Patent Publication Number: US-7223135-B2

Title: Terminal fitting and a connector provided therewith

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a terminal fitting and to a connector provided therewith. 
   2. Description of the Related Art 
   U.S. Pat. No. 5,235,743 and Japanese Unexamined Patent Publication No. 05-190227 disclose a terminal fitting with a rectangular tube that has a front end for receiving a tab. A resilient contact extends in forward and backward directions in the rectangular tube and contacts the tab inserted into the rectangular tube. A locking hole is formed in a plate of the rectangular tube at a side of the resilient contact opposite the tab. The terminal fitting is inserted into a cavity of a connector housing and is retained therein by the engagement of the locking hole with a resiliently deformable lock provided at an inner wall of the cavity. 
   The resilient contact is accessible through the locking hole from the outside of the rectangular tube. Thus, there is a possibility that external matter may intrude into the rectangular tube through the locking hole and may displace the resilient contact sufficiently to plastically deform a support of resilient deformation of the resilient contact while narrowing the tab entrance space. As a result, frictional resistance between the resilient contact and the tab may be increased. 
   Consideration may be given to forming the resilient contact with projections that project out along the width direction from the opposite left and right edges of the resilient contact. The projections could engage edges of locking holes formed in side plates of the rectangular tube. The engagement of the projections with the locking holes limits the amount of displacement of the resilient contact that can be caused by the intrusion of external matter through the locking hole. 
   However, the locking holes can reduce the strength of the side plates and hence can reduce the strength of the entire rectangular tube. 
   The invention was developed in view of the above problem, and an object thereof is to improve a terminal fitting and a connector provided therewith, and particularly to prevent plastic deformation of a resilient contact piece caused by external matter that enters through a locking hole and/or to avoid a reduction in the strength of a rectangular tube portion. 
   SUMMARY OF THE INVENTION 
   The invention relates to a terminal fitting with a tube for receiving a tab insertable from the front. A resilient contact is provided in the tube and extends substantially in forward and backward directions. The resilient contact is configured to contact the tab while being resiliently deformed. Displacement restricting portions are provided at longitudinal positions for restricting displacement of the resilient contact towards the tab entrance space by contacting a lateral edge of the resilient contact. 
   A locking hole preferably is formed in a plate of the tube at a side of the resilient contact substantially opposite to a tab entrance space. The terminal fitting can be inserted in a cavity of a connector housing and is retained by the engagement of the locking hole with a lock provided at an inner wall of the cavity. 
   Two displacement restricting portions preferably are provided at two positions before and behind the locking hole in the tube. 
   External matter could intrude through the locking hole and could push the resilient contact. However, the displacement of the resilient contact towards the tab entrance space is restricted by the displacement restricting portions at the two positions before and behind the locking hole. Thus, there is no likelihood that the resilient contact piece will incline forward or backward in response to a pushing force from the external matter. Therefore, the plastic deformation of a supporting point of resilient deformation of the resilient contact piece cannot be deformed plastically. 
   At least one of the displacement restricting portions is near a contact point of the resilient contact with the tab. Thus, the position of the contact point will not change significantly even if the resilient contact is deformed. Accordingly, the resilient contact can be held in contact with the tab with a proper contact pressure. 
   The resilient contact cantilevers from a plate of the tube, and one of the displacement restricting portions preferably is near a free end of the resilient contact. Thus, a distance between the front and rear displacement restricting portions is long. Accordingly, the amount of deformation is small when external matter pushes the resilient contact between the front and rear displacement restricting portions. As a result, plastic deformation is unlikely to occur between the front and rear displacement restricting portions of the resilient contact. 
   The terminal fitting preferably is formed by bending a conductive plate to define a rectangular tube that is hollow in forward and backward directions. The tube preferably has a base plate and first and second side plates that extend from opposite sides of the base plate. A ceiling plate extends from the first side plate. At least one locking plate projects substantially perpendicularly from an edge of the ceiling plate and extends along the inner surface of the second side plate. 
   At least one lateral edge of the resilient contact preferably can contact an extending edge of the locking plate to restrict displacement of the resilient contact piece towards the tab entrance space. Thus, it is not necessary to form a locking hole in the side plate. Accordingly, the side plate and the entire tube are strong. 
   At least one projection preferably projects out in the width direction from a lateral edge of the resilient contact. The projection preferably can contact a portion of the locking plate. 
