 - 1  is longer than that of the second coiled wire  10 - 2 . Of course, the pattern wire of the second coiled wire  10 - 2  may be longer than that of the first coiled wire  10 - 1 . 
       FIG. 8B  shows an example where the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are formed in the same conductive layer, like  FIG. 8A . However, the pattern wires of the first coiled wire  10 - 1  and the second coiled wire  10 - 2  have the same length. 
       FIG. 8C  shows an example where the through hole of the second coiled wire  10 - 2  is formed further towards the inside than the first coiled wire  10 - 1 , and the pattern wire of the second coiled wire  10 - 2  is formed in a conductive layer inside the first coiled wire  10 - 1 . 
       FIG. 8D  shows an example where the through hole of the second coiled wire  10 - 2  is formed further towards the inside than the first coiled wire  10 - 1 , and the pattern wire of the second coiled wire  10 - 2  is formed in a conductive layer outside the first coiled wire  10 - 1 . 
       FIG. 8E  shows an example where the through hole of the second coiled wire  10 - 2  is formed further towards the outside than the first coiled wire  10 - 1 , and the pattern wire of the second coiled wire  10 - 2  is formed in a conductive layer inside the first coiled wire  10 - 1 . 
     In addition, various modifications can be considered and easily considered from the above examples, and thus the descriptions thereof will be omitted. Moreover, as shown in  FIGS. 8A and 8B , when the pattern wires of the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are formed in the same conductive layer, a double-sided board can be used. 
     In  FIGS. 8A to 8E , as the current detection printed board  1  is viewed in plan view, the through holes and the pattern wires of the first coiled wire  10 - 1  and the second coiled wire  10 - 2  are shifted from each other. With this configuration, various arrangement examples can be made. Alternatively, as shown in  FIG. 8C , if the through hole of the second coiled wire  10 - 2  is formed further towards the inside than the through hole of the first coiled wire  10 - 1 , and the pattern wire of the second coiled wire  10 - 2  is formed further towards the inside than the pattern wire of the first coiled wire  10 - 1 , as viewed in plan view, the pattern wires of the first coiled wire  10 - 1  and the second coiled wire  10 - 2  may be partially overlap each other. Of course, the relationship between the first coiled wire  10 - 1  and the second coiled wire  10 - 2  may be reversed. 
     In  FIGS. 5 and 7 , an example where the two coiled wires  10  are provided in one current detection printed board  1  has been illustrated, but the number of coiled wires is not limited thereto. For example, three or more coiled wires  10  may be provided in one current detection printed board  1 . Of course, with this configuration, the number of combinations of the coiled wires  10  to be formed in one current detection printed board  1  can be increased. Further, as described below, when the current conversion circuit  51  is provided on the current detection printed board  1 , the same can be applied. In this case, as described above, the wires may be connected near both ends of the coiled wires  10  or may be connected in the current conversion circuit  51 . That is, both ends of each wire or positions electrically identical to both ends thereof are electrically connectable to both ends of another wire or positions electrically identical to both ends thereof. 
     Next, the effects of a case where a plurality of coiled wires  10  are provided in the current detection printed board  1 , as shown in  FIGS. 5 and 7 , will be described. 
     In general, a coil (also referred to as an inductor) has a frequency characteristic, and the characteristic changes according to a frequency to be used specifically, a detection level of a current is low in a region where a frequency is low. For this reason, the coil is used in a region where a frequency is high. However, an excessively high frequency causes resonance. A frequency at the time of resonance is referred to as a resonant frequency. Near the resonant frequency, a change in detection level of a current is excessively large, and thus it is unsuitable for current detection. For this reason, schematically, a detectable frequency band is limited. That is, a usable frequency has an upper limit and a lower limit. 
     If inductance of the coil becomes large, the detectable frequency band goes toward a lower frequency. Meanwhile, if inductance of the coil becomes small, the detectable frequency band goes toward a higher frequency. For this reason, it is necessary to select inductance of the coiled wire  10  to an appropriate value using a frequency of an AC current flowing in the power transmission conductor  66 . 
     The above-described high-frequency power supply device  61  outputs different frequencies of high-frequency power according to the uses. For example, a frequency of 2 MHz, 13.56 MHz, or the like is used according to the uses. For this reason, since it is necessary to select inductance of the coiled wire  10  according to the frequencies. Accordingly, if various kinds of current transformers can be formed in one current detection printed board  1 , convenience can be increased. For example, if both the current transformer for 2 MHz and the current transformer for 13.56 MHz can be formed, it is unnecessary to prepare the current detection printed boards  1  for the individual frequencies. Therefore, kinds of products can be reduced. 
     Like the examples shown in  FIGS. 1A to 1D  and  FIGS. 3A to 3E , when the coiled wire  10  is a simplex wound wire, there is a limit to increase the number of turns. Then, there is also a limit to increase inductance. Here, in case of serial connection indicated by (c) of  FIG. 6 , inductance of the coiled wire  10  can be increased, and thus the detectable frequency band can be made low. 
     (2) Voltage Detection Printed Board 
       FIGS. 9A to 9D  are diagrams showing an example of a voltage detection printed board  2  according to the invention. 
     Specifically,  FIG. 9A  is a plan view of the voltage detection printed board  2 .  FIG. 9B  is a schematic view of a portion (a portion C surrounded by a dotted line) of  FIG. 9A  on magnified scale.  FIG. 9C  is a diagram showing linear expansion for simplification of  FIG. 9B .  FIG. 9D  shows a wire of the voltage detection printed board  2  when  FIG. 9C  is viewed from the side. Moreover, as regards the wire shown in  FIG. 9D , portions that are not typically viewed are shown in perspective view for explanation. 
     As shown in  FIGS. 9A to 9D , the voltage detection printed board  2  has a penetration hole  201  that penetrates a board, and a ring-shaped wire  30  that is provided at the periphery of the penetration hole  201 . The ring-shaped wire  30  is formed by, along the periphery of the penetration hole  201 , providing a plurality of through holes  31  that penetrate the board and patterns wires  32  and  33  that connect the through holes to a front surface  221  and a rear surface  222  of the board. For this reason, the individual through holes are provided between the pattern wires  32  and  33  of the front surface of the rear surface of the board. Further, the thickness of each of the through holes is formed to have the substantially same thickness as the thickness of the board. In such a manner, the ring-shaped  30  is obtained. 
