Patent Publication Number: US-10770838-B2

Title: Connector

Description:
BACKGROUND 
     Field of the Invention 
     The invention relates to a connector. 
     Related Art 
     Japanese Unexamined Patent Publication No. 2012-129103 discloses a connector that has a male inner conductor mounted in a male dielectric and a female inner conductor mounted in a female dielectric. The male and female inner conductors are connected be fitting the male and female dielectrics together. 
     A connector of this type also may have a female dielectric with plural conductor accommodation chambers partitioned by separation walls and female inner conductors are accommodated individually into the conductor accommodation chambers. A connector of this type that is applied to a communication circuit preferably forms the female dielectric from a synthetic resin material having a low dielectric constant to guarantee communication performance. However, the synthetic resin material having a low dielectric constant is relatively low in strength. Thus, when elongated tabs on tips of male inner conductors interfere with the front surface of the female dielectric in the process of fitting both male and female dielectrics, the tabs may be pierced into the front surface of the female dielectric. 
     The invention was completed on the basis of the above situation and aims to combine an improvement of communication performance and a reliability improvement of a connecting operation. 
     SUMMARY 
     The invention is directed to a connector with a dielectric including conductor accommodation chambers laterally partitioned by a separation wall portion, and inner conductors are accommodated individually in the conductor accommodation chambers. The dielectric has a body made of synthetic resin. The body is formed with the separation wall portion and the conductor accommodation chambers. The dielectric also has a front wall made of synthetic resin and mounted on a front end part of the body to close front openings of the conductor accommodation chambers. Tab insertion openings are formed in the front wall to allow tabs of mating inner conductors to be inserted into the conductor accommodation chambers from the front of the dielectric. The separation wall portion is made of a material having a lower dielectric constant than the front wall, and the front wall is made of a material having a higher mechanical strength than the separation wall portion. 
     The separation wall portion is interposed between the inner conductors and is made of the material having a relatively low dielectric constant. Thus, the communication performance of electrical signals passing through the inner conductors is guaranteed. Further, the front wall is made of the material having a higher mechanical strength than the separation wall portion. Thus, even if the tabs of the mating inner conductors interfere with the front wall, there is no possibility that the tabs will pierce the front wall. 
     The dielectric may include a holding member and a lid. The holding member may be formed with the separation wall portion and grooves constituting the conductor accommodation chambers. The lid is mounted on the holding member to close openings of the grooves. According to this configuration, the inner conductors need not be inserted into the conductor accommodation chambers from behind the dielectric, and untwisted lengths of wires can be shortened when the wires connected to rear end parts of the inner conductors constitute a twisted pair cable. 
     The front wall may be formed with a positioning portion capable of positioning front end parts of the inner conductors. According to this configuration, the inner conductors can be accommodated into the grooves by one action by integrating the inner conductors with the front wall with the inner conductors positioned by the positioning portion. 
     The front wall and the holding member may be formed with fitting portions for holding the front wall member and the holding member in an assembled state by being fit to each other. The front wall may be formed with a pressing portion for holding the lid in a state assembled with the holding member by being held in contact with the lid with the front wall assembled with the holding member. According to this configuration, the lid and the holding member reliably are held in the assembled state. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view of a connector of a first embodiment. 
         FIG. 2  is a section along A-A of  FIG. 1 . 
         FIG. 3  is a section along B-B of  FIG. 1 . 
         FIG. 4  is a plan view in a state where two inner conductors are positioned in a front wall member. 
         FIG. 5  is a perspective view of a holding member. 
         FIG. 6  is a bottom view of the holding member. 
         FIG. 7  is a perspective view of a lid member. 
         FIG. 8  is a perspective view of the front wall member. 
         FIG. 9  is a back view of the front wall member. 
         FIG. 10  is a side view of the front wall member. 
         FIG. 11  is a front view of a connector of a second embodiment. 
         FIG. 12  is a section along C-C of  FIG. 11 . 
         FIG. 13  is a section along D-D of  FIG. 11 . 
         FIG. 14  is a perspective view of a holding member. 
         FIG. 15  is a bottom view of the holding member. 
         FIG. 16  is a perspective view of a lid member. 
         FIG. 17  is a bottom view of the lid member. 
         FIG. 18  is a perspective view of a front wall member. 
         FIG. 19  is a back view of the front wall member. 
         FIG. 20  is a side view of the front wall member. 
         FIG. 21  is a plan view of the front wall member. 
