Abstract:
A coaxial connector ( 1 ), which is attached to a circuit board ( 2 ) having a land ( 151 ), includes a coaxial terminal ( 51 ) having a coaxial structure including a centre terminal ( 52 ) and a cylindrical outer terminal ( 61 ) surrounding the centre terminal; a housing ( 11 ) accommodating the coaxial terminal; a cylindrical contact ( 81 ) movable in an axial direction of an axis of the outer terminal and brought into contact with the land; a biasing member ( 71 ) biasing the cylindrical contact so that the cylindrical contact projects from the housing; and a rotation mechanism which rotates the cylindrical contact about the axis when the cylindrical contact is pushed into the housing against a biasing force of the biasing member. Accordingly, the coaxial connector capable of performing wiping in a terminal having the coaxial structure, such as a probe, is provided.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese Patent Application No. 2008-327309, filed on Dec. 24, 2008, the disclosure of which is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a coaxial connector. 
       DESCRIPTION OF THE RELATED ART 
       [0003]    Japanese Utility Model Application Laid-open No. 60-123666 discloses a coaxial movable contact terminal  851 , as shown in  FIG. 19 , which is used in an inspection apparatus. The coaxial movable contact terminal  851  includes a center conductor  852  and an outer conductor  861  having a plain cylindrical shape and surrounding the center conductor  852 . As shown in  FIG. 20 , the terminals  851  are held by a movable plate  802  movable relative to a target circuit board  801  on which ICs (Integrated Circuits) are mounted as targets of measurement. Further, coaxial connectors (hereinafter referred to as “coaxial plugs”)  961  are connected to one ends of the terminals  851 , respectively. Each of the coaxial plugs  961  is connected via a coaxial cable  962  to a measuring circuit board (not shown) on which a signal generator circuit, a comparator, etc. are mounted. At the time of the measurement, the movable plate  802  is moved toward the target circuit board  801  to bring the other ends of the terminals  851  into contact with the target circuit board  801 . Consequently, the coaxial plugs  961  are electrically connected to the target circuit board  801  by the terminals  851 , to thereby electrically connect the target circuit board  801  and the measuring circuit board to each other. 
         [0004]    By using the coaxial terminals  851 , a high-frequency component of a signal is hardly attenuated or reflected in the terminals. Accordingly, an input signal outputted by the signal generator circuit in the measuring circuit board is transmitted or transferred to the target circuit board  801  via the terminals  851  as maintaining its waveform satisfactorily. Further, an output signal outputted by an IC as the target of the measurement (measurement target) in the target circuit board  801  is transmitted to the measuring circuit board via the terminals  851  while maintaining its waveform satisfactorily. 
         [0005]    However, the coaxial movable contact terminals  851  of Japanese Utility Model Application Laid-open No. 60-123666 are press-fit in cavities  814  formed in the movable plate  802 ; and the movable plate  802  is moved toward the target circuit board  801  to thereby move the coaxial movable contact terminals  851  upwardly and downwardly so that the terminals  851  are brought into contact with the target circuit board  801 . As described above, the coaxial movable contact terminals  851  are merely in pressure contact with the target circuit board  801  from below. Therefore, for example, in a case that oxide film, etc. is formed on a surface of a land of the target circuit board  801 , there is a fear that the connection resistance is increased due to the oxide film, which in turn creates a possibility that high-frequency signals cannot be received in a desired waveform via the coaxial movable contact terminals  851 . 
         [0006]    Japanese Patent Application Laid-open No. 7-272810 discloses a movable contact pin device for an IC socket. An IC package is mounted on the movable contact pin device. At the time of the mounting, a contact member, of the movable contact pin device, which construct the movable contact pin device is brought into pressurized contact with a connection terminal of the IC package, and then the contact member is rotated by another twisted member constructing the movable contact pin device. In such a manner, the contact member is rotated in a state that the contact member is in contact with the connection terminal to thereby perform wiping. By doing so, it is possible to rub off or remove the oxide film, etc. from the surfaces of the connection terminal and the contact member, making it possible to suppress the increase in connection resistance. 
         [0007]    In the contact rotation mechanism of Japanese Patent Application Laid-open No. 7-272810, however, the contact member is rotated by using the another twisted constructing member which constructs the movable contact pin device. Therefore, it is necessary to arrange the another twisted constructing member at the position of the rotation axis of the contact member. Therefore, in a case that an attempt is made to rotate the outer conductor  861  in the coaxial movable contact terminal  851  disclosed in Japanese Utility Model Application Laid-open No. 60-123666, it is necessary to arrange the another twisted constructing member at a position of the rotation axis of the outer conductor  861 . In the coaxial movable contact terminal  851 , however, the center conductor  852  needs to be arranged at the center of the outer conductor  861 . Thus, in the coaxial movable contact terminal  851  disclosed in Japanese Utility Model Application Laid-open No. 60-123666, even if the attempt were made to arrange the another twisted constructing member, disclosed in Japanese Patent Application Laid-open No. 7-272810, at the position of the rotation axis of the outer conductor  861 , it is not possible to arrange the another twisted constructing member disclosed in Japanese Patent Application Laid-open No. 7-272810 at the position of the rotation axis since the center conductor  852  is already arranged at the position. As a result, in the coaxial movable contact terminal  851 , it is not possible to rotate the outer conductor  861  by using the another twisted constructing member in order to perform the wiping, and thus it is not possible to suppress the increase in connection resistance in the coaxial movable contact terminal  851 . 