   The widthwise center of the inner space of the tube is deviated from the widthwise center of the outer surfaces of the tube due to the presence of the locking plate. The resilient contact would have to be narrowed by as much as this deviation if an attempt was made to arrange the resilient contact and the tube portion so that their widthwise centers coincide. As a result, a dead space is defined at a side opposite to the locking plate in the inner space of the tube. Moreover, the widthwise center of the resilient contact is deviated from that of the tube towards the side opposite to the locking plate. Therefore, a wide resilient contact is achieved and the dead space in the tube is small. 
   At least one pressing portion preferably extends from one side plate of the tube and contacts an upper edge of the locking plate from above. The pressing portion prevents an upward displacement of the locking plate, and hence displacement of the resilient contact towards the tab entrance space is prevented more securely. 
   The upper edge of the locking plate preferably forms a recess, and at least part of the pressing portion is accommodated in the recess. Thus, there is little or no step between the upper surface of the ceiling plate and the upper surface of the pressing portion. 
   The invention also relates to a connector with a housing having at least one cavity and at least one of the above described terminal fittings is inserted into the cavity. 
   These and other features of the invention will become more apparent upon reading the following detailed description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a right side view of a terminal fitting according to one embodiment of the invention. 
       FIG. 2  is a plan view of the terminal fitting. 
       FIG. 3  is a left side view of the terminal fitting. 
       FIG. 4  is a bottom view of the terminal fitting. 
       FIG. 5  is a section along  5 — 5  of  FIG. 2 . 
       FIG. 6  is a section along  6 — 6  of  FIG. 5 . 
       FIG. 7  is a section along  7 — 7  of  FIG. 5 . 
       FIG. 8  is a section along  8 — 8  of  FIG. 5 . 
       FIG. 9  is a section along  9 — 9  of  FIG. 5 . 
       FIG. 10  is a development of the terminal fitting. 
       FIG. 11  is a front view of the terminal fitting. 
       FIG. 12  is a section showing a state where a front plate is at a full locking position and a tab is connected with the terminal fitting. 
       FIG. 13  is a front view of a connector housing showing a state where the front plate is at the full locking position. 
       FIG. 14  is an enlarged partial view of  FIG. 13 . 
       FIG. 15  is a section showing a state where the front plate is at a partial locking position. 
       FIG. 16  is a front view of the connector housing showing the state where the front plate is at the partial locking position. 
       FIG. 17  is an enlarged partial view of  FIG. 16 . 
       FIG. 18  is a section showing a state where an electrical connection test is conducted using probes. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A terminal fitting according to the invention is identified by the letter T in  FIGS. 1 to 12 . The terminal T can be used with a connector housing identified by the numeral  50  in  FIGS. 13 to 18 . The housing  50  is made e.g. of a synthetic resin and cavities  51  penetrate the housing  50  in forward and backward directions. A lock  52  is cantilevered forward along the bottom wall of each cavity  51  and a retaining projection  52   a  is formed on the surface of each lock  52  facing the cavity  51 . 
   A front plate  53  is movable vertically along the front of the housing  50  and substantially normal to the forward and backward directions between a partial locking position  1 P and a full locking position  2 P. Tab insertion openings  55  and work openings  56  extend through the front plate  53 . The work openings  56  substantially align with the cavities  51  when the front plate  53  is at the partial locking position  1 P shown in  FIGS. 15 to 17 . The tab insertion openings  55  are slightly above the centers of the cavities  51  and the work openings  56  are at positions substantially corresponding to the locks  52  when the front plate  53  is at the full locking position  2 P shown in  FIGS. 12 to 14 . 
   Each terminal fitting T is formed from a conductive metallic plate material Ta stamped or cut out into a specified shape as shown in  FIG. 10  by applying bending, folding, pressing, embossing, etc. and is substantially narrow and long in forward and backward directions. A front portion of the plate Ta is configured to form a substantially rectangular tube  10  and a rear portion is configured to form a wire connecting portion  11  with open barrels that can be crimped, bent or folded into electrical connection with an end of a wire W. 