     
    
    
     DETAILED DESCRIPTION 
     A first embodiment of the invention is described with reference to  FIGS. 1 to 10 . Note that, in the following description, a left side in  FIGS. 2 to 7  is defined as a front side concerning a front-rear direction. Upper and lower sides shown in  FIGS. 1, 2, 5 and 7 to 10  are directly defined as upper and lower sides concerning a vertical direction. 
     A connector  1  of the first embodiment includes a dielectric  10  made of synthetic resin, inner conductors  36  and a housing  44  made of synthetic resin. The dielectric  10  includes a body  11  internally formed with left and right conductor accommodation chambers  17  and a front wall  28  to be assembled with a front part of the body  11 . The body  11  is configured by assembling a holding member  12  and a lid  24 . 
     As shown in  FIGS. 5 and 6 , the holding member  12  is long and narrow in the front-rear direction. The holding member  12  includes an upper wall  13  long in the front-rear direction, two side walls  14  extending down substantially at right angles from left and right sides of the upper wall  13  over the entire lengths thereof, and a separation wall  15  extending down from a center of the upper wall  13  in a lateral direction (width direction) substantially at a right angle over the entire length thereof. 
     Spaces enclosed by the upper wall  13  and the side walls  14  of the holding member  12  serve grooves  16  laterally partitioned by the separation wall  15 . Each groove  16  constitutes the conductor accommodation chamber  17 . Each groove  16  is elongated in the front-rear direction and is open in the lower surface of the holding member  12  over the entire length thereof. A retaining recess  18  is formed in the inner upper surface of each groove  16 . The front end of each groove  16  is open in the front surface of the holding member  12 . A front part of each groove  16  is formed with an escaping recess  19  formed by partially cutting the upper wall  13 , the side wall  14  and the separation wall  15  and is open in the front end surface of the holding member  12 . The rear end of the groove  16  is open in the rear surface of the holding member  12 . 
     Two vertically spaced fitting holes  20  are formed on the front end surface of each of the left and right side walls  14 . Two front lock projections  21 F are formed on front end parts of outer side surfaces of the left and right side walls  14 , and two rear lock projections  21 R are formed on rear end parts of the outer side surfaces of the left and right side walls  14 . Further, positioning recesses  22  are disposed between the front and rear lock projections  21 F and  21 R are formed respectively in the outer surfaces of the both left and right side walls  14 . A locking projection  23  is formed on an outer surface (upper surface) of the upper wall  13 . 
     As shown in  FIG. 7 , the lid  24  is long and narrow in the front-rear direction. The lid  24  is a single component including a lower wall  25  long in the front-rear direction, two front resilient lock pieces  26 F extending up substantially at a right angle from front end parts of both left and right side edges of the lower wall  25  and two rear resilient lock pieces  26 R extending up substantially at a right angle from rear end parts of the left and right side edges of the lower wall  25 . Left and right positioning protrusions  27  are disposed between the front and rear resilient lock pieces  26 F,  26 R on the left and right side edges of the lower wall  25 . 
     The lid  24  is assembled with the holding member  12  to close the lower surface (surface in which the groove portions  16  are open over the entire length areas from the front ends to the rear ends) of the holding member  12 . In an assembled state, the lower wall  25  is in contact with the lower end surfaces of the left and right side walls  14  and the lower end surface of the separation wall  15  to position the holding member  12  and the lid  24  vertically. Further, the front lock projections  21 F and the front resilient lock pieces  26 F are locked and the rear lock projections  21 R and the rear resilient lock pieces  26 R are locked to restrict vertical separation and lateral relative displacements of the holding member  12  and the lid  24 . Further, the positioning recesses  22  and the positioning protrusions  27  are fit to restrict relative displacements of the holding member  12  and the lid  24  in the front-rear direction. 
     In the above way, the holding member  12  and the lid  24  are held in a state vertically united and mounted. By uniting the holding member  12  and the lid  24 , the conductor accommodation chambers  17  are formed inside the body  11  by the grooves  16  and the lower wall  25 . In other words, each conductor accommodation chamber  17  is a space enclosed by the upper wall  13 , one side wall  14 , the separation wall  15  and the lower wall  25 . Further, the conductor accommodation chambers  17  are partitioned in an insulated state by the separation wall  15 . The front end of the conductor accommodation chamber  17  is open in the front surface of the body  11  and the rear end thereof is open in the rear surface of the body  11 . 
     The front wall  28  is a single component including a wall body  29  and left and right positioning portions  30  projecting rearward from the rear surface of the wall body  29 . Upper and lower fitting projections  31  are cantilevered rearward from left and right end parts of the rear surface of the wall body  29 . A diameter enlarged portion  32  is formed on a projecting end (rear end part) of each fitting projection  31 . 