       SUMMARY OF THE INVENTION 
       [0008]    An object of the present invention is to provide a coaxial connector capable of perform wiping in a terminal having coaxial structure such as a probe. 
         [0009]    According to the present invention, there is provided a coaxial connector  1  which is attached to a circuit board  2  having a land  151 , the coaxial connector  1  including: a coaxial terminal  51  which has a coaxial structure including a center terminal  52  and a cylindrical outer terminal  61  surrounding the center terminal  52 ; a housing  11  which accommodates the coaxial terminal  51 ; a cylindrical contact  81  which is movable in an axial direction of an axis of the outer terminal  61  and which is brought into contact with the land  151 ; a biasing member  71  which biases the cylindrical contact  81  so that the cylindrical contact  81  projects from the housing  11 ; and a rotation mechanism which rotates the cylindrical contact  81  about the axis when the cylindrical contact  81  is pushed into the housing  11  against a biasing force of the biasing member  71 . In the present application, the term “land” means a contact point, which is provided on the circuit board, at which the connector is brought into contact with the circuit board and which has any shape. The land may include, for example, a pad, etc. 
         [0010]    Since the cylindrical contact  81  is biased in such a manner by the biasing member so as to project from the housing  11 , the cylindrical contact  81  is first brought into contact with the land  151  of the circuit board  2  when the coaxial connector  1  is attached to the circuit board  2 . Afterwards, the cylindrical contact  81  is pushed or pressed into the housing  11 , whereby the coaxial connector  1  is attached to the circuit board  2 . Then, during a period of time until the coaxial connector  1  is attached to the circuit board  2 , the cylindrical contact  81  brought into contact with the land  151  of the circuit board  2  is rotated about or with respect to the axis by the rotation mechanism. 
         [0011]    Accordingly, since the cylindrical contact  81  is rotated in a state that the cylindrical contact  81  is in contact with the land  151  of the circuit board  2 , it is possible to rub the cylindrical contact  81  and the land  151  against each other to thereby wiping the cylindrical contact  81  and the land  151 . Further, with this wiping, it is possible to rub off or remove an oxide film from a contact portion, of the cylindrical contact  81 , which is brought into contact with the land  151  and the surface of the land  151  of the circuit board  2  and to remove dust or dirt which has been caught between the cylindrical contact  81  and the land  151 , thereby making it possible to suppress the increase in contact resistance between the outer terminal  61  and the circuit board  2 . In the present application, it is possible to perform the wiping in such a manner in the terminal having the coaxial structure. 
         [0012]    Further, the biasing member makes the biasing force constantly act on the cylindrical contact  81  so that the cylindrical contact  81  projects from the housing  11 . Therefore, the cylindrical contact  81  rotates (is rotated) in a state that the cylindrical contact  81  is in pressure contact with the land  151  due to the biasing force. Therefore, even when the housing  11  is strongly pressed against the circuit board  2 , the cylindrical contact  81  is not brought into pressure contact against the land  151  with a force which is greater than the biasing force, thereby making it possible to prevent any damage of the cylindrical contact  81  and/or the land  151  which would be otherwise caused if the cylindrical contact  81  were brought into pressure contact against the circuit board with an excessively strong force. In addition, the biasing member continuously makes the cylindrical contact  81  brought into pressure contact with the land  151  even after the coaxial connector  1  is attached to the circuit board  2 . Therefore, it is possible to maintain a state that the contact resistance is lowered between the cylindrical contact  81  and the land  151 . 
         [0013]    The biasing member may be a member which is elastically deformable such as, for example, a coil spring, a leaf spring or the like. In a case that the biasing member is a coil spring  71  which is arranged coaxially with the coaxial terminal  51 , the rotation mechanism which rotates the cylindrical contact  81  may include a projection  84  which is formed in the cylindrical contact  81  and with which one end of the coil spring  71  is brought into contact; and the cylindrical contact  81  may be rotated when the coil spring  71  is expanded or compressed to pull or push the projection  84 . 
         [0014]    In such a manner, by expanding or compressing the coil spring  71  to thereby pull or push the projection  84  formed in the cylindrical contact  81 , it is possible to use the coil spring  71  as the biasing member also in the rotation mechanism rotating the cylindrical contact  81 . This makes it possible to reduce the number of components or parts arranged around the coaxial terminal  51  and to simplify the structure of the terminal. In addition, the coil spring  71  can be arranged coaxially with the coaxial terminal  51  in a state that, for example, the coil spring  71  is wound around the outer terminal  61 . As a result, it is possible to reduce an area or range occupied by each of the coaxial terminals  51  in the housing  11 , thereby making it possible to arrange, in the housing  11 , a plurality of pieces of the coaxial terminal  51  at a pitch that is same as that of conventional coaxial terminals which is not provided with the coil spring  71 , etc. 