   The rectangular tube  10  of the terminal T is substantially hollow in forward and backward directions and has a bottom plate  12  that is long and narrow in forward and backward directions. Left and right side plates  13 L,  13 R project up from the opposite left and right sides of the bottom plate  12 . A ceiling plate  14  extends from the top of the left side plate  13 L towards the right side plate  13 R and is substantially parallel with the bottom plate  12 . Front, rear and intermediate parts of the extending right edge of the ceiling plate  14  contact the upper edge of the right side plate  13 R from above, and front and rear locking plates  15 F,  15 R are formed in front and rear areas of the extending end of the ceiling plate  14  that do not contact the upper edge of the right side plate  13 R. The locking plates  15 F,  15 R extend down substantially along the inner surface of the right side plate  13 R. The front locking plate  15 F is substantially rectangular and the bottom edge thereof is in an intermediate position of the rectangular tube  10  with respect to the height direction. A rear notch  16  is formed at the rear end of the bottom edge of the front locking plate  15 F. The rear locking plate  15 R also is substantially rectangular, and the bottom edge thereof is at a low position near the bottom plate  12  in the rectangular tube  10 . A bottom notch  17  is formed in an intermediate position of the bottom edge of the rear locking plate with respect to forward and backward directions. Substantially rectangular front and rear locking holes  18 F,  18 R penetrate the left side plate at positions corresponding respectively to the bottom edge of the front locking plate  15 F and the bottom notch  17  of the rear locking plate  15 R. 
   A substantially rectangular locking hole  19  is formed in the bottom plate  12 . Additionally, the bottom edges of the left and right side plates  13 L,  13 R are cut to a position slightly higher than the upper surface of the bottom plate  12  in areas corresponding to the locking hole  19  with respect to forward and backward directions to form transversely symmetrical side notches  20 . Thus, the left and right side plates  13 L,  13 R have bottom edges in the opening area of the locking hole  19 . An area of the bottom part of the right side plate  13 R corresponding to the locking hole  19  is embossed to project inward towards the widthwise center, thereby forming an intrusion restricting portion  21 . The intrusion restricting portion  21  is substantially rectangular in side view (see e.g.  FIG. 3 ) and is substantially trapezoidal in bottom view (see e.g.  FIG. 4 ). The rear notch  16  of the front locking plate  15 F is formed to avoid interference with the front end of the upper edge of the intrusion restricting portion  21 . 
   A retaining portion  22  is formed at the front edge of the locking hole  19 . The retaining portion  22  is formed by plastically deforming the opening edge of the locking hole  19  in the bottom plate  12  by stamping or embossing to project up and into the rectangular tube  10 . The retaining portion  22  includes an edge  12 S of the locking hole  19  that will oppose and engage the retaining projection  52   a  of the lock  52  of the housing  50 . The retaining portion  22  is displaced to the left along the width direction relative to the rectangular tube  10 . Further, the upper surface of the retaining portion  22  is a substantially flat surface located substantially at the same height as the bottom edges of the side notches  20  and the intrusion restricting portion  21 . 
   The retaining portion  22  is arranged at a position displaced laterally (e.g. to left) along width direction (transverse direction) relative to the (rectangular) tube portion  10 , wherein the widthwise center of the retaining portion  22  preferably is located at the substantially same position as that of the resilient contact piece  25  to be described later. Further, the upper or inner surface of the retaining portion  22  preferably is a substantially flat surface located substantially at the same height as the bottom edges of the side notches  20  and/or the intrusion restricting portion  21 . 
   A resilient contact  25  is accommodated in the rectangular tube  10 . As shown in  FIG. 5 , the resilient contact  25  is long and narrow in forward and backward directions and is bent to cantilever back from the front end of the bottom plate  12 . The resilient contact  25  has a substantially semicircular bend  26  connected with the front end of the bottom plate  12 , and an extending portion  27  extending back from the bend  26 . The extending portion  27  has a forward inclined portion  28 F extending obliquely up and to the back from the upper end of the bend  26  and a backward inclined portion  28 R extending obliquely down to the back from the rear end of the forward inclined portion  28 F. In a free state where the resilient contact  25  is not resiliently deformed, the resilient contact  25  is supported only at its front end and a free end  25 R of the resilient contact  25  is at a non-contact position spaced up from the bottom plate  12 . The resilient contact  25  is resiliently deformable substantially up and down in a direction intersecting the forward and backward directions with the bend  26  as a supporting point while mainly resiliently deforming the bend  26 . When the resilient contact  25  is deformed down, the free end  25 R of the resilient contact  25  contacts the upper surface of the bottom plate  12  so that the resilient contact  25  is supported at both front and rear ends. 