     Moreover, in  FIGS. 9B and 9C , the pattern wires  32  and  33  of the front surface and the rear surface of the board overlap each other. Further, an output wire  40  is connected to the ring-shaped wire  30 . 
     In the voltage detection printed board  2  in  FIGS. 9A to 9D , when a power transmission conductor  66 , in which an AC voltage is generated, is disposed to pass through the penetration hole  201 , the ring-shaped wire  30  and a portion of the power transmission conductor  66  facing the ring-shaped wire  30  function as electrodes of a capacitor. That is, the printed board can have a function as the electrodes of the capacitor. Accordingly, portions of the ring-shaped wire  30  correspond to the electrode  91   b  of the capacitor of the circuit diagram in  FIG. 27 . 
     With this configuration, the portions of the ring-shaped wire  30  are formed by the through holes  31  or the pattern wires  32  and  33 . Accordingly, there is almost no variation in shape or position. Therefore, when a plurality of voltage detection printed boards  2  are formed, a variation in voltage detection value of the individual voltage detection printed boards  2  can be reduced. 
     In particular, if AC power to be transmitted through the power transmission conductor  66  is AC power having a frequency of a radio frequency band, a structural variation in the voltage detection printed board  2  may have a large effect on the voltage detection value. However, according to the voltage detection printed board  2  having the above configuration, even though AC power having a frequency of a radio frequency band is adopted, an influence thereof can be suppressed to the minimum. 
     Moreover, as described below, a voltage conversion circuit  53  corresponding to the voltage conversion circuit  93  shown in  FIG. 36  maybe provided on the voltage detection printed board  2  of  FIGS. 9A to 9D . In this case, an output terminal  41  shown in  FIGS. 9A to 9D  is not required, and thus the output wire  40  of the ring-shaped wire  30  is directly connected to the voltage conversion circuit  53 . 
     Moreover, the ring-shaped wire  30  is an example of a third wire of the invention (a first wire in the case of a voltage detector), and the output wire  40  is an example of a fourth wire of the invention (a second wire in the case of a voltage detector). 
       FIGS. 10A to 10E  are diagrams showing another example of the voltage detection printed board  2  according to the invention. 
     Specifically,  FIG. 10A  is a plan view of the voltage detection printed board  2 .  FIG. 10B  is a schematic view of a portion (a portion D surrounded by a dotted line) of  FIG. 10A  on magnified scale.  FIG. 10C  is a diagram showing linear expansion for simplification of  FIG. 10B .  FIG. 10D  shows a wire of the voltage detection printed board  2  when  FIG. 10C  is viewed from the side.  FIG. 10E  shows the wire of the voltage detection printed board  2  paying emphasis on the output wire  40  as viewed from the side. Moreover, as regards the wire shown in  FIGS. 10A to 10E , portions that are not typically viewed are shown in perspective view for explanation. In addition, for convenience, the voltage detection printed board  2 , through holes  31 , pattern wires  32  and  33 , and the like are represented by the same reference numerals as those in  FIGS. 9A to 9D . 
     The voltage detection printed board  2  shown in  FIGS. 10A to 10E  is specifically the same as the voltage detection printed board  2  shown in  FIGS. 9A to 9D , except that the board has a multilayer structure, and the ring-shaped wire  30  is formed between inner layers. This is the same as  FIGS. 3A to 3E , and the description thereof will be omitted. 
     For this reason, in  FIGS. 10A to 10E , the ring-shaped wire  30  is formed between a first conductive layer  231  and a second conductive layer  232 . Accordingly, the ring-shaped wire  30  may not be viewed. Further, in this case, the portions of the ring-shaped wire  30  correspond to the electrode  91   b  of the capacitor of the circuit diagram in  FIG. 36 . 
     The ring-shaped wire  30  is formed by pattern wires  40   a  connected to one end  30   a  of the ring-shaped wire  30  formed in the first conductive layer  231 , through holes  40   b , and pattern wires  40   c  formed on the front surface of the board  40   c , as shown in  FIG. 10E . The output wire  40  is connected to an output terminal  41 . 
     Moreover, unlike the above description, as shown in  FIGS. 11A and 11B , the ring-shaped wire  30  may be formed. 
       FIGS. 11A and 11B  show another example of the ring-shaped wire  30 . 
       FIG. 11A  shows an example where an additional pattern wire for connecting the through holes is provided between a top conductive layer and a bottom conductive layer at penetration portions of the through holes  31 . In this example, four pattern wires of a pattern wire  34 , a pattern wire  35 , a pattern wire  36 , and a pattern wire  37  are provided in sequence from the upper portion of the board. As such, three or more pattern wires may be provided. 
       FIG. 11B  shows an example where a pattern wire  38  is provided in only one layer between the top conductive layer and the bottom conductive layer at the penetration portions of the through holes  31 . As such, only one pattern wire may be provided. 
     Accordingly, a pattern wire may be provided in at least one layer between the top conductive layer and the bottom conductive layer at the penetration portions of the through holes so as to connect the through holes. In this case, the portions of the ring-shaped wire  30  correspond to the electrode  91   b  of the capacitor of the circuit diagram in  FIG. 27 . 
     (3) Current/Voltage Detector 
       FIGS. 12A to 12C  are schematic exterior views of a current/voltage detector  3   a  according to a third embodiment of the invention. Specifically,  FIG. 12A  is a schematic exterior view three-dimensionally showing the current/voltage detector  3   a .  FIG. 12B  is a schematic exterior view of a conductor casing as viewed from the side.  FIG. 12C  is a diagram when the conductor casing of  FIG. 12B  is removed. 