         [0015]    Further, in the present invention, the coil spring  71  may be brought into contact with the projection  84  in a state that the coil spring  71  is compressed. By bringing the coil spring  71  in the compressed state into contact with the projection  84 , it is possible to push and rotate the cylindrical contact  81  in assured manner. Further, when the cylindrical contact  81  is pushed into the housing  11  to further compress the coil spring  71 , the force pushing (pressing) the cylindrical contact  81  becomes greater, thereby making it possible to rotate the cylindrical contact  81  assuredly even if the cylindrical contact  81  is hooked to or caught by the land  151 . On the other hand, in a case that the projection  84  is pulled by the expanded coil spring  71 , the cylindrical contact  81  is pushed into the housing  11  to thereby suppress the expansion of the coil spring  71 , thus cancelling the force pulling the projection  84 . 
         [0016]    Furthermore, in the present invention, the rotating mechanism which rotates the cylindrical contact  81  may further include: a fix portion  26  which is formed in the coaxial terminal  51  or the housing  11 , and a movable portion  85  which is formed in the cylindrical contact  81  and which is engaged with the fix portion  26 ; and the cylindrical contact  81  may start to rotate when the cylindrical contact  81  is pushed into the housing  11  to disengage the movable portion  85  from the fix portion  26 . 
         [0017]    In this manner, when the cylindrical contact  81  is pushed into the housing  11  to thereby disengage the movable portion  85  from the fix portion  26  (release the engagement between the fix portion  26  and the movable portion  85 ), the cylindrical contact  81  starts to rotate. Accordingly, it is possible to prevent the cylindrical contact  81  from rotating when the cylindrical contact  81  is not pushed into the housing  11 , and to make the cylindrical contact  81  rotate when the cylindrical contact  81  is pushed into the housing  11  against the biasing force of the biasing member. 
         [0018]    In particular, in a case that the coil spring  71  as the biasing member is a mechanism which rotates the cylindrical contact  81  when the coil spring  71  is brought into contact with the projection  84  formed in the cylindrical contact  81 , the coil spring  71  is in a compressed state when the cylindrical contact  81  is pushed into the housing  11  to thereby disengage the movable portion  85  from the fix portion  26 . Therefore, when the cylindrical contact  81  starts rotating, the coil spring  71  in the compressed state is brought into contact with the projection  84 . Therefore, even if the cylindrical contact  81  is caught by or hooked to the land  151  before the cylindrical contact  81  starts rotating, it is possible to surely rotate the cylindrical contact  81  by the force releasing the compression of the spring force  71 . 
         [0019]    Moreover, in the present invention, the rotation mechanism may further include a restricting portion  27  which is formed in the coaxial terminal  51  or the housing  11  and which is engaged with the movable portion  85 , disengaged from the fix portion  26 , to restrict movement of the movable portion  85 . By providing, in such a manner, the restricting portion  27  which is engaged with the movable portion  85  disengaged from the fix portion  26 , it is possible to restrict (regulate) a range in which the cylindrical contact  81  is rotated to a range in which the movable portion  85  is moved from the fix portion  26  to the restricting portion  27 . That is, by limiting a rotation amount of the cylindrical contact  81 , it is possible to restrict a range in which the wiping is performed on the land  151  (circuit board  2 ). 
         [0020]    Further, in the present invention, the cylindrical contact  81  may have a plurality of projecting contact points  83  which are arranged on the cylindrical contact  81  at rotationally symmetric positions of a cylindrical shape of the cylindrical contact to project from the cylindrical contact and which are brought into contact with the land  151 . 
         [0000]    In this case, it is possible to bring the cylindrical contact  81  into contact with the land  151  at the plurality of projecting contact points  83  in assured manner, and to wipe the land  151  assuredly. Further, it is enough that the land  151  is formed on the circuit board  2  at a range in which the plurality of projecting contact points  83  perform the wiping (range in which the plurality of projecting contact points  83  are brought into contact with the land  151 ). On the other hand, in a case that the plurality of projecting contact points  83  is not provided, the contact range on the circuit board  2  which is brought into contact with the cylindrical contact  81  cannot be determined, which in turn necessitate forming, for example, a doughnut-shaped land corresponding to the cylindrical shape of the cylindrical contact  81 , or creating possibility such that the cylindrical contact  81  erroneously wipes a portion, of the circuit board  2 , which is different from the land  151 . 