   The bend  26  and the forward inclined portion  28 F are in an area before the locking hole  19 , and a substantially dome-shaped contact point  29  projects up at the rear end (i.e. highest part) of the front forward portion  28 F. This contact point  29  also is located before the locking hole  19 . The backward inclined portion  28 R extends in an area from the front edge of the locking hole  19  to the bottom notch  17  of the rear locking plate  15 R, and the front end thereof is at a height substantially corresponding to the intrusion restricting portion  21 . Further, the widths of the bend  26  and the forward inclined portion  28 F are substantially equal; the widths of the front and rear ends of the backward inclined portion  28 R are substantially equal to the width of the forward inclined portion  28 F; and an area of the backward inclined portion  28 R except the front and rear ends thereof is narrower than the forward inclined portion  28 F. 
   Front and rear projections  30 F,  30 R are formed at each of the left and right edges of the resilient contact  25 . The front and rear projections  30 F,  30 R are substantially flush with the resilient contact  25  in the thickness direction, but bulge outward transversely. The left and right front projections  30 F are substantially symmetrical to each other and arranged slightly before the contact point  29 . The front projections  30 F substantially correspond to the bottom edge of the front locking plate  15 F and the front locking hole  18 F with respect to forward and backward directions. In the free state, where the resilient contact  25  is not deformed, the upper surface of the right front projection  30 F is slightly below the bottom edge of the front locking plate  15 F and does not contact the bottom edge, and the upper surface of the left front projection  30 F is slightly below the upper edge of the front locking hole  18 F and does not contact this upper edge. On the other hand, the rear projections  30 R are transversely symmetrical and are close to the free rear end  25 R of the resilient contact  25 . The rear projections  30 R are located to correspond to the upper edge of the bottom notch  17  of the rear locking plate  15 R and the rear locking hole  18 R with respect to forward and backward directions. In the free state, where the resilient contact  25  is not resiliently deformed, the upper surface of the right rear projection  30 R is slightly below the upper edge of the bottom notch  17  and not in contact with this upper edge, and the upper surface of the left rear projection  30 R is slightly below the upper edge of the rear locking hole  18 R and not in contact with this upper edge. 
   The resilient contact  25  is substantially transversely symmetrical and displaced to the left along the width direction relative to the rectangular tube  10  and the locking hole  19 . The widthwise center of the resilient contact  25  substantially coincides with that of the retaining portion  22 . When the locking hole  19  is viewed from below, a front-end area of the backward inclined portion  28 R of the resilient contact  25  is exposed over substantially its entire width. The ceiling plate  14  is embossed to project downward, thereby forming a tab receiving portion  31 . The widthwise center of the tab receiving portion  31  also substantially coincides with that of the resilient contact  25 . A space between the upper surface of the resilient contact  25  and the lower surface of the tab receiving portion  31  serves as the tab entrance space  32  for receiving the tab  54  inserted into the rectangular tube  10  from the front. 
   A base portion  33  is formed by cutting or stamping the left and right edges of a front end portion of the bottom plate  12 . Thus, the base portion  33  is narrower than the bottom plate  12  and hence narrower than the substantially rectangular tube  10 . Additionally, the base portion  33  is displaced laterally to the left relative to the rectangular tube  10  or its longitudinal axis. The widthwise center of the base portion  33  substantially coincides with the widthwise center of the resilient contact  25 . Thus, the base portion  33  and the resilient contact  25  are arranged to have their widthwise centers located at the substantially same position. The bottom end of the bend  26  extends unitarily from the front end of the base portion  33 , and the left edge of the base portion  33  and that of the bend  26  are substantially continuous and flush with each other. On the other hand, a bulge  34  bulges out laterally toward the right side plate  13 R from the right edge of the base portion  33  (i.e. at the side edge substantially opposite to the side toward which the base portion  33  is displaced relative to the rectangular tube  10 ). The right edge of the bulge  34  is substantially parallel to the left edge of the base portion  33 , and a front edge  34 F of the bulge  34  is oblique to the side edges of the base portion  33  and the bulge  34 . The widthwise center of a plate portion that comprises the base portion  33  and the bulge  34  substantially coincides with that of the rectangular tube  10 . 