     As shown in  FIG. 12A , like the related art, the current/voltage detector  3   a  has a structure in which a power transmission conductor  66  can penetrate a casing. Moreover, the power transmission conductor  66  and an insulator  69  surrounding the power transmission conductor  66  are not included in the current/voltage detector  3   a  but are just shown for explanation. Further, the insulator  69  insulates the power transmission conductor  66  and the current/voltage detector  3   a  For this reason, an actual length of the insulator  69  is shorter than the length of the insulator  69  shown in the drawing, but it is shown like  FIG. 12A  for simplification of the drawing. The same is applied to other drawings. 
     As shown in  FIG. 12C , the current detection printed board  1  and the voltage detection printed board  2  are accommodated in the casing. For this reason, a current that flows in the power transmission conductor  66  passing through the casing can be detected by the current detection printed board  1 , and a voltage that is generated in the power transmission conductor  66  can be detected by the voltage detection printed board  2 . 
     That is, in the example shown in  FIG. 12B , a left portion of the current/voltage detector  3   a  corresponds to a current detector  340  and a right portion thereof corresponds to a voltage detector  350 . Moreover, the casing is formed of a conductor, such as aluminum or the like. Then, the current detector  340  corresponds to the current detector  80  shown in  FIG. 36 , and the voltage detector  350  corresponds to the voltage detector  90  shown in  FIG. 36 . 
       FIGS. 13A and 13B  are diagrams showing the schematic configuration of the current/voltage detector  3   a  shown in  FIGS. 12A to 12C . Specifically,  FIG. 13A  is a diagram showing the configuration of the current/voltage detector  3   a .  FIG. 13B  is a schematic view showing when individual parts of  FIG. 13A  are assembled. Moreover, in  FIGS. 13A and 13B , the shapes of the individual parts are schematic. For example, a penetration hole through which the power transmission conductor  66  passes or an opening through which a magnetic flux passes is provided in the casing or the board, but it is not shown in the drawings. Further, in  FIGS. 13A and 13B , portions that are not viewed front the outside are schematically indicated by dotted lines. 
     As shown in  FIG. 13A , the current/voltage detector  3   a  has a casing main body  330 , and the current detection printed board  1 , the voltage detection printed board  2 , a current detector cover  331 , and a voltage detector cover  332  that are fixed to the casing main body  330 . Of course, parts, such as screws or beads, for fixing the above-described constituents, but they are regarded as portions of the constituents and are not shown for simplification of explanation. Further, as indicated by an arrow in  FIG. 13A , if the constituents are fixed to the casing main body  330 , as shown in  FIG. 13B , the current detection printed board  1  and the voltage detection printed board  2  are fixed in the casing main body  330 , and the current detection printed board  1  and the voltage detection printed board  2  are covered with the covers  331  and  332 , respectively. 
     That is, like the related art, the current detection printed board  1  and the voltage detection printed board  2  are disposed in the casing. The casing main body  330  is common to the current detection printed board  1  and the voltage detection printed board  2 . Then, if the current detection printed board  1  is fixed on the front surface of the casing main body  330 , the voltage detection printed board  2  is fixed on the rear surface thereof. Accordingly, the current detection printed board  1  and the voltage detection printed board  2  are accommodated in separate spaces, respectively. 
       FIG. 14  is a cross-sectional view of the current/voltage detector  3   a  shown in  FIG. 12B . Current detection by the coiled wire  10  will be supplemented with reference to  FIG. 14 . 
     In the current detection printed board  1 , a magnetic flux required for current detection should act on the coiled wire  10 , but it is not desirable that the coiled wire  10  comes under the influence of an electric fields For this reason, as shown in  FIG. 14 , a casing is adapted such that part of the casing is disposed between the power transmission conductor  66  and the current detection printed board  1  (accurately, between the insulator  69  covering the power transmission conductor  66  and the current detection printed board  1 ). If doing so, an influence of the electric field on the coiled wire  10  is reduced, and thus current detection accuracy can be increased. 
     With the current detection printed board  1  and the voltage detection printed board  2 , when a plurality of printed boards are formed, a variation in detection value of the individual printed boards can be reduced. 
     However, as shown in  FIGS. 12A to 12C , in the current/voltage detector  3   a  that uses the current detection printed board  1  and the voltage detection printed board  2 , the current detection point of the current detection printed board  1  and the voltage detection point of the voltage detection printed board  2  are structurally slightly away from each other in the axial direction of the power transmission conductor  66 . That is, a current and a voltage at slightly different points are detected. 
     Of course, in terms of a phase difference calculated from the detection current and voltage, a current amplitude detection value, and a voltage amplitude detection value, the current detection point and the voltage detection point are preferably the same. 
     For this reason, it is desirable to approximate the current detection point and the voltage detection point. However, as shown in  FIGS. 12A to 12C , it is structurally difficult to perform current detection and voltage detection in different printed boards. 
     Now, a current/voltage detection printed board that can further approximate the current detection point and the voltage detection point, and a current/voltage detector using the printed board will be described. 
     (4) Current/Voltage Detection Printed Board 
     Although an example in which the coiled wire  10  and the ring-shaped wire  30  are formed in different printed boards has been hitherto described, as shown in  FIGS. 15A to 15E , they may be formed in the same printed board. This example will be described with reference to  FIGS. 15A to 15E . 
       FIGS. 15A to 15E  are diagrams showing an example of a current/voltage detection printed board  4  according to the invention. 
     Specifically,  FIG. 15A  is a plan view of a current/voltage detection printed board  4  (as viewed from the above).  FIG. 15B  is a schematic view of a portion (a portion E surrounded by a dotted line) of  FIG. 1A  on magnified scale.  FIG. 15C  is a diagram showing linear expansion for simplification of  FIG. 15B .  FIG. 15D  is a schematic view when a portion of  FIG. 15C  is viewed from the side.  FIG. 15E  is a cross-sectional view taken along the line F-F of  FIG. 15A . 
     As shown in  FIG. 15A , a current/voltage detection printed board  4  is provided with a penetration hole  401  that penetrates the board. A ring-shaped wire  30  is formed at the periphery of the penetration hole  401 . An output wire  40  and an output terminal  41  are connected to the ring-shaped wire  30 . 
     A shield portion  500  having a shield function is formed outside the ring-shaped wire  30 . The shield portion  500  will be described below. 