         [0021]    As described above, in the coaxial connector of the present invention, it is possible to perform the wiping in the terminal having the coaxial structure such as a probe. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view of a connector of an embodiment of the present invention and a circuit board; 
           [0023]      FIG. 2  is a partial exploded perspective view of the connector shown in  FIG. 1 ; 
           [0024]      FIG. 3  is a partial exploded perspective view of a housing and a coaxial terminal in  FIG. 2 ; 
           [0025]      FIG. 4  is a partial exploded perspective view of a portion of the coaxial terminal shown in  FIG. 3 ; 
           [0026]      FIG. 5  is a view showing a partial assembly state of the connector shown in  FIG. 1 , with a partial cutout; 
           [0027]      FIG. 6  is a partial view showing further partial assembly state of the connector shown in  FIG. 1 , with a partial cutout; 
           [0028]      FIG. 7  is a partial view showing still further partial assembly state of the connector shown in  FIG. 1 , with a partial cutout; 
           [0029]      FIG. 8  is a partial view showing further assembly state of the connector shown in  FIG. 1 , with a partial cutout; 
           [0030]      FIGS. 9A to 9D  are explanatory views each showing a state when the connector shown in  FIG. 1  is attached to the circuit board; 
           [0031]      FIG. 10  is a partial perspective view of the connector corresponding to  FIG. 9A , with partial cutout; 
           [0032]      FIG. 11  is a partial perspective view of the connector corresponding to  FIG. 9B , with partial cutout; 
           [0033]      FIG. 12  is a partial perspective view of the connector corresponding to  FIG. 9C , with partial cutout; 
           [0034]      FIG. 13  is a partial perspective view of the connector corresponding to  FIG. 9D , with partial cutout; 
           [0035]      FIG. 14  is a partial bottom view of the connector in the state shown in  FIG. 9A ; 
           [0036]      FIG. 15  is a partial bottom view of the connector in the state shown in  FIG. 9C ; 
           [0037]      FIG. 16  is a perspective view of a holder which is to be connected to the connector in  FIG. 1 ; 
           [0038]      FIG. 17  is a vertical sectional view showing a state that the holder in  FIG. 16  is connected to the connector in the state shown in  FIG. 9D ; 
           [0039]      FIG. 18  is a partial exploded perspective view of a housing and a coaxial terminal of a connector of a modification of the present invention; 
           [0040]      FIG. 19  is a cross-sectional view showing a conventional coaxial movable contact terminal; and 
           [0041]      FIG. 20  is a view showing the coaxial movable contact terminal shown in  FIG. 19  is in use. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    In the following, an explanation will be given about an embodiment of a coaxial connector of the present invention with reference to the drawings. It should be noted that the embodiment described below is an example of a preferred embodiment of the present invention and is not intended to limit the present invention. 
         [0043]      FIG. 1  is a perspective view of a connector  1  of the embodiment seen from obliquely above.  FIG. 1  also shows a circuit board  2  to which the connector  1  is to be attached. The connector  1  has a housing  11  which is formed in a cubic shape by using an insulating material such as resin; a plurality of cavities  14  which penetrate through the housing  11  in an up and down direction; and a plurality of coaxial terminals  51  each of which has a coaxial structure including a center terminal  52  and an outer terminal  61  and which are accommodated in the cavities  14 , respectively. 
         [0044]    As shown in  FIG. 1 , a plurality of lands  151  are formed in the circuit board  2 . Electric wirings such as through holes (not shown) are connected to the lands  151 . 
         [0045]    As shown in  FIGS. 9D and 17  (which will be described later), the connector  1  is attached to the circuit board  2  at a lower surface  12   a  of the housing  11 . Further, in each of the coaxial terminals  51 , the center terminal  52  and the outer terminal  61  which project downward from the housing  11  are brought into contact with and electrically connected to three pieces of the land  151 , the lands  151  being aligned on the circuit board  2  such that land rows are each formed of three pieces of the land  151 . 
         [0046]      FIG. 2  is an exploded perspective view of the housing  11 . The housing  11  is vertically divided into two parts by a plane extending in parallel to the circuit board  2  and thereby includes a lower housing  12  and an upper housing  13 . The lower housing  12  is positioned under the upper housing  13  in  FIG. 1  and is directly attached to the circuit board  2 ; and a lower surface  23  of the upper housing  13  and an upper surface  22  of the lower housing  12  are in contact with each other. Further, the plurality of cavities  14  are formed in the housing  11 . Each of the cavities  14  is constructed of a lower cavity  24  formed in the lower housing  12  and an upper cavity  25  formed in the upper housing  13 . 
         [0047]    Furthermore, in the lower housing  12 , two pieces of an anchor press-fit slit  19  and two pieces of a movable piece-slit  28  are formed to communicate with each of the lower cavities  24 . Moreover, as shown in  FIG. 5  (which will be described later), a lower end portion of each of the movable piece-slits  28  functions as a restricting recess portion  27 ; and a fix recess portion  26   a  is defined by a groove extending downwardly from the restricting recess portion  27 . The two anchor press-fit slits  19  the two movable piece-slits  28  are both formed in the lower housing  12  such that the two anchor press-fit slits  19  are arranged to be rotationally symmetric with respect to the lower cavity  24  having columnar shape (that is, arranged at an interval of 180 degrees), and that the two movable piece-slits  28  are arranged to be rotationally symmetric with respect to the lower cavity  24  having columnar shape (that is, arranged at an interval of 180 degrees). 