     Left and right tab insertion openings  33  having square cross-sections penetrate through the wall body  29  in the front-rear direction (wall thickness direction of the wall body  29 ). Elongated tabs  47  on tips of mating inner conductors  46  are inserted into the tab insertion openings  33 . Left and right guiding surfaces  34  are formed in the front surface of the wall body  29 . Each guiding surface  34  is formed by tapering a square frame-like area along a hole edge of each tab insertion opening  33  in the front surface of the wall body  29 . If the tab  47  comes into contact with the guiding surface  34 , the tab  47  is guided into the tab insertion opening  33  by the inclination of the guiding surface  34 . 
     Each positioning portion  30  is in the form of a rectangular tube cantilevered rearward from the rear surface of the wall body  29 . A back view shape of the positioning portion  30  is rectangular, as shown in  FIG. 9 , and an erroneous fitting restricting recess  35  recessed upward is formed in a right side part of an upper end part. The tab insertion opening  33  is open in a front of each positioning portion  30 . The inside of the positioning portion  30  is open rearward. 
     The front wall  28  is mounted on the front surface of the body member  11 . The dielectric is configured by assembling the front wall  28  with the body  11 . The front wall  28  and the body  11  are locked in an assembled state by press-fitting the fitting projections  31  into the fitting holes  20  and locking the diameter enlarged portions  32  on the tips of the fitting projections  31  to hole edge parts of the fitting holes  20  on the rear surface. 
     The inner conductor  36  is formed by applying bending and the like to a metal plate material, and is elongated in the front-rear direction as a whole. A rectangular tubular conductor body  37  is formed in a front end area of the inner conductor  36 , and a crimping portion  38  in the form of an open barrel is formed in a rear end area of the inner conductor  36 . A front part of the conductor body portion  37  is formed with a stabilizer  39  (see  FIG. 2 ) projecting up from the upper surface thereof. A rear end part of the conductor body  37  is formed with a retaining projection  40  projecting up from the upper surface thereof. 
     Front end parts of two wires  42  are connected individually and conductively to the two inner conductors  36 . In particular, the front part of the wire  42  is crimped conductively and substantially coaxially to each crimping portion  38 . The two wires  42  constitute a twisted pair cable  41  by being spirally twisted each other. The twisted pair cable  41  is integrated while being collectively enclosed by a tubular insulating member  43  and constitutes a signal circuit. 
     The front end part of the inner conductor  36  is fit into each positioning portion  30  from behind the front wall  28 . The inner conductor  36  fit in the positioning portion  30  is positioned with relative displacements in the vertical and lateral directions restricted with respect to the front wall  28 . Further, the stabilizer  39  is accommodated into the erroneous fitting restricting recess  35 . 
     Accordingly, if it is attempted to fit the inner conductor  36  in a vertical inverted orientation into the positioning portion  30 , the stabilizer  39  interferes with the rear end edge of a lower end part of the positioning portion  30  so that the inner conductor  36  is prevented from being fit in a wrong vertically inverted orientation into the positioning portion  30  (front wall  28 ). 
     Each inner conductor  36  is accommodated into the conductor accommodation chamber  17 . The inner conductor  36  accommodated in the conductor accommodation chamber  17  is in contact with the upper wall  13 , the lower wall  25 , the side wall  14  and the separation wall  15 , thereby being held with relative displacements in the vertical and lateral directions restricted with respect to the conductor accommodation chamber  17  (dielectric  10 ). Further, by fitting the retaining projection  40  and the retaining recess  18 , the inner conductor  36  is held with relative displacements in the front-rear direction restricted with respect to the conductor accommodation chamber  17  (dielectric  10 ). 
     The dielectric  10  is configured by assembling three components, i.e. the holding member  12 , the lid  24  and the front wall  28 . Polypropylene (PP) is used as a material of the holding member  12 . A material of the lid  24  is also polypropylene. That is, the holding member  12  and the lid  24  constituting the body member  11  are made of the same material. On the other hand, polybutylene terephthalate (PBT), which is synthetic resin having a relatively high mechanical strength, is used as a material of the front wall  28  constituting a front surface part of the dielectric  10 . 
     Polybutylene as the material of the body  11  has a lower mechanical strength and a lower dielectric constant (relative dielectric constant) than polypropylene terephthalate. In selecting the material of the body  11 , it is considered that the inner conductors  36  constitute the signal circuit and the holding member  12  is formed integrally with the separation wall portion  15  partitioning between the two inner conductors  36 . Thus, polypropylene, which is synthetic resin less affecting signal transmission, i.e. having a relatively low dielectric constant (relative dielectric constant), is selected as the material of the body  11 . 