     A coiled wire  10  is formed outside the shield portion  500 . Output wires  21  and  22  are connected to the coiled wire  10 . Output terminals  23  and  24  are connected to the output wires  21  and  22 , respectively. 
     The coiled wire  10  is the same as that shown in  FIG. 1A . Although the coiled wire  10  shown in  FIG. 1A  is formed at the periphery of the penetration hole  101 , and the coiled wire  10  shown in  FIG. 15A  is formed outside the shield portion  500 , both the coiled wires  10  function as a current transformer. The output wires  21  and  22  and the output terminals  23  and  24  are the same as those shown in  FIG. 1A . 
     The ring-shaped wire  30  is the same as that shown in  FIG. 9A . Although the ring-shaped wire  30  shown in  FIG. 9A  is formed at the periphery of the penetration hole  201 , and the ring-shaped wire  30  shown in  FIG. 15A  is formed at the periphery of the penetration hole  401 , both the ring-shaped wires  30  function as an electrode of a capacitor. As shown in  FIG. 19A , the output wire  40  is slightly different from that shown in  FIG. 9A , but it has a function to output a voltage generated in the ring-shaped wire  30 , similarly to that shown in  FIG. 9A . 
     As such, the coiled wire  10  and the like are different from those shown in  FIG. 1A , but they have the same basic configuration. In addition, the ring-shaped wire  30  and the like are different from those shown in  FIG. 9A , but they have the same basic configuration. Thus, detailed descriptions of the coiled wire  10  and the like, and the ring-shaped wire  30  will be omitted. Moreover, for convenience of explanation, constituents having the same functions as those described above are represented by the same reference numerals. 
     The current/voltage detection printed board  4  includes the coiled wire  10  and the ring-shaped wire  30 , and thus it has a voltage detection function and a current detection function. The voltage detection point and the current detection point can be substantially the same. 
     If AC power to be transmitted through the power transmission conductor  66  is AC power having a frequency of a radio frequency band, a variation in winding interval or winding strength in the coiled wire  10  may have a large effect on the current detection value. In addition, a structural variation in the ring-shaped wire  30  may have a large effect on the voltage detection value. However, according to the current/voltage detection printed board  4  having the above configuration, even though AC power having a frequency of a radio frequency band is adopted, an influence thereof can be suppressed to the minimum. 
     Next, the shield portion  500  will be described. The shield portion  500  is formed by arranging a plurality of through holes  501  and  502  in a substantially circuit shape, as shown in  FIGS. 15B and 15C . Specifically, the shield portion  500  is formed by arranging a plurality of through holes in a substantially circuit shape and in at least two lines. 
     In the illustrated example, a plurality of through holes  501  are arranged inside of the shield portion  500  (a side close to the penetration hole  401 ) in a substantially circular shape, and a plurality of through holes  502  are arranged outside the shield portion  500  in a substantially circuit shape. The through holes  501  and the through holes  502  are arranged with a position shift. For this reason, when the shield portion  500  is viewed from the side, the through holes  501  and the through holes  502  overlap each other, and a gap disappears. Therefore, the shield portion  500  shields an electric field generated when the power transmission conductor  66  is disposed to pass through the penetration hole  401 . In addition, since the through holes can be easily formed in manufacturing the printed board, the shield portion  500  is easily formed. 
     As shown in  FIG. 28  and the like, the shield portion  500  needs to be connected to the casing. The single current/voltage detection printed board  4  does not have a shield function of the shield portion  500 . However, as for the structure of the current/voltage detection printed board, as described above with reference to  FIGS. 15A to 15E , the shield portion  500  needs to be provided between the coiled wire  10  and the ring-shaped wire  30 . 
     In  FIGS. 15A to 15E , the shield portion  500  is formed by the through holes arranged double, but the through holes may be arranged in three lines or more. In this case, according to the above concept, it is preferable to make a gap between the through holes forming the shield portion  500  disappear as the shield portion  500  is viewed from the side. 
       FIG. 15D  is a schematic view when the plurality of through holes  501  shown in  FIG. 15C  are viewed from the side. As shown in  FIG. 15D , the current/voltage detection printed board  4  is a multilayer board. In addition, as shown in  FIG. 15D , the through holes  501  include upper through holes  501   a  and lower through holes  501   b , and are formed so as not to pass through the board. Though not shown in  FIG. 15D , similarly, the through holes  502  include upper through holes  502   a  and lower through holes  502   b , and are formed so as not to pass through the board. That is, the shield portion  500  is provided with an unshielded portion between the front surface and the rear surface of the board. This will also be apparent from  FIG. 15E .  FIG. 15E  is a cross-sectional view taken along the line F-F of  FIG. 15A , which schematically shows an example of the shield portion  500  and the like. 
     Ad described above, the shield portion  500  is formed in a substantially circular shape, but the invention is not limited thereto. What is necessary is that the shield portion  500  is provided between the coiled wire  10  and the ring-shaped wire  30 . Therefore, the shield portion  500  may have an elliptical shape or may partially have a linear shape. If the coiled wire  10  and the ring-shaped wire  30  substantially have a circular shape, in terms of reduction in area, the shield portion  500  may also substantially have a circular shape. 
       FIGS. 16A to 16E  are diagrams showing another example of the current/voltage detection printed board  4  according to the invention. Specifically,  FIG. 16A  is a plan view of the current/voltage detection printed board  4  (as viewed from the above).  FIG. 16B  is a schematic view of a portion (a portion G surrounded by a dotted line) of  FIG. 16A  on magnified scale.  FIG. 16C  is a diagram of showing linear expansion for simplification of  FIG. 16B .  FIG. 16D  is a schematic view when a portion of  FIG. 16C  is viewed from the side.  FIG. 16E  is a cross-sectional view taken along the line H-H of  FIG. 16A . 
     The current/voltage detection printed board  4  shown in  FIG. 16A  includes a coiled wire  10  and a ring-shaped wire  30 , which are different from those in  FIG. 15A . 