         [0048]      FIGS. 3 and 4  are each an exploded view of the coaxial terminal  51  which is accommodated in the cavity  14 . 
         [0049]    Each of the coaxial terminals  51  includes the center terminal  52 , the outer terminal  61 , and an insulator  41  via which the outer terminal  61  holds the center terminal  52  in an insulated state; and each of the coaxial terminals  51  is accommodated in one of the cavities  14  formed in the housing  11  as shown in  FIG. 2 . The center terminal  52  is mated with an axial terminal  162  of a coaxial plug  161  as shown in  FIG. 16  (to be described later); and the outer terminal  61  is mated with a surrounding terminal  163  of the coaxial plug  161 . 
         [0050]    As shown in  FIG. 4 , the center terminal  52  includes a center conductor  53 , a center coil spring (not shown), and a shaft-shaped contact  59  each of which is formed by using a conductive material. The center conductor  53  has a substantially shaft shape and has, on the upper portion thereof, a mating portion  55  holding or sandwiching the axial terminal  162  of the coaxial plug  161 . Further, a center hole  56  is formed in the lower surface of the center conductor  53  having the shaft shape; and the center coil spring and one end of the shaft-shaped contact  59  are inserted in the center hole  56 . 
         [0051]    As shown in  FIG. 4 , the insulator  41  has a cylindrical shape and includes a large-diameter portion and a small-diameter portion which are coaxial. A center hole  42  is formed at the center of the cylindrical insulator  41 , and the center terminal  52  is inserted in the center hole  42 . 
         [0052]    As shown in  FIGS. 3 and 4 , the outer terminal  61  includes an outer conductor  62 , an outer coil spring  71  and a cylindrical contact  81  each of which is formed by using a conductive material such as a metal plate. The outer conductor  62  has a substantially cylindrical shape as a whole and includes a body portion  64  having a pair of anchors  63  projecting or protruding from the surface (outer surface) of the body portion  64 ; a mating portion  66  formed above the body portion  64 ; and a thin cylinder portion  67  which is formed below the body portion  64 . The mating portion  66  is constructed of four leaf springs  65  which hold the surrounding terminal  163  of the coaxial plug  161 . The thin cylinder portion  67  is formed to be thinner than the body portion  64  and is inserted in the outer coil spring  71  and the cylindrical contact  81 . 
         [0053]    As shown in  FIG. 3 , the cylindrical contact  81  is formed to have a cylindrical shape into which the thin cylinder portion  67  can be inserted and is movable in the axial direction of the outer terminal  61 . Further, a projection  84 , two movable pieces  85 , and two projecting contact points  83  are formed in the cylindrical contact  81 . The projection  84  projects from an upper edge portion of the cylinder of the cylindrical contact  81  such that a stepped shaped-portion is formed on the upper edge portion of the cylindrical shape of the cylindrical contact  81 . Each of the movable pieces  85  projects from the outer surface of the upper portion of the cylindrical contact  81  having the cylindrical shape. Each of the projecting contact points  83  projects from the lower end of the cylindrical contact  81  having the cylindrical shape. Note that the two movable pieces  85  and the two projecting contact points  83  are both formed on the outer surface of the cylindrical contact  81  having the cylindrical shape, such that the two movable pieces  85  are arranged to be rotationally symmetric with respect to each other (that is, arranged at an interval of 180 degrees) and that the two projecting contact points  83  are arranged to be rotationally symmetric with respect to each other (that is, arranged at an interval of 180 degrees). 
         [0054]    Upon assembling the coaxial terminal  51 , the center terminal  52  is first inserted in the center hole  42  of the insulator  41 , and then the insulator  41  is inserted in the outer conductor  62 , whereby the center terminal  52  and the insulator  41  are assembled in the outer conductor  62  as shown in  FIG. 3 . In the following explanation, the outer terminal  62 , in which the insulator  41  and the center terminal  52  are assembled, is referred to as “sub-assembly”. 
         [0055]    Next, assembly processes of the connector  1  as shown in  FIG. 1  will be explained with reference to  FIGS. 5 to 8 . First, as shown in  FIG. 5 , the cylindrical contact  81  is inserted in the lower cavity  24 . At this time, the movable pieces  85  of the cylindrical contact  81  are inserted in the movable piece-slits  28  of the lower housing  12 , respectively. With this, the movable pieces  85  are accommodated in the fix recess portions  26  each forming the lower end portion of one of the movable piece-slits  28 . 
         [0056]    Next, as shown in  FIG. 6 , the outer coil spring  71  is inserted in the lower cavity  24 . With this, the outer coil spring  71  is disposed above the cylindrical contact  81  in the lower cavity  24 . Further, a lower end of the winding forming the outer coil spring  71  is capable of abutting on the projection  84  of the cylindrical contact  81 . 