     On the other hand, in selecting the material of the front wall  28 , a possibility that the tabs  47  are pierced into the guiding surfaces  34  in the front surface of the front wall  28  due to tolerances and the like is considered since the elongated tabs  47  of the mating inner conductors  46  are inserted into the tab insertion openings  33  from the front of the dielectric  10 . Thus, polybutylene having such a mechanical strength as not to be pierced by the tabs  47  is selected as the material of the front wall  28 . 
     Next, an assembling procedure of the connector  1  of the first embodiment is described. The front part of the wire  42  is crimped to the rear part of each inner conductor  36 . The two inner conductors  36  having the wires  42  crimped thereto are fit individually into the left and right positioning portions  30  of the front wall  28 , thereby being positioned in the vertical and lateral directions with respect to the front wall  28 . Thereafter, the front wall  28  and the two inner conductors  36  are set in the vertically inverted holding member  12 . 
     At this time, each inner conductor  36  is accommodated into the respective groove  16  with the front wall  28  located slightly before a proper mounting position. Since a mounting direction of the inner conductor  36  into the groove  16  at this time is substantially at a right angle to axial directions of the inner conductor  36  and the wire  42  (front-rear direction), a length of an area of the front end part of each of the two wires  42  exposed from the front end of the insulating member  43  and untwisted can be shorter as compared to the case where the inner conductors  36  are inserted into the grooves  16  (conductor accommodation chambers  17 ) from behind. Thus, an electromagnetic shielding function as the twisted pair cable  41  is excellent. 
     The wall body  29  is separated forward of the holding member  12  with the front wall  28  and the inner conductors  36  integrally set in the holding member  12 . Thus, the positions of the inner conductors  36  also are displaced forward from proper mounting positions. To correct these displacements, the inner conductors  36  are moved rearward together with the front wall  28  and the rear surface of the wall body  29  is brought into contact with the front surface of the holding member  12 . At this time, the fitting projections  31  of the front wall  28  are press-fit into the fitting holes  20  of the holding member  12  and the diameter enlarged portions  32  of the fitting projections  31  are locked to the holding member  12 . In the above way, the front wall  28  is assembled properly with the holding member  12  and the inner conductors  36  are accommodated at proper positions in the grooves  16 . 
     With the inner conductors  36  properly accommodated in the grooves  16 , the retaining projections  40  are locked into the retaining recesses  18  so that the inner conductors  36  are held so that displacements in the front-rear direction are restricted with respect to the holding member  12  (grooves  16 ). Further, the positioning portions  30  are fit into the escaping recesses  19  of the holding member  12 . In the above way, the front wall  28  and the two inner conductors  36  are integrated with the holding member  12 . 
     Thereafter, the lid  24  is brought vertically closer to the holding member  12  and united. With the holding member  12  and the lid  24  united, the front resilient lock pieces  16 F and the front lock projections  21 F are locked, the rear resilient lock pieces  26 R and the rear lock projections  21 R are locked and the positioning recesses  22  and the positioning protrusions  27  are locked to unite the holding member  12  and the lid. In the above way, the two inner conductors  36  are accommodated in the dielectric  10  at the same time as the assembling of the dielectric  10  is completed. The dielectric  10  having the inner conductors  36  mounted therein is inserted into the housing  44  and locked in a retained state by the locking of locking lances  45  and the locking projection  23 . 
     The connector  1  of the first embodiment is designed for combining an improvement of communication performance and a reliability improvement of a connecting operation, and includes the dielectric  10  and the inner conductors  36 . The dielectric  10  includes two conductor accommodation chambers  17  laterally partitioned by the separation wall  15 , and the two inner conductors  36  are accommodated individually into the two conductor accommodation chambers  17 . 
     The dielectric  10  includes the body  11  made of synthetic resin and formed with the separation wall  15  and the two conductor accommodation chambers  17 , and the front wall  28  made of synthetic resin and mounted on the front part of the body  11  to close front end openings of the conductor accommodation chambers  17 . The front wall  28  is formed with the tab insertion openings  33  allowing the tabs  47  of the mating inner conductors  46  to be inserted into the conductor accommodation chambers  17  from the front of the dielectric  10 . 