     Specifically, the coiled wire  10  shown in  FIG. 16A  is the same as that shown in  FIG. 3A  and the ring-shaped wire  30  is the same as that shown in  FIG. 10A . A shield portion  500  is the same as that shown in  FIG. 15A . Thus, detailed descriptions thereof will be omitted. Moreover, for convenience of explanation, constituents having the same functions as those described above are represented by the same reference numerals. 
     Similarly to  FIG. 15A , the coiled wire  10  and the like are different from those shown in  FIG. 3A , but they have the same basic configuration. The coiled wire  10  functions as a current transformer. In addition, the ring-shaped wire  30  and the like are different from those shown in  FIG. 10A , but they have the same basic configuration. The ring-shaped wire  30  functions as an electrode of a capacitor. 
     As such, other examples of the coiled wire  10  or the ring-shaped wire  30  described hitherto may be used. For this reason, as for the coiled wire  10 , the coiled wires  10  shown in  FIGS. 5 ,  7 , and  8 A to  8 E, and the equivalents thereof may be used. As for the ring-shaped wire  30 , the ring-shaped wires  30  shown in  FIGS. 11A and 11B  and the equivalents thereof may be used. 
     The output wire  40  that is connected to the ring-shaped wire  30  will now be described. 
       FIGS. 17A and 17B  are diagrams showing an example of the output wire  40  that is connected to the ring-shaped wire  30 . Specifically,  FIG. 17A  is a plan view of the current/voltage detection printed board  4  (as viewed from the above), and  FIG. 17B  is a partial cross-sectional view of a portion (a portion J surrounded by a dotted line) of  FIG. 17A  as viewed from the side. Moreover,  FIG. 17B  schematically shows an example of a section. 
     As shown in  FIGS. 17A and 17B , the output wire  40  that is connected to the ring-shaped wire  30  passes through a portion near the center of the board ring-shaped wire  30  from a portion near the center of the through hole, and is led to the surface of the board and connected to the output terminal  41 . 
       FIGS. 18A and 18B  are diagrams showing anther example of the output wire  40  that is connected to the ring-shaped wire  30 . Specifically,  FIG. 18A  is a plan view of the current/voltage detection printed board  4  (as viewed from the above).  FIG. 10B  is a partial cross-sectional view of a portion (a portion K surrounded by a dotted line) of  FIG. 18A  as viewed from the side. Moreover,  FIG. 18B  schematically shows an example of a section. 
       FIGS. 18A and 18B  are basically the same as  FIGS. 17A and 17B , except that the output wire  40  passes through the coiled wire  10 .  FIG. 18B  schematically shows an example of a section, and thus, in  FIG. 18B , the output wire  40  and the coiled wire  10  seem to overlap each other. However, actually, they are formed so as not to be in contact with each other. 
       FIGS. 19A and 19B  are diagrams showing another example of the output wire  40  that is connected to the ring-shaped wire  30 . Specifically,  FIG. 19A  is a plan view of the current/voltage detection printed board  4  (as viewed from the above).  FIG. 19B  is a partial cross-sectional view of a portion (a portion L surrounded by a dotted line) a) of  FIG. 19A  as viewed from the side. Moreover,  FIG. 19B  schematically shows an example of a section. 
       FIGS. 19A and 19B  are similar to  FIGS. 18A and 18B , except that the output wire  40  is formed on the surface of the board, and passes through the coiled wire  10 .  FIG. 19B  schematically shows an example of a section, and thus, in  FIG. 19B , the output wire  40  and the coiled wire  10  seems to overlap each other. However, actually, they are formed so as not to be in contact with each other. 
     The shield portion  500  is basically formed as described with reference to  FIGS. 15B to 15D , but a portion through which the output wire  40  passes is formed as described with reference to  FIG. 19B . That is, only a portion near the surface of the board is unshielded. As such, the shield portion  500  may be formed in such a manner that a portion is different from other portions. As shown in  FIG. 19A , the shield portion  500  including a cutout portion substantially has a circular shape. 
       FIGS. 20A and 20B  are diagrams showing another example of the output wire  40  that is connected to the ring-shaped wire  30 . Specifically,  FIG. 20A  is a plan view of the current/voltage detection printed board  4  (as viewed from the above).  FIG. 20B  is a partial cross-sectional view of a portion (a portion M surrounded by a dotted line) of  FIG. 20A  as viewed from the side. Moreover,  FIG. 20B  schematically shows an example of a section. 
       FIGS. 20A and 20B  are similar to  FIGS. 19A and 19B , but a ring-shaped wire  30  and a coiled wire  10  are different from those shown in  FIGS. 19A and 19B . 
     Specifically, the ring-shaped wire  30  shown in  FIG. 16A  is the same as that shown in  FIG. 10A  and the coiled wire  10  is the same as that shown in  FIG. 3A . That is, the configuration shown in  FIGS. 20A and 20B  is the combination of  FIG. 16A  and  FIG. 18A . 
     As such, various aspects of the output wire  40  that is connected to the ring-shaped wire  30  can be considered. In addition, various aspects of the shield portion  500  can also be considered. 
     (5) Current/Voltage Detector (Second Example): 
       FIG. 21  is a schematic exterior view three-dimensionally showing a current/voltage detector  3   b  according to the invention. 
     As shown in  FIG. 21 , the current/voltage detector  3   b  has such a structure that a power transmission conductor  66  can pass through a casing, like the related art. The power transmission conductor  66  and an insulator  69  at the periphery of the power transmission conductor  66  are not included in the current/voltage detector  3   b  but are just shown for explanation. The insulator  69  insulates the power transmission conductor  66  from the current/voltage detector  3   b . For this reason, the actual length of the insulator  69  is shorter than the length of the insulator  69  shown in the drawing, but it is shown like  FIG. 21A  for simplification of the drawings. The same is applied to other drawings (for example,  FIG. 28 ). Moreover, the casing is formed of a conductor, such as aluminum. 
       FIG. 22  is a diagram showing the schematic configuration of the current/voltage detector  3   b  shown in  FIG. 21 . In  FIG. 22 , the shapes of the individual constituents are schematic. For example, a penetration hole through which the power transmission conductor  66  passes is provided in the casing or the board, but it is not shown in the drawing. 