         [0057]    Next, as shown in  FIG. 7 , the sub-assembly is inserted in the lower cavity  24 . At this time, the pair of anchors  63  are press-fit in the pair of anchor press-fit slits  19  formed in the lower housing  12 . With this, the sub-assembly is fixed to the lower housing  12 . Further, the center terminal  52  and the outer terminal  61  of the coaxial terminal  51  are coaxially structured. 
         [0058]    In the state that the pair of anchors  63  are press-fit in the anchor press-fit slits  19 , the outer coil spring  71  is sandwiched between the outer conductor  62  and the cylindrical contact  81  to be compressed. Therefore, the lower end of the winding of the outer coil spring  71  is pressed against the projection  84  of the cylindrical contact  81 ; and the other end, of the winding, which is the upper end of the coil spring  71  is pressed against a fix piece  69  of the outer conductor  62 . Note that a pressed state same as that described above may be provided by inserting the sub-assembly in the lower cavity  24  while twisting the sub-assembly. 
         [0059]    Since the outer conductor  62  is in a state that the pair of anchors  63  are press-fit in the anchor press-fit slits  19  to thereby prevent the outer conductor  62  from rotating in the lower cavity  24  (cavity  14 ), the compressed outer coil spring  71  presses or pushes the projection  84  of the cylindrical contact  81  and thus the movable pieces  85  inserted in the fix recess portions  26  are positioned in the fix recess portions  26 . 
         [0060]    Afterwards, as shown in  FIG. 8 , the upper housing  13  is stacked or placed on the lower housing  12 . With this, the coaxial terminal  51  is accommodated in the cavity  14  constructed of the upper cavity  25  and the lower cavity  24 , thereby completing the assembly of the connector  1  as shown in  FIG. 1 . At this time, the outer conductor  62  and the cylindrical contact  81  are always electrically connected by the outer coil spring  71  which is in pressurized contact with the outer conductor  62  and the cylindrical contact  81 . 
         [0061]    Further, in the state that the coaxial terminal  51  is accommodated in the cavity  14 , the lower end of the cylindrical contact  81  projects from the lower surface  12   a  of the lower housing  12  due to the downward biasing force of the outer coil spring  71 . The two projecting contact points  83 , of the cylindrical contact  81  projecting from the lower surface  12   a  of the lower housing  12 , are brought into contact with the lands  151  of the circuit board  2  shown in  FIG. 1 . The cylindrical contact  81  is movable in the axial direction of the thin cylinder portion  67  (outer terminal  61 ), and by this movement of the cylindrical contact  81 , a projection amount by which the cylindrical contact  81  projects from the lower surface  12   a  of the lower housing  12  can be changed or made variable. Similarly, the lower end of the shaft-shaped contact  59  also projects from the lower surface  12   a  of the lower housing  12 , due to the downward biasing force of the center coil spring. The shaft-shaped contact  59  projecting from the lower housing  12  is brought into contact with the land  151  of the circuit board  2  shown in  FIG. 1 . Further, the shaft-shaped contact  59  is also movable in the axial direction of the center terminal  52 ; and by this movement of the shaft-shaped contact  59 , a projection amount by which the shaft-shaped contact  59  projects from the lower surface  12   a  of the lower housing  12  can be changed or made variable. 
         [0062]    Next, an explanation will be given about a method of attaching the connector  1  shown in  FIG. 1  to the circuit board  2 , with reference to  FIGS. 9 to 15 . Note that the states shown in  FIGS. 10 to 13  respectively are in one-to-one correspondence to the states shown in  FIGS. 9A to 9D . Further, the bottom view shown in  FIG. 14  corresponds to the state shown in  FIG. 9A  and the bottom view shown in  FIG. 15  corresponds to the state shown in  FIG. 9C . 
         [0063]    First, as shown in  FIG. 9A , the pair of projecting contact points  83  of the cylindrical contact  81  and the shaft-shaped contact  59  are brought into contact with the lands  151  of the circuit board  2 . At this time, as shown in  FIG. 10 , the movable pieces  85  of the cylindrical contact  81  are engaged with the fix recess portions  26  of the housing  11 . 
         [0064]    Next, the housing  11  is pressed against the circuit board  2 . With this, as shown in  FIGS. 9B to 9D , the cylindrical contact  81  and the shaft-shaped contact  59  are pushed into the housing  11 . Then, as shown in  FIG. 9D , the bottom surface  12   a  of the housing  11  is brought into contact with the circuit board  2 , thereby attaching the connector  1  to the circuit board  2 . 
         [0065]    By pressing the housing  11  against the circuit board  2  in such a manner, the cylindrical contact  81  is pushed into the housing  11  against the biasing force of the outer coil spring  71  while being kept in pressure contact with the lands  151 . Further, the shaft-shaped contact  59  pressed downward by the center coil spring (not shown) is also pushed into the housing  11  against the biasing force of the center coil spring while being kept in pressure contact with the land  151 . 