   A substantially flat receiving plate  35  extends from the front edge of the right side plate  13 R substantially at right angle towards the widthwise center and towards the resilient contact  25 . In this regard, the right side plate  13 R is the side plate opposite the side towards which the widthwise center of the resilient contact  25  is deviated. The receiving plate  35  is continuous from a position near the upper end of the right side plate  13 R to a position near the bottom end thereof, and has a vertically long substantially rectangular front view. The receiving plate  35  extends into a space left upon forming the base portion  33  and the bottom edge of the receiving plate  35  is located at least partly within the thickness area of the bottom plate  12  and the upper edge of the receiving plate  35  is substantially at the same height as the lower surface of the tab receiving portion  31 . A front end surface  35 F of the receiving plate  35  is located slightly before the front end of the resilient contact  25 , and hence before the front end of the bend  26 . An extending edge  35 S of the receiving plate  35  is substantially straight and parallel to the right side plate  13 R and is in an area between the inner surface of the right side plate  13 R and the corresponding right surface of the bend  26  and more specifically at a position near the right edge of the bend  26  with respect to the width direction. Thus, the receiving plate  35  is outside the tab entrance space  32  between the tab receiving portion  31  and the resilient contact  25  with respect to the width direction. A slanted guide surface  36 R is formed at the extending edge  35 S of the receiving plate  35 . On the other hand, a similarly slanted guide surface  35 L is formed at the front end of the left side plate  13 L. The widthwise center of a space defined between the extending edge  35 S of the receiving plate  35  and the inner surface of the left side plate  13 L substantially coincides with the widthwise centers of the base portion  33  and the resilient contact  25 . 
   The top part of the front locking plate  15 F and part of the ceiling plate  14  are cut away in an intermediate part with respect to forward and backward directions to form a recess  37 . Therefore, the upper surface of the extending end of the ceiling plate  14  is recessed down (see e.g.  FIG. 7 ) at the recess  37 , and the recess  37  extends down through the lower surface of the ceiling plate  14  in an area of the recess  37  corresponding to the ceiling plate  14 . A pressing portion  38  extends to the left from the top of the right side plate  13 R and is accommodated in the recess  37 . Thus, the upper surface of the pressing portion  38  is substantially flush with the upper surface of the ceiling plate  14 . The pressing portion  38  contacts the upper edge of the front locking plate  15 F from above to prevent an upward or outward displacement of both the front locking plate  15 F and the ceiling plate  14 . 
   The terminal fitting T is inserted into the cavity  51  from behind, with the front plate  43  held at the partial locking position. In the inserting process, the bottom plate  12  of the rectangular tube  10  contacts the retaining projection  52   a  to deform the lock  52  down. The lock  52  resiliently returns up towards the terminal fitting T when the terminal fitting T is inserted to a proper position. As a result, the retaining projection  52   a  enters the locking hole  19  and the front surface of the retaining projection  52   a  engages the retaining portion  22  of the locking hole  19  from behind to retain the terminal fitting T. 
   A long narrow conductive metallic probe P can be inserted through the work opening  56  from the front for checking an electrical connection of the inserted terminal fitting T. The probe P contact the upper end of the receiving plate  35  above the resilient contact  25  and at the height corresponding to the tab entrance space  32  and simultaneously contacts the front edge of the ceiling plate  14 . 
   The front plate  53  is moved to the full locking position after checking the electrical connection. In this state, the tab  54  is inserted into the tab entrance space  32  through the tab insertion opening  55  of the front plate  53  from the front. The inserted tab  54  contacts the resilient contact  25  and is held resiliently between the tab receiving portion  31  and the contact point  29  while resiliently deforming the resilient contact  25 . Thus, the tab  54  and the rectangular tube  10  are connected electrically by a resilient restoring force of the resilient contact  25 . 
   The edge  12 S of the retaining portion  22  at the opening of the locking hole  19  in the bottom plate  12  contacts the lock  52  to retain the terminal fitting T. The edge  12 S is displaced inwardly of the rectangular tube  10 . Thus, a larger engaging margin can be ensured as compared to a case where only the thickness of the plate serves as an engaging margin. 