     As shown in  FIG. 22 , the current/voltage detector  3   b  includes a casing main body  300 , a current/voltage detection printed board  4  fixed to the casing main body  300 , and a cover  301 . Of course, parts, such as screws or beads, for fixing the above-described constituents are also included, but they are regarded as portions of the constituents and are not shown for simplification of explanation. The cover  301  is a portion of the casing and is formed of a conductor, such as aluminum. In addition, as indicated by arrows in  FIG. 22 , if the constituents are fixed to the casing main body  300 , the current/voltage detection printed board  4  is fixed in the casing main body  300 , and the current/voltage detection printed board  4  is covered with the cover  301 . 
     Next, other portions than the cover  301  will be described in detail. 
       FIGS. 23A and 23B  are diagrams of the casing main body  300 . Specifically,  FIG. 23A  is a cross-sectional view of a side surface of the casing main body  300 .  FIG. 23B  is a plan view as viewed from a side on which the current/voltage detection printed board  4  is fixed. 
       FIG. 24  is a diagram three-dimensionally showing the casing main body  300 . 
       FIG. 25  is a diagram when the current/voltage detection printed board  4  is mounted on the casing main body  300  in a state where the cover  301  is not mounted. The current/voltage detection printed board  4  is, for example, the same as that shown in  FIG. 19A . 
     As shown in  FIGS. 23A and 23B ,  24 , and  25 , the casing main body  300  is provided with a penetration hole  303  and concave portions  311  and  312 . Therefore, the power transmission conductor  66  and the insulator  69  covering the power transmission conductor  66  can pass through the casing main body  300 , and the current/voltage detection printed board  4  can be accommodated in the casing. 
     A first casing shield portion  306  is a portion of the casing main body  300 , and when the current/voltage detection printed board  4  is mounted on the casing main body  300 , it is connected to the shield portion  500 . That is, the first casing shield portion  306  is formed in a substantially circular shape according to the shape of the shield portion  500 . Of course, as described above, when the shield portion  500  does not have a substantially circular shape, the first casing shield portion  306  may be formed to have a shape according to the shape of the shield portion  500 . The first casing shield portion  306  may be detachably provided, for example, by screws. In this case, the first casing shield portion  306  is also regarded as a portion of the casing main body  300 . In addition, the first casing shield portion  306  is formed of a conductor, such as aluminum, similarly to the casing main body  300 . 
     Though not shown in  FIGS. 23A and 23B ,  24 , and  25 , the cover  301  is provided with a second casing shield portion  307 , which is the same as the first casing shield portion  306 , as shown in  FIG. 28  and the like. Specifically, after the current/voltage detection printed board  4  is mounted on the casing main body  300 , when the cover  301  is mounted on the casing main body  300 , the second casing shield portion  307  is connected to the shield portion  500 . That is, the second casing shield portion  307  is formed in a substantially circuit shape according to the shape of the shield portion  500 . 
     The second casing shield portion  307  may be detachably provided, for example, by screws. In this case, the second casing shield portion  307  is also regarded as a portion of the cover  301 . In addition, the second casing shield portion  307  is formed of a conductor, such as aluminum. The functions of the shield portion  500  and the like will be described below. 
     Four board fixing portions  315 s are provided at four corners of the concave portion  311 , and the current/voltage detection printed board  4  is fixed to the portions. This is to allow the current/voltage detection printed board  4  to float with respect to the bottom surface of the concave portion  311  such that the wire provided in the current/voltage detection printed board  4  does not come into contact with the casing (the shield portion  500  is not regarded to as a wire). 
     For example, unlike  FIGS. 16A to 16E , when the coiled wire  10  and the ring-shaped wire  30  of the current/voltage detection printed board  4  are not formed on the rear surface layer of the board, the board fixing portions  315  provided at the four corners of the concave portion  311  can be removed. Then, the bottom surface of the concave portion  311  can have the same height as the bottom surface of the concave portion  312 . In addition, the first casing shield portion  306  is not required. 
       FIG. 26  is a diagram three-dimensionally showing the casing main body  300  when no board fixing portion  315  is provided. With the configuration as shown in  FIG. 26 , the structure of the casing main body  300  can be simplified. 
     Usually, the cylindrical (a circular shape in section) power transmission conductor  66  is used, and accordingly the penetration hole  303  provided in the casing main body  300  also has a circular shape. In addition, the penetration hole  401  of the current/voltage detection printed board  4  has a circular shape, and the ring-shaped wire  30  is formed in a circuit shape along the periphery of the penetration hole  401 . 
     Next, the current/voltage detection printed board  4  will be described. 
     The coiled wire  10  of the current/voltage detection printed board  4  is the same as described with reference to  FIGS. 19A and 19B , and the output wires  21  and  22  are connected to the current conversion circuit  51  in forms of pattern wires. The current conversion circuit  51  corresponds to the current conversion circuit  84  shown in  FIG. 36 . 
     The ring-shaped wire  30  of the current/voltage detection printed board  4  is the same as described with reference to  FIGS. 19A and 19B , and the output wire  40  is connected to the voltage conversion circuit  53  in forms of the pattern wire. The voltage conversion circuit  53  corresponds to the voltage conversion circuit  93  shown in  FIG. 36 . 
     Therefore, unlike the current/voltage detection printed board  4  described with reference to  FIGS. 19A and 19B , the coiled wire  10 , the ring-shaped wire  30 , the current conversion circuit  51 , and the voltage conversion circuit  53  are provided on the same board. 
     An output wire  52  connected to the current conversion circuit  51  extends toward the outside of the casing through a wire opening  316 . Moreover, the current conversion circuit  51  has an output terminal to which the output wire  52  is connected. The output wire  52  may be partially a pattern wire or may be overall a wire other than the pattern wire. 
     An output wire  54  connected to the voltage conversion circuit  53  extends towards the outside of the casing through the wire opening  316 . Moreover, the voltage conversion circuit  53  has an output terminal to which the output wire  54  is connected. The output wire  54  may be partially a pattern wire or may be overall a wire other than the pattern wire. In this example, the output wire  52  and the output wire  54  extend towards the outside of the casing through the same opening  316 , but they may extend towards the outside of the casing through different openings. 
