Abstract:
One  20  of a pair of connector housings  10, 20  connectable with each other is provided with a slider  40 . The other connector housing  10  is provided with main follower pins  17  and auxiliary follower pins  18  located at different positions from the main follower pins  17 . The slider  40  is formed with main cam grooves  44  for guiding the main follower pins  17  until the connection of the two connector housings  10, 20  is completed and auxiliary cam grooves  48  engageable with the auxiliary follower pins  18  at a desired timing within a period from an intermediate stage of the connection of the two connector housings  10, 20  to a completing timing of the connection.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a connector and a connector assembly connectable and separable using a cam mechanism. 
   2. Description of the Related Art 
   U.S. Pat. No. 6,113,407 discloses a slider type connector with first and second housings that are connectable with each other. A slider is mounted on the first housing and is movable in a direction that intersects a connecting direction of the housings. The slider is formed with cam grooves and the second housing includes follower pins that are engageable with the cam grooves of the slider. The slider initially is at a retracted position, and the follower pins face the entrances of the cam grooves. The slider then is moved forward. As a result, the follower pins are displaced along the cam grooves and the two housings are connected. 
   The above-described slider-type connector has a plurality of pairs of cam grooves and follower pins are arranged along advancing and retracting directions of the slider. Thus, the length of the slider is restricted. As a result, the length of each cam groove invariably becomes shorter and an angle of inclination of each cam groove to the connecting direction becomes larger. Specifically, there is a shorter displacement of the slider from the start of the connection, where the follower pins are at the entrances of the cam grooves, to the end of the connection, where the follower pins are at the back ends of the cam grooves. Consequently, the pushed state of the slider cannot be confirmed easily by the eyes and a larger force is required for the connection. Accordingly, an operator may misunderstand that the properly connected state has been reached even though the two housings have not yet reached a proper connection position. 
   Some slider-type connectors have only one pair of the cam grooves and the follower pins formed along the advancing and retracting directions of the slider. Thus, the cam groove can be long and the angle of inclination of the cam groove to the connecting direction can be smaller. An operation force required for the connecting operation is smaller in this type of the connector. However, a connector with only one pair of cam grooves and follower pins can cause the housings to shake and rotate about the follower pin while being properly connected. 
   Both types of connectors have advantages and disadvantages, and there has been a demand for a solution to solve these problems rationally. 
     FIG. 36  shows a connector with a slider  3  formed with cam grooves  2 . The slider is mounted on a first housing  1  that is connectable with a second housing (not shown). The slider  3  can advance and retract on the first housing  1  in a direction intersecting a connecting direction of the two housings. Follower pins are provided at the second housing (not shown) and are engageable with the cam grooves  2 . The cam grooves  2  are inclined toward a backside with respect to the connecting direction (identified by an arrow in  FIG. 36 ) as they extend from starting ends  2 A toward terminus ends  2 B. The two housings initially are fit lightly with the slider  3  at a retracted position to bring the follower pins to the entrances of the cam grooves  2 . The slider  3  then is advanced. As a result, the follower pins are displaced toward the terminus ends  2 B in the cam grooves  2  and the housings are pulled towards each other. The two housings are connected properly when the follower pins reach the terminus ends  2 B of the cam grooves  2 . 
   The connector of this type is subjected to a considerable resistance, particularly, at a final stage of the connection of the two housings while the slider  3  is pushed. Thus, a pushing operation may be interrupted halfway and the two housings may be left only partly connected. Further, two properly connected housings may be separated and the slider  3  may be returned to the retracted position if forces act on the housings in separating directions. 
   The invention was developed in view of the above problems and an object thereof is to provide a connector and connector assembly that have can be connected easily, stably held connected without shaking and/or be prevented from being left partly connected. 
   SUMMARY OF THE INVENTION 
   The invention is directed to a connector with first and second housings that are connectable with each other. A slider or other movable member formed with a cam means is mounted on the first housing for movement in a direction intersecting a connecting direction of the two housings. The second housing has a mating cam means that is engageable with the cam means of the movable member. The mating cam means is displaced with respect to the cam means during a period from an initial stage of the connection of the two housings substantially to the completion of the connection as the movable member is moved. As a result, the two housings are connected or separated as the movable member is moved. The connector further includes a holding mechanism at a position different from the position where the mating cam means is engaged with the cam means. The holding mechanism functions for locking the first housing together with the second housing and/or the movable member. The holding mechanism functions in a period from an intermediate stage of the connection of the two housings substantially to the completion of the connection. 
   The cam means may be a cam groove and the mating cam means may be a follower pin. The follower pin is aligned substantially with the entrance of the cam groove at the initial stage of connecting the housings. The movable member then is operated in this state, for example, by advancing the slider. The connection of the housings proceeds until the housings reach a properly connected state. The holding mechanism acts during the period from the intermediate stage of connecting the housings to the completion of the connection. A locking position of the holding mechanism is different from a position of locking by the