     The separation wall  15  is made of the synthetic resin material (polypropylene) having a lower dielectric constant than the front wall  28 . The front wall  28  is made of the material (polybutylene terephthalate) having a higher mechanical strength than the separation wall  15 . In the connector of the first embodiment, the separation wall  15  is interposed between the two inner conductors  36  and is made of the material having a relatively low dielectric constant. Thus, the communication performance of electrical signals passing through the inner conductors  36  is guaranteed. Further, the front wall  28  is made of the material having a higher mechanical strength than the separation wall  15 . Thus, even if the tabs  47  of the mating inner conductors  46  interfere with the front wall  28 , there is no possibility that the tabs  47  are pierced into the front wall  28 . 
     Further, the two wires  42  connected to the rear end parts of the inner conductors  36  constitute the twisted pair cable  41 . Thus, in the case of inserting the inner conductors  36  connected to the respective wires  42  into the conductor accommodation chambers  17  from behind the body  11 , untwisted lengths of the wires  42  need to be increased. However, in the first embodiment, the dielectric  10  is divided into the holding member  12  and the lid  24 , and the holding member  12  is formed with the separation wall  15  and the two grooves  16  constituting the two conductor accommodation chambers  17 . The lid  24  is mounted on the holding member  12  to close openings of the two groove portions  16 . A mounting direction of the lid  24  and the holding member  12  is the vertical direction intersecting length directions of the inner conductors  36  and the wires  42 . According to this configuration, it is not necessary to insert the two inner conductors  36  into the conductor accommodation chambers  17  from behind the dielectric  10 . Consequently, the untwisted lengths of the wires  42  can be shortened, and reduction of the shielding function of the twisted pair cable  41  can be avoided. 
     Further, the front wall  28  is formed with the positioning portions  30  capable of positioning the front end parts of the two inner conductors  36 . According to this configuration, the two inner conductors  36  can be accommodated into the two grooves  16  in one action by integrating the two inner conductors  36  with the front wall  28  with the two inner conductors  36  positioned by the positioning portions  30 . 
     Second Embodiment 
     A second embodiment of the present invention is described with reference to  FIGS. 11 to 21 . Note that, in the following description, a left side in  FIGS. 12 to 17  is defined as a front side concerning a front-rear direction. Upper and lower sides shown in  FIGS. 11, 12, 14, 16 and 18 to 20  are defined as upper and lower sides concerning a vertical direction.] 
     A connector  2  of the second embodiment includes a dielectric  50  made of synthetic resin, inner conductors  76  and a housing  85  made of synthetic resin. The dielectric  50  includes a body  51  internally formed with left and right conductor accommodation chambers  57  and a front wall  69  to be assembled with a front end part of the body  51 . The body  51  is configured by assembling a holding member  52  and a lid  64 . 
     As shown in  FIGS. 14 and 15 , the holding member  52  is long and narrow in the front-rear direction. The holding member  52  includes an upper wall  53  long in the front-rear direction, two side walls  54  extending down substantially at a right angle from both left and right side edges of the upper wall  53  over the entire lengths thereof, and a separation wall  55  extending down from a center of the upper wall  53  in a lateral direction (width direction) substantially at a right angle over the entire length thereof. 
     Spaces enclosed by the upper wall  53  and the side walls  54  of the holding member  52  serve as grooves  56  laterally partitioned by the separation wall  55 . Each groove  56  constitutes the conductor accommodation chamber  57 . Each groove  56  is elongated in the front-rear direction and is open in the lower surface of the holding member  52  over the entire length thereof. A retaining recess  58  is formed in the inner upper surface of each groove  56 . The front end of the groove  56  is open in the front surface of the holding member  52 , and the rear end of the groove portion  56  is open in the rear surface of the holding member  52 . 
     Two vertically spaced fitting holes  60  (fitting portions as claimed) are formed on the front end surface of each of the left and right side walls  54 . Two front lock projections  61 F are formed on front end parts of outer side surfaces of the left and right side walls  54 , and two rear lock projections  61 R are formed on rear end parts of the outer side surfaces of the left and right side walls  54 . Further, positioning recesses  62  are formed in the outer surfaces of the left and right side walls  54  at positions between the front and rear lock projections  61 F and  61 R. A locking projection  63  is formed on an outer surface (upper surface) of the upper wall  53 . 
     As shown in  FIGS. 16 and 17 , the lid  64  is long and narrow in the front-rear direction. The lid  64  is a single component including a lower wall  65  long in the front-rear direction, two front resilient lock pieces  66 F extending up substantially at a right angle from front end parts of both left and right side edges of the lower wall  65  and two rear resilient lock pieces  66 R extending up substantially at a right angle from rear end parts of the left and right side edges of the lower wall  65 . Left and right positioning protrusions  67  are formed on the both left and right side edges of the lower wall  65  at positions between the front and rear resilient lock pieces  66 F,  66 R. A pressure receiving portion  68  is formed by shallowly recessing a laterally central part of an outer surface (lower surface) of a front end part of the lower wall  65 . 