     If AC power to be transmitted through the power transmission conductor  66  is AC power having a frequency of a radio frequency band, a variation in winding interval or winding strength of the coiled wire  10  has a large effect on the current detection value. In addition, a structural variation in the ring-shaped wire  30  has a large effect on the voltage detection value. A variation in the shape of the output wire also has an effect on the detection value. However, according to the current/voltage detection printed board  4  having the above configuration, even though AC power having a frequency of a radio frequency band is adopted, an influence thereof can be suppressed to the minimum. 
     In the casing main body  300 , a third casing shield portion  308  is provided at a corresponding position between the coiled wire  10  of the current/voltage detection printed board  4  and the current conversion circuit  51 . For this reason, the current/voltage detection printed board  4  has a partially narrow width according to the third casing shield portion  308 . 
     In this example, the third casing shield portion  308  has a function to shield a space where the coiled wire  10  and the ring-shaped wire  30  are provided and a space where the current conversion circuit  51  and the voltage conversion circuit  53  are provided. 
       FIGS. 27A and 27B  show an example of an application of the third casing shield portion  308 . 
     As shown in  FIGS. 23A and 23B , and  24  to  26 , since only with the third casing shield portion  308  of the casing main body  300 , a gap occurs in the output wires, shield may not be sufficient. In this case, as shown in  FIG. 27A , a shield portion  317  for burying the gap may be provided in the cover  301 . In such a manner, the gap in the output wires is almost removed, and thus a shield effect increases. In addition, as shown in  FIG. 27B , instead of the third casing shield portion  308 , a shield portion  318  may be provided in the cover  301 . 
     Next, the shield function of the shield portion  500  will be described. 
       FIG. 28  shows an example of a cross-sectional view when the current/voltage detection printed board  4  is accommodated in the casing. Specifically,  FIG. 28  schematically shows a section taken along the line N-N of  FIG. 25  in a state where the cover  301  is mounted. 
     As shown in  FIG. 28 , in a state where the current/voltage detection printed board  4  is accommodated, when the power transmission conductor  66  used as an AC power transmission path is disposed to pass through the penetration hole  401 , the ring-shaped wire  30  functions as an electrode of a capacitor. This is, for example, the same as a case where the voltage detection printed board  2  shown in  FIG. 9A  is accommodated in the casing, as shown in  FIG. 12B . 
     However, the coiled wire  10  is different from a case where the current detection printed board  1  shown in  FIG. 1A  is accommodated in the casing, as shown in  FIG. 12B . That is, considering the coiled wire  10  only, as described above, the coiled wire  10  of the current detection printed board  1  shown in  FIG. 1A  and the like is the same as the coiled wire  10  of the current/voltage detection printed board  4  shown in  FIG. 15A  or the like. However, in case of the connection state shown in  FIG. 28 , the ring-shaped wire  30  is provided between the power transmission conductor  66  and the coiled wire  10 . Accordingly, it is different from the connection state shown in  FIG. 12B . 
     Considering that no shield portion  500  is provided, a space between the coiled wire  10  and the ring-shaped wire  30  is not shielded, and accordingly a magnetic flux required for current detection acts on the coiled wire  10 . At this time, the coiled wire  10  comes under the influence of an electric field. However, as described above, it is not desirable that the coiled wire  10  comes under the influence of the electric field, and in this case, current detection accuracy may be lowered. For this reason, even though the coiled wire  10  and the ring-shaped wire  30  are provided in the same board, it is necessary to reduce the influence of the electric field on the coiled wire  10 , thereby increasing the current detection accuracy. 
     Therefore, the shield portion  500  and the shield portions above and below the shield portion  500  (the first casing shield portion  306  and the second casing shield portion  307 ) are provided to shield the space between the coiled wire  10  and the ring-shaped wire  30  as large as possible. Of course, since the magnetic flux required for current detection should act on the coiled wire  10 , the space is not completely shielded, and a partially unshielded portion is provided. 
     From a viewpoint of shield, the unshielded portion is preferably as small as possible, but in terms of current detection by the coiled wire  10  or the output wires described with reference to  FIGS. 17A and 17B  and the like, it is preferable to design the shield portion in consideration of this balance. In any cases, the influence of the electric field on the coiled wire  10  can be reduced, as compared with a case where no shield portion  500  is provided, and the magnetic flux required for current detection can act on the coiled wire  10 . 
     Therefore, in the current/voltage detector shown in  FIGS. 12A to 12C , a problem that the current detection point and the voltage detection point are away from each other can be resolved, and the current detection point and the voltage detection point can be substantially the same. 
     As will be apparent from the above description, the shield portion  500  is connected to the first casing shield portion  306  and the second casing shield portion  307  above and below the shield portion  500 . Then, the shield portion  500  is electrically connected to the casing. Therefore, the shield portion  500  has a shield function. 
     Although the ring-shaped wire  30  and the shield portion  500  are both formed by the through holes, both are different from each other in structure and function. 
       FIGS. 29A and 29B  are another example of cross-sectional views when the current/voltage detection printed board  4  is accommodated in the casing. 
     Unlike  FIG. 28 ,  FIG. 29A  shows an example where the through holes forming the shield portion  500  are not divided into two groups, but are provided in the board, excluding the front surface of the board. That is, a so-called blind via is formed. As such, the shield portion  500  has a configuration different from that shown in  FIG. 28 , but it is the same as that shown in  FIG. 28  in that an unshielded portion is provided in a portion between the front surface and the rear surface of the board. In such a manner, similarly to  FIG. 28 , an electric field is shielded, and a magnetic flux acts on the coiled wire  10 . 
     In  FIG. 29B , unlike  FIG. 28 , the through holes forming the shield portion  500  pass through the board. Instead, the second casing shield portion  307  is not connected to the shield portion  500 , and thus a gap is empty. In this case, although no unshielded portion is provided in a portion between the front surface and the rear surface of the board, the same effects as those in  FIGS. 28 and 29A . That is, similarly to  FIG. 28 and 29A , an electric field is shielded, and a magnetic flux acts on the coiled wire  10 . 