         [0066]    By pushing the cylindrical contact  81  into the housing  11  in such a manner, the movable pieces  85  inserted in the movable piece-slits  28  move upward in the movable piece-slits  28  as shown in  FIGS. 10 to 13 . Specifically, when the movable pieces  85  engaged with the fix recess portions  26  as shown in  FIG. 10  start to move upwardly, the movable pieces  85  are disengaged or released from the fixed recess portions as shown in  FIG. 11  and the movable pieces  85  are rotated together with the cylindrical contact  81  by the force of the outer coil spring  71  attempting to expand because the outer coil spring  71  is in the compressed state. Then, as shown in  FIG. 12 , the movable pieces  85  are engaged with the restricting recess portions  27 ; and as shown in  FIG. 13 , the movable pieces  85  move further upwardly in the movable piece-slits  28  while being kept engaged with the restricting recess portions  27 . Note that as shown  FIGS. 14 and 15  which are bottom views, the cylindrical contact  81  is rotated clockwise. 
         [0067]    Further, the cylindrical contact  81  is rotated by the force of the outer coil spring  71  during a period of time during which the state shown in  FIG. 11  is changed to the state shown in  FIG. 12 . Therefore, the projecting contact points  83  are moved on the lands  151  of the circuit board  2  while being kept in contact with the lands  151  as shown in  FIGS. 9B and 9C . Further, also during this period, the downward force by the compressed outer coil spring  71  acts on the cylindrical contact  81 . Therefore, the projecting contact points  83  are rubbed against the lands  151 . Consequently, it is possible to rub off or remove an oxide film from the surfaces of the pair of projecting contact points  83  and of the lands  151  and to remove dust or dirt which has been caught between the projecting contact points  83  and the lands  151 . 
         [0068]      FIG. 16  is a perspective view showing a plug  3  which is to be attached to the connector  1  of this embodiment. The plug  3  includes a holder  121 . In the holder  121 , a plurality of cavities  123  are formed in arrangement corresponding to that of the coaxial probes  51  of the connector  1 . In the cavities  123 , the coaxial plugs  161  are inserted respectively. Each of the coaxial plugs  161  includes the axial terminal  162  and the surrounding terminal  163  which surrounds the axial terminal  162  and which is arranged coaxial with the axial terminal  162 . 
         [0069]      FIG. 17  is a view showing a state that the plug  3  is mated with the connector  1  which is attached to the circuit board  2 . In this mated state, each of the coaxial plugs  161  of the plug  3  is mated with one of the coaxial probes  51  of the connector  1 . Specifically, the axial terminal  162  of each of the coaxial plugs  161  is pushed into the mating portion  55  of one of the center conductors  53 . With this, the axial terminal  162  of each of the coaxial plugs  161  is electrically and securely connected to the land  151  of the circuit board  2  via the center terminal  52 . Further, the surrounding terminal  163  of each of the coaxial plugs  161  is inserted into a plurality of leaf springs  65  of the mating portion  55  of one of the outer conductors  62  to thereby push the leaf springs  65 . With this, the surrounding terminal  163  of the coaxial plug  161  is electrically and securely connected to the land  151  of the circuit board  2  via the outer terminal  61 . 
         [0070]    As described above, by pressing the housing  11  in the contact state in  FIG. 9A  against the circuit board  2 , the cylindrical contacts  81  is rotated while being pushed into the housing  11  as shown in  FIGS. 10 to 13  and the connector  1  of this embodiment is attached to the circuit board  2  as shown in  FIG. 9D . Therefore, the pair of projecting contact points  83  brought into contact with the lands  151  of the circuit board  2  in  FIG. 9A  are rotated on the lands  151  to rub against the lands  151  during a period of time during which the state shown in  FIG. 9B  is changed to the state shown in  FIG. 9C . With this, it is possible to perform the wiping of the pair of projecting contact points  83  and the lands  151 . 
         [0071]    As described above, in the connector  1  of this embodiment, it is possible to perform the wiping upon attaching the connector  1  to the circuit board  2 , even though the terminals of the connector  1  are the coaxial terminals  51 . Further, by this wiping, it is possible to rub off or remove the oxide film from the surfaces of the pairs of projecting contact points  83  and the lands  151  and to remove dust caught therebetween, thereby making it possible to prevent the increase in contact resistance between the coaxial terminals  51  and the lands  151 . 
         [0072]    In addition, since each of the cylindrical contacts  81  is brought into pressure contact with the lands  151  by the outer coil spring  71 , it is possible to bring the pairs of projecting contact points  83  into contact with the lands  151  before the housing  11  is attached to the circuit board  2 , to bring the pairs of projecting contact points  83  into pressure contact with the lands  151  by a desired biasing force at the time of the wiping, and to reduce the contact resistance between the pairs of projecting contact points  83  and the lands  151  in the state that the housing  11  is attached to the circuit board  2 . 