     The lid  64  is assembled with the holding member  52  in such a state as to close the lower surface (surface in which the grooves  56  are open over the entire length areas from the front ends to the rear ends) of the holding member  52 . In an assembled state, the lower wall  65  is in contact with the lower end surfaces of the left and right side walls  54  and the lower end surface of the separation wall  55  to position the holding member  52  and the lid  64  vertically. Further, the front lock projections  61 F and the front resilient lock pieces  66 F are locked and the rear lock projections  61 R and the rear resilient lock pieces  66 R are locked to restrict vertical separation and lateral relative displacements of the holding member  52  and the lid  64 . Further, the positioning recesses  62  and the positioning protrusions  67  are fit to restrict relative displacements of the holding member  52  and the lid  64  in the front-rear direction. 
     In the above way, the holding member  52  and the lid  64  are held in a state vertically united and mounted. By uniting the holding member  52  and the lid  64 , the conductor accommodation chambers  57  are formed by the grooves  56  and the lower wall  65  inside the body member  51 . In other words, each conductor accommodation chamber  57  is a space enclosed by the upper wall  53 , one side wall  54 , the separation wall  55  and the lower wall  65 . Further, the two conductor accommodation chambers  57  are partitioned in an insulated state by the separation wall  55 . The front end of the conductor accommodation chamber  57  is open in the front surface of the body  51  and the rear end thereof is open in the rear surface of the body  51 . 
     The front wall  69  is a single component including a wall body  70  and a pressing portion  71 . The pressing portion  71  is in the form of a plate cantilevered rearward substantially at a right angle from a laterally central part of a lower end edge of the wall body  70 . A pair of upper and lower fitting projections  72  (fitting portions as claimed) cantilevered rearward are formed on each of both left and right end parts of the rear surface of the wall body portion  70 . A diameter enlarged portion  73  is formed on a projecting end part (rear end part) of each fitting projection  72 . 
     Left and right tab insertion openings  74  penetrate through the wall body  70  in the front-rear direction (wall thickness direction of the wall body  70 ) and have square cross-sections. Elongated tabs  84  on tips of mating inner conductors  83  are inserted into the tab insertion openings  74 . Left and right guiding surfaces  75  are formed in the front surface of the wall body  70 . Each guiding surface  75  is formed by tapering a square frame-like area along an edge part of each tab insertion opening  74  in the front surface of the wall body  70 . A tab  84  that contacts the guiding surface  75  is guided into the tab insertion opening  74  by the inclination of the guiding surface  75 . 
     The front wall  69  is mounted on the front surface of the body  51 . By assembling the front wall  69  with the body  51 , the dielectric  50  is configured. The front wall  69  and the body  51  are locked in an assembled state by press-fitting the fitting projections  72  into the fitting holes  60  and locking the diameter enlarged portions  73  on the tips of the fitting projections  72  to rear edges of the fitting holes  60 . 
     The inner conductor  76  is formed by applying bending and the like to a metal plate material, and is elongated in the front-rear direction. A rectangular tubular conductor body  77  is formed in a front end area of the inner conductor  76 , and a crimping portion  78  forms an open barrel in a rear end area of the inner conductor  76 . A rear end part of the conductor body  77  is formed with a retaining projection  79  projecting up from the upper surface thereof. 
     Front end parts of two wires  81  are connected individually and conductively to the two inner conductors  76 . In particular, the front part of the wire  81  is crimped conductively and substantially coaxially to each crimping portion  78 . The two wires  81  constitute a twisted pair cable  80  by being spirally twisted each other. The twisted pair cable  80  is integrated while being collectively enclosed by a tubular insulating member  82  and constitutes a signal circuit. 
     Each inner conductor  76  is accommodated into the conductor accommodation chamber  57 . The inner conductor  76  accommodated in the conductor accommodation chamber  57  is in contact with the upper wall  53 , the lower wall  65 , the side wall  54  and the separation wall  55 , thereby being held with relative displacements in the vertical and lateral directions restricted with respect to the conductor accommodation chamber  57  (dielectric  50 ). Further, the fitting of the retaining projection  79  and the retaining recess  58  holds the inner conductor  76  with relative displacements in the front-rear direction restricted with respect to the conductor accommodation chamber  57  (dielectric  50 ). 