       FIGS. 30A and 30B  are another example of cross-sectional views when the current/voltage detection printed board  4  is accommodated in the casing. 
       FIG. 30A  shows an example where the casing main body  300  shown in  FIG. 26  and the current/voltage detection printed board  4  shown in  FIG. 16A  are used. That is, since the coiled wire  10  and the ring-shaped wire  30  are formed between inner layers, the casing main body  300  shown in  FIG. 26  can be used, and the first casing shield portion  306  can be removed. In this case, the through holes forming the shield portion  500  are connected to the casing main body  300 , and thus the same effects as those in  FIG. 28  and  FIGS. 29A and 29B  are obtained. 
       FIG. 30B  shows an example where the second casing shield portion  307  is removed, and the casing main body  300  is adapted such that the through holes are connected to the cover  301 . In this case, the same effects as those in  FIG. 28  and  FIGS. 29A and 29B  are obtained. 
     Modifications of Current/Voltage Detector 
       FIG. 31  shows a current/voltage detector  3   c  as a modification of the current/voltage detector  3   b . Here, a cover  301   a  is not shown. Specifically,  FIG. 31  shows a case where the current/voltage detection printed board  4  is the same as that shown in  FIGS. 19A and 19B . As shown in  FIG. 31 , the current conversion circuit  51  and the voltage conversion circuit  53  may be provided outside the current/voltage detector  3   c . The casing includes a casing main body  300   a  having a shape for the current/voltage detection printed board  4 . The output of the current/voltage detection printed board  4  is output outside the casing by output wires, not pattern wires. In this case, the current conversion circuit  51  and the voltage conversion circuit  53  are provided separately outside the current/voltage detector  3   c.    
       FIG. 32  shows a current/voltage detector  3   d  as a modification of the current/voltage detector  3   b . Here, a cover  301   b  is not shown. As shown in  FIG. 32 , the current conversion circuit  51  and the voltage conversion circuit  53  may be provided on the current/voltage detection printed board  4 . Moreover, the output wire of the current conversion circuit  51  and the output wire of the voltage conversion circuit  53  may be partially pattern wires or may be overall wires other than the pattern wires. 
     Although an example where the current/voltage detector  3   a ,  3   b ,  3   c , or  3   d  is provided at the input terminal  63   a  of the impedance matching device has been described in the above description, the invention is not limited thereto. For example, the detector may be provided at an output terminal of the high-frequency power supply device  61 , or may be provided at the output terminal  63   b  of the impedance matching device. Moreover, as described above, there is a difference in current and voltage at the input terminal  63   a  and the output terminal  63   b  (the same as the input terminal of the load  65 ) of the impedance matching device). For this reason, when the detector is provided at the output terminal  63   b  of the impedance matching device or the input terminal of the load  65 , in order to extend an insulation distance, it is preferable to use a power transmission conductor  68  having a large diameter or a thick insulator  69  covering the periphery of the power transmission conductor  68  in consideration of the difference. Furthermore, the detector may be used for other systems than the high-frequency power supply system. 
     (6) Fixing Method 
     When the outer diameter of the insulator  69  and the inner diameter of the penetration hole  303  provided in the casing main body  300  are substantially consistent with each other, the insulator  69  and the current/voltage detector  3   b  can be fixed. However, actually, the insulator  69  having an outer diameter smaller than the inner diameter of the penetration hole may be used. In this case, a gap occurs between the insulator  69  and the casing main body  305 . As such, if the gap exists, when the power transmission conductor  66  and the current/voltage detector  3   b  are mounted on the impedance matching device  63 , the relative position therebetween may not be constant according to mounting devices. That is, the relative position between the power transmission conductor  66  and the current/voltage detection printed board  4  may not be constant. In this case, when a plurality of devices are formed, a variation in detection value of the individual devices occurs. For this reason, when the gap is large, it is preferable to keep the relative position between the power transmission conductor  66  and the current/voltage detector  3   b  constant. 
       FIG. 33  is a diagram showing a fixing method of the insulator  69 . As shown in  FIG. 33 , a concave portion is provided in the insulator  69 , and a cover  301  is fitted into the concave portion. With this configuration, the insulator  69  can be fixed by the cover  301 . Moreover, the cover  301  may be divided into two parts at a portion near the penetration hole. If doing so, even through the outer diameter of the insulator  69  is smaller than the inner diameter of the penetration hole  303 , the relative position between the power transmission conductor  66  and the current/voltage detection printed board  4  can be substantially kept constant. 
     Like  FIG. 33 , when a cover is only provided at the upper portion of the casing, the insulator  69  may not be stably fixed. In this case, in order to stabilize the insulator  69 , a mounting part (not shown) for fixing the insulator  69  may be provided at the lower portion of the casing main body  300  (as viewed from the paper). 
       FIG. 34  is a diagram showing a case where the sizes of the power transmission conductor  66  and the insulator  69  in the current/voltage detector  3   b  of  FIG. 33  are suited to the size of the current/voltage detector  3   b.    
     Like  FIG. 33 , when the insulator  69  is fixed to the current/voltage detector  3   b , in order to improve maintenance, as shown in  FIG. 34 , the sizes of the power transmission conductor  66  and the insulator  69  may be suited to the size of the current/voltage detector  3   b , such that the power transmission conductor  66  and the insulator  69  can be removed from the current/voltage detector  3   b . With this configuration, maintenance can be improved. Though not shown in  FIG. 34 , a connection portion for connection to another conductor is provided in the power transmission conductor  66 . 
     Although a case where the power transmission conductors  66  and  68  are a cylindrical copper rod, that is, has a circular shape in section has been described in the above description, the invention is not limited thereto. For example, a conductor having an elliptical shape or a rectangular shape in section maybe used. Furthermore, although a case where the penetration hole  401  of the current/voltage detection printed board  4  has a circular shape has been described, the invention is not limited thereto. For example, an elliptical shape or a rectangular shape may be used. 
     As described above, there exist various kinds of the shield portion, the coiled wire  10 , and the ring-shaped wire  30  constituting the current/voltage detection printed board  4 . Therefore, other combinations than those described above can be made.