   The retaining portion  22  is displaced inwardly of the rectangular tube  10  while the part of the edge  12 S of the bottom plate  12  is held substantially faced in a direction to substantially oppose the lock  52 , and a boundary between the lower surface of the bottom plate  12  and the edge  12 S is well defined angle. Thus, even if an external force acts on the terminal fitting T in withdrawing direction, there is no likelihood that the lock will slip and disengage from the retaining portion as in the case where the boundary between the lower surface of the bottom plate and the end surface is a curve. 
   If a degree of downward deformation of the resilient contact piece  25  becomes larger than the one in a normal contact state of the resilient contact  25  with the tab  54  when the tab  54  is inserted, a portion of the resilient contact  25  corresponding to the contact point  29  contacts the retaining portion  22  from above and prevents the resilient contact  25  from deforming beyond its resiliency limit. The retaining portion  22  retains the terminal fitting T and also prevents excessive deformation of the resilient contact  25 . Thus, the shape of the terminal fitting T can be simplified as compared to a case where an excessive deformation preventing portion for exclusive use is provided in addition to the retaining portion. 
   External matter that intrudes through the locking hole  19  could push the resilient contact  25  up from below. However, the front projections  30 F contact the bottom edge of the front locking plate  15 F and the edge of the front locking hole  18 F from below, and the rear projections  30 R contact the bottom edge of the rear locking plate  15 R and the edge of the rear locking hole  18 R from below to prevent the resilient contact  25  from being displaced up towards the tab entrance space  32 . Further, the locking plates  15 F,  15 R and the locking holes  18 F,  18 R are arranged at positions before and behind the locking hole  19 . Thus, there is no likelihood that the resilient contact  25  will incline forward and/or backward upon receiving a pushing force from external matter. As a result, the bend  26 , which is the supporting point of resilient deformation of the resilient contact  25 , will not be deformed plastically. 
   The front locking plate  15 F and the front locking hole  18 F located before the locking hole  19  are in the vicinity of the contact point  29  of the resilient contact  25  with the tab  54 , even if an area of the resilient contact  25  other than the bend  26  is deformed. Thus, there is no likelihood of changing the position of the contact point  29 . Therefore, the resilient contact  25  can contact the tab  54  with a proper contact pressure. 
   A rear displacement preventing portion (rear locking plate  15 R and the rear locking hole  18 R) is behind the locking hole  19  and near the free end  25 R of the resilient contact  25 . Thus, an interval along forward and backward directions between a front displacement preventing portion (front locking plate  15 F and front locking hole  18 F) and the rear displacement preventing portion (rear locking plate  15 R and rear locking hole  18 R) is longer than a case where the rear displacement preventing portion is closer to the supporting point of resilient deformation than to the free end. Accordingly, a degree of deformation of the resilient contact  25  when the resilient contact piece  25  is deformed between the front and rear displacement preventing portions by external matter can be suppressed, and the resilient contact  25  is unlikely to deform plastically between the front and rear displacement preventing portions. 
   The bottom plate  12  has the locking hole  19  for exposing the resilient contact  25  to the outside of the rectangular tube  10 , but the right side plate  13 R is formed with the intrusion restricting portion  21  close to the resilient contact  25  and located within the opening area of the locking hole  19 . Thus, the intrusion of external matter into the locking hole  19  can be restricted by the intrusion restricting portion  21 , which in turn prevents the interference of external matter with the resilient contact  25 . 
   The intrusion restricting portion  21  is outside a deformation space for the resilient contact  25  with respect to the width direction. Thus, the interference of the resilient contact  25  and the intrusion restricting portion  21  can be avoided. Accordingly, the contact reliability of the tab  54  and the resilient contact  25  is ensured without hindering the resilient deformation of the resilient contact  25 . 
   The widthwise center of the resilient contact  25  is deviated from that of the rectangular tube  10 . This means the presence of a dead space between the resilient contact  25  and the right side plate  13 R, which is a side plate more distant from the resilient contact  25 . However, the intrusion restricting portion  21  is in this dead space and uses the dead space effectively. 
   The locking hole  19  is formed over substantially the entire width of the rectangular tube  10  and the exposure of the bottom end surfaces of the left and right side plates  13 L,  13 R of the rectangular tube  10  in the opening area of the locking hole  19 . The bottom end of the right side plate  13 R facing the locking hole  19  is embossed to project inward, thereby forming the intrusion restricting portion  21 . The stamping or embossing forming method is easily workable as compared to cutting and bending. Therefore, a processing cost can be reduced. 