     The dielectric  50  is configured by assembling three components, i.e. the holding member  52 , the lid  64  and the front wall  69 . Polypropylene (PP) is used as a material of the holding member  52 . A material of the lid  64  is also polypropylene. That is, the holding member  52  and the lid  64  constituting the body member  51  are made of the same material. On the other hand, polybutylene terephthalate (PBT), which is synthetic resin having a relatively high mechanical strength, is used as a material of the front wall  69  constituting a front surface part of the dielectric  50 . 
     Polybutylene as the material of the body member  51  has a lower mechanical strength and a lower dielectric constant (relative dielectric constant) than polypropylene terephthalate. In selecting the material of the body  51 , it is considered that the inner conductors  76  constitute the signal circuit and the holding member  52  is formed integrally with the separation wall  55  partitioning between the two inner conductors  76 . Thus, polypropylene, which is synthetic resin less affecting signal transmission, i.e. having a relatively low dielectric constant (relative dielectric constant), is selected as the material of the body  51 . 
     On the other hand, in selecting the material of the front wall  69 , a possibility that the tabs  84  are pierced into the guiding surfaces  75  in the front surface of the front wall  69  due to tolerances and the like is considered since the elongated tabs  84  of the mating inner conductors  83  are inserted into the tab insertion openings  74  from the front of the dielectric  50 . Thus, polybutylene having such a mechanical strength as not to be pierced by the tabs  84  is selected as the material of the front wall  69 . 
     Next, an assembling procedure of the connector  2  of the second embodiment is described. The front end part of the wire  81  is crimped to the rear end part of each inner conductor  76 . The two inner conductors  76  having the wires  81  crimped thereto are set in the vertically inverted holding member  52  and individually accommodated into the grooves  56 . With the inner conductors  76  properly accommodated in the grooves  56 , the retaining projections  79  are locked to the retaining recesses  58 . Thus, the inner conductors  76  are held with displacements in the front-rear direction restricted with respect to the holding member  52  (groove portions  56 ). 
     A mounting direction of each inner conductor  76  into the groove  56  is substantially at a right angle to axial directions of the inner conductor  76  and the wire  81  (front-rear direction). Thus, a length of an area of the front end part of each of the two wires  81  exposed from the front end of the insulating member  82  and untwisted part can be shorter as compared to the case where the inner conductors  76  are inserted into the grooves  56  (conductor accommodation chambers  57 ) from behind. Thus, an electromagnetic shielding function as the twisted pair cable  80  is excellent. 
     Thereafter, the lid  64  is brought vertically closer to the holding member  52  and united. With the holding member  52  and the lid  64  united, the front resilient lock pieces  66 F and the front lock projections  61 F are locked, the rear resilient lock pieces  66 R and the rear lock projections  61 R are locked and the positioning recesses  62  and the positioning protrusions  67  are locked to hold the holding member  52  and the lid  64  in a united state. In the united state, the two inner conductors  76  are held accommodated in the conductor accommodation chambers  57 . 
     After the holding member  52  and the lid  64  are united, the front wall  69  is mounted on the body  51  by bringing the front wall  69  brought closer to the body  51  from the front and the rear surface of the wall body  70  is brought into contact with the front surface of the body  51 . At this time, the fitting projections  72  of the front wall  69  are fit into the fitting holes  60  of the body  51  and the diameter enlarged portions  73  of the fitting projections  72  are locked to the body  51 . In the above way, the front wall  69  is assembled properly assembled with the body  51 . 
     Further, with the lid  64  mounted on the body  51 , the wall body  70  of the lid  64  is held mounted by being press-fit to the holding member  52 , and the pressing portion  71  is in surface contact with the pressure receiving portion  68  of the lid  64  from below. By this contact of the pressing portion  71 , a downward displacement of the front part of the lid  64  in a direction to be separated from the holding member  52  is restricted. In the above way, the two inner conductors  76  are accommodated in the dielectric  50  at the same time as the assembling of the dielectric  50  is completed. The dielectric  50  having the inner conductors  76  mounted therein is inserted into the housing  85  and locked in a retained state by locking the locking projection  63  to locking lances  86 . 
     The connector  2  of the second embodiment is designed for the purpose of combining an improvement of communication performance and a reliability improvement of a connecting operation, and includes the dielectric  50  and the inner conductors  76 . The dielectric  50  includes two conductor accommodation chambers  57  laterally partitioned by the separation wall  55 , and the two inner conductors  76  are individually accommodated into the two conductor accommodation chambers  57 . 
     The dielectric  50  includes the body  51  made of synthetic resin. The body  51  is formed with the separation wall  55  and the two conductor accommodation chambers  57 . The front wall  69  is made of synthetic resin and is mounted on the front of the body  51  to close front openings of the conductor accommodation chambers  57 . The front wall  69  is formed with the tab insertion openings  74  allowing the tabs  84  of the mating inner conductors  83  to be inserted into the conductor accommodation chambers  57  from the front of the dielectric  50 . 
     The separation wall  55  is made of the synthetic resin material (polypropylene) having a lower dielectric constant than the front wall  69 . The front wall  69  is made of the material (polybutylene terephthalate) having a higher mechanical strength than the separation wall  55 . In the connector  2  of the second embodiment, the separation wall  55  interposed between the two inner conductors  76  is made of the material having a relatively low dielectric constant. Thus, the communication performance of electrical signals passing through the inner conductors  76  is guaranteed. Further, since the front wall  69  is made of the material having a higher mechanical strength than the separation wall  55 , even if the tabs  84  of the mating inner conductors  83  interfere with the front wall  69 , there is no possibility that the tabs  84  are pierced into the front wall member  69 . 
     Further, the two wires  81  connected to the rear end parts of the inner conductors  76  constitute the twisted pair cable  80 . If the inner conductors  76  connected to the respective wires  81  were inserted into the conductor accommodation chambers  57  from behind, the body member  51 , untwisted lengths of the wires  81  need to be increased. However, in the second embodiment, the dielectric  50  is divided into the holding member  52  and the lid  64 , and the holding member  52  is formed with the separation wall  55  and the two grooves  56  constituting the two conductor accommodation chambers  57 . 
     The lid  64  is mounted on the holding member  52  to close openings of the two grooves  56 . According to this configuration, it is not necessary to insert the two inner conductors  76  into the conductor accommodation chambers  57  from behind the dielectric  50 . Thus, the untwisted lengths of the wires  81  can be shortened and, consequently, a reliability reduction of the shielding function of the twisted pair cable  80  can be avoided. 
     Further, the front wall  69  and the holding member  52  are formed with the fitting portions (fitting projections  72  and fitting holes  60 ) for holding the front wall  69  and the holding member  52  in the assembled state by being fit to each other. The front wall  69  has the pressing portion  71  for holding the lid  64  assembled with the holding member  52  by being held in contact with the outer surface of the lid  64  when the lid  60  is assembled with the holding member  52 . Accordingly, the lid  64  and the holding member  52  are held reliably in the assembled state. 
     The invention is not limited to the above described and illustrated embodiments. For example, the following embodiments also are included in the scope of the invention. 
     Although the holding member is a component made of the single material in the above first and second embodiments, the holding member may be a single component formed by making the separation wall and parts other than the separation wall of different materials and integrating the separation wall and the other parts by two-color molding. 
     Although the separation wall is formed integrally to the holding member in the first and second embodiments, the separation wall may be a component separate from the holding member. 
     Although two inner conductors are accommodated into one dielectric in the first and second embodiments, one, three or more inner conductors may be accommodated into one dielectric. 
     Although the body is composed of two components, i.e. the holding member and the lid, in the first and second embodiments, the body may be a single component. 
     Although the wires connected to the inner conductors constitute the twisted pair cable in the above first and second embodiments, the invention can also be applied to a case where the wires connected to the inner conductors do not constitute the twisted pair cable. 
     Although the separation wall(holding member) is made of polypropylene (PP) in the first and second embodiments, the separation wall (holding member) may be made of polyethylene (PE), polystyrene (PS), foamed polybutylene terephthalate or the like. 
     Although the front wall is made of polybutylene terephthalate (PBT) in the first and second embodiments, the front wall may be made of a material other than polybutylene terephthalate. 
     Although a combination of the materials of the front wall and the separation wall is a combination of polybutylene terephthalate and polypropylene in the first and second embodiments, this combination may be a combination of polybutylene terephthalate and polyethylene (PE) or a combination of polybutylene terephthalate and foamed polybutylene terephthalate. 
     LIST OF REFERENCE SIGNS 
       1 ,  2  . . . connector 
       10 ,  50  . . . dielectric 
       11 ,  51  . . . body 
       12 ,  52  . . . holding member 
       15 ,  55  . . . separation wall 
       16 ,  56  . . . groove 
       17 ,  57  . . . conductor accommodation chamber 
       20 ,  60  . . . fitting hole (fitting portion) 
       24 ,  64  . . . lid 
       28 ,  69  . . . front wall 
       30  . . . positioning portion 
       31 ,  72  . . . fitting projection (fitting portion) 
       33  . . . tab insertion opening 
       36  . . . inner conductor 
       46  . . . mating inner conductor 
       47  . . . tab 
       71  . . . pressing portion