         [0073]    Further, the pair of projecting contact points  83  are arranged on the cylindrical contact  81  at rotationally symmetric positions of the cylindrical shape of the cylindrical contact  81 . With this, it is possible to limit or regulate a contact portion, at which the cylindrical contact  81  and the lands  151  are brought into contact with each other, to the pair of projecting contact points  83  and to assuredly bring the cylindrical contact  81  into contact with the lands  151 . Further, it is sufficient that the lands  151  are formed on the circuit board  2  at a range in which the pairs of projecting contact points  83  perform the wiping, thereby eliminating any need to form the land  151  in a doughnut shape or the like corresponding to the cylindrical shape of the cylindrical contact  81 . Furthermore, it is possible to prevent the cylindrical contacts  81  from erroneously wiping portions other than the lands  151  of the circuit board  2 . 
         [0074]    Since the terminals of the connector  1  are the coaxial terminals  51 , it is possible to prevent crosstalk among the plurality of coaxial terminals  51 . As a result, in the connector  1 , it is possible to obtain the performance sufficient for transmitting or transferring high-frequency component of the signal. Accordingly, the connector  1  can be used, in an IC inspection apparatus or the like, for connecting a target circuit board having an IC as the measurement target mounted thereon to a measuring circuit board having a signal generator circuit, a comparator, etc. mounted thereon, with the coaxial cables and without any soldering. 
         [0075]    Note that in this embodiment, although the pair of projecting contact points  83  are formed in each of the cylindrical contacts  81 , it is allowable that the number of the projecting contact points  83  is one or not less than three. In a case that the plurality of projecting contact points  83  are formed in the cylindrical contact  81 , the plurality of projecting contact points  83  may be provided on the cylindrical contact  81  having the cylindrical shape, in arrangement other than the rotational symmetry. 
         [0076]    Further, in this embodiment, the projection  84  of the cylindrical contact  81  is pushed by the compressed outer coil spring  71 . However, the cylindrical contact  81  may be rotated by pulling the projection  84  by the expanded outer coil spring  71 . 
         [0077]    Further, in this embodiment, the fix recess portions  26  and the restricting recess portions  27  which are engaged with the movable pieces  85  of the cylindrical contact  81  are formed in the housing  11 . However, at least either one of the fix recess portions  26  and the restricting recess portions  27  may be formed in the coaxial terminal  51  at a portion which is different from the cylindrical contact  81  (for example, at the outer conductor  62  or the like). Further, at least one of the fix recess portion  26  and the restricting recess portion  27  may be a fix projection. 
         [0078]      FIG. 18  shows a partial exploded perspective view of a connector  1  according to a modification of the present invention. The connector  1  includes an outer terminal  61  which has an outer conductor  62 , an outer coil spring  71 , a cylindrical contact  81 , and a cover  225 . The cover  225  has a cylindrical shape of which inside diameter is greater than the outside diameter of each of the spring  71  and the cylindrical contact  81 , and the cover  225  can accommodate, in an assembled state, the spring  71  and an upper portion of the cylindrical contact  81  inside the cover  225 . Further, the cover  225  is arranged so that a slit  228 , which is formed in the cover  225  at the upper edge of the cylindrical shape of the cover  225 , is engaged with a fix piece, thereby preventing the cover  225  from rotating. Furthermore, the cover  225  is provided with fix recess portions  226  and restricting recess portions  227  which are formed in the cover  225  at the lower edge of the cylindrical shape of the cover  225 , and which accommodate movable pieces  85  of the cylindrical contact  81  therein. With this structure, in a state that the cylindrical contact  81  projects from a lower surface  12   a  of a housing  11 , the movable pieces  85  abut on the fix recess portions  226  and thus the cylindrical contact  81  does not rotate. Upon attaching the connector  1  to the circuit board  2 , the cylindrical contact  81  is pushed into the housing  11 , which results in the movable pieces  85  moving from the fix recess portions  226  to the restricting recess portions  227 , thereby rotating the cylindrical contact  81  by the spring force of the outer coil spring  71 . 
         [0079]    Further, in this embodiment, the outer coil spring  71  is used to generate the force which acts on the cylindrical contact  81  such that the cylindrical contact  81  is projected from the housing  11 . Alternatively, for example, the biasing force may be generated by using a leaf spring or the like to act on the cylindrical contact  81 . Furthermore, the leaf spring may be formed as a leaf spring structure as a part of the housing  11 . 
         [0080]    The coaxial connector of the present invention can perform the wiping by rotating the cylindrical contacts brought into contact with the lands of the circuit board, upon attaching the coaxial connector to the circuit board. Therefore, it is possible to electrically connect the cylindrical contacts and the lands of the circuit board with a low contact resistance. Accordingly, the coaxial connector of the present invention can be used, for example in an IC inspection apparatus, etc., for connecting a target circuit board having an IC as the measurement target mounted thereon to a measuring circuit board having a signal generator circuit, a comparator, etc. mounted thereon, with the coaxial cable.