   The locking plates  15 F,  15 R extend from the extending of the ceiling plate  14  towards the bottom plate  12  substantially along the inner surface of the right side plate  13 R, and the projections  30 F,  30 R at the right edge of the resilient contact  25  are brought substantially into contact with the bottom edges of the locking plates  15 F,  15 R to restrict displacement of the resilient contact  25  towards the tab entrance space  32 . Thus, it is not necessary to form locking holes in the right side plate  13 R and there is no reduction in the strength of the right side plate  13 R or the rectangular tube  10  can be avoided. 
   The widthwise center of the inner space of the rectangular tube  10  where the resilient contact  25  is accommodated is deviated laterally from the widthwise center of the rectangular tube  10  because of the presence of the locking plates  15 F,  15 R. The resilient contact  25  would have to be narrowed by as much as this deviation if the resilient contact  25  and the rectangular tube  10  were to have their widthwise centers at the same widthwise position. However, a dead space is left at the side opposite the locking plates  15 F,  15 R in the inner space of the rectangular tube  10 , and the widthwise center of the resilient contact  25  is deviated to the side opposite to the locking plates  15 F,  15 R. Therefore, a large width can be ensured for the resilient contact  25  and the dead space in the inner space of the rectangular tube  10  is minimized. 
   The pressing portion  38  can be brought into contact with the upper edge of the front locking plate  15 F from above by extending towards the ceiling plate  14 . Additionally, the recess  37  is formed at the extending edge of the right side plate  13 R, and the front locking plate  15 F has its upward or outward displacement prevented by the pressing portion  38 . Thus, a displacement of the resilient contact  25  towards the tab entrance space  32  is prevented. 
   The upper edge of the front locking plate  15 F is recessed to form the recess  37 , and the pressing portion  38  is accommodated in the recess  37 . Thus, there is no step between the upper surface of the ceiling plate  14  and that of the pressing portion  38  on the upper surface of the rectangular tube  10 . 
   The pressing portion  38  formed at the upper edge of the right side plate  13 R prevents an upward or outward displacement of the extending edge of the ceiling plate  14 . The pressing portion  38  is accommodated in the recess  37 . Thus, the height of the rectangular tube  10  is reduced by the absence of the step between the upper surface of the ceiling plate  14  and that of the pressing portion  38  on the upper surface of the rectangular tube  10 . 
   The front locking plate  15 F is formed with the recess  37  and extends substantially along the inner surface of the right side plate  13 R. Thus, the front locking plate  15 F reinforces the right side plate  13 R, which in turn enhances the strength of the entire rectangular tube  10 . 
   The receiving plate  35  extends from the front edge of the right side plate  13 R substantially at a right angle and towards the resilient contact  25 . Additionally at least part of the extending edge of the receiving plate  35  facing the tab entrance space  32  is in an area between the right side plate  13 R and the resilient contact  25  along the width direction. Furthermore, the probe P is brought into contact with the receiving plate  35 . Thus, a contact area of the probe P along the width direction is wider than the thickness of the right side plate  13 R and the probe P can be brought securely into contact with the rectangular tube portion  10  even if displaced in the width direction. In addition, at least the part corresponding to the tab entrance space  32  along the height direction is in the area between the right side plate  13 R and the resilient contact  25  along the width direction. Therefore, the receiving plate does not interfere with the tab  54  entering the tab entrance space  32 . 
   The receiving plate  35  is formed over substantially the entire height of the right side plate  13 R to increase the touchable area of the probe P along the height direction. Thus, a degree of freedom in designing is increased for setting the arrangement of the work openings  56  as the entrance openings for the probe P in the housing  50 . 
   The widthwise center of the resilient contact piece could be made to coincide with that of the rectangular tube. In this case, the width of clearances between the side plates and the resilient contact would be substantially half the difference between the width of the rectangular tube and that of the resilient contact. Contrary to this, the widthwise center of the resilient contact  25  is deviated from that of the rectangular tube  10  in this embodiment. Thus, the width of the wider clearance between the side plate and the resilient contact  25  is larger than half the difference between the width of the rectangular tube  10  and that of the resilient contact  25 . Accordingly, a large extending distance from the right side plate  13 R can be ensured for the receiving plate  35 . 
   The front end surface  35 F of the receiving plate  35  is before the front end of the resilient contact  25 . Thus, there is no likelihood of the probe P interfering with the resilient contact  25  even if part of the probe P does not touch the receiving plate  35 . 
   The slanted guide surface  36 R is formed at the extending edge of the receiving plate  35  and corrects the position of the tab  54  towards the tab entrance space  32  if the tab  54  is displaced towards the receiving plate  35 . Accordingly, there is no likelihood that the tab  54  will strike the receiving plate  35 . 
   The base portion  33  is formed narrower than the bottom plate  12  by cutting away the left and/or right edge(s) close to the front end of the bottom plate  12 , and the bend  26  at the front end of the resilient contact  25  is connected with the front end of the base portion  33 . The base portion  33  has the bulge  34  bulging out from the side edge of the base portion  33  toward the right side plate  13 R of the rectangular tube  10 . The bulge  34  narrows an area of the opening between the base portion  33  and the right side plate  13 R and substantially prevents intrusion of external matter into the rectangular tube  10  through this opening. Further, the base portion  33  is wider and is reinforced by forming the bulge  34 . Thus, a deformation of the base portion  33  resulting from the interference with external matter can be prevented even if the resilient contact  25  is narrow. 
   The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are also embraced by the technical scope of the present invention as defined by the claims. Beside the following embodiments, various changes can be made without departing from the scope and spirit of the present invention as defined by the claims. 
   One displacement restricting portion is near the contact point in the foregoing embodiment. However both displacement restricting portions may be distant from the contact point according to the invention. 
   One displacement restricting portion is near the free end of the resilient contact in the foregoing embodiment. However, both displacement restricting portions may be distant from the free end according to the invention. 
   The projections project from the left and right edges of the resilient contact for contacting the displacement restricting portions in the foregoing embodiment. However, the projections may project only from one edge. 
   The right projections are brought into contact with the locking plates in the foregoing embodiment. However they may be brought into contact with the opening edges of the locking holes formed in the side plate. 
   The contact is located before the locking hole in the foregoing embodiment. However, the invention is also applicable to terminal fittings in which a contact point is at a position substantially corresponding to a locking hole and/or at a position substantially behind the locking hole. 
   The resilient contact and the displacement restricting portions are not in contact unless the resilient contact is in contact with the tab in the foregoing embodiment. However, they may be in contact even if the resilient contact and the tab are not in contact according to the invention. 
   The projections on the resilient contact are brought into contact with the displacement restricting portions in the foregoing embodiment. However, the lateral edges of the resilient contact may contact the displacement restricting portions without providing any projection according to the invention. 
   The resilient contact is supported on or at the bottom plate at or close to the front end thereof in the foregoing embodiment. However, the resilient contact may be supported at the rear end bottom plate. 
   The widthwise center of the resilient contact is deviated from that of the rectangular tube in the foregoing embodiment. However, the invention is also applicable to terminal fittings in which the widthwise centers of a resilient contact and a rectangular tube substantially coincide. 
   The widthwise center of the locking hole coincides with that of the rectangular tube in the foregoing embodiment. However, the widthwise center of the locking hole may deviate from that of a rectangular tube. 
   The locking hole is formed over substantially the entire width of the rectangular tube in the foregoing embodiment. However, the invention is also applicable to a case where the locking hole is narrower than the tube. 
   The tube described above has a substantially rectangular cross-section. However, the invention is equally applicable to tubes with other shapes, particularly substantially polygonal (triangular, pentagonal, hexagonal, etc.) shapes or substantially round, circular, oval, elliptical or the like shapes. 
   The projections are formed on the lateral edges of the resilient contact and are brought into contact with the locking plate in the foregoing embodiment. However, the lateral edges of the resilient contact may be brought into contact with the locking plates without forming any projection on the lateral edges of the resilient contact according to the invention. 
   The locking plate is pressed from above by the pressing portion in the foregoing embodiment. However, there may be no pressing portion. 
   The upper surface of the pressing portion is substantially flush with that of the ceiling plate in the foregoing embodiment. However, it may be higher or lower than the upper surface of the ceiling plate. 
   The locking plates are at front and rear positions and the resilient contact is brought into contact with the locking plates at two front and rear positions in the foregoing embodiment. However, the resilient contact may be contact the locking plate at one position or at three or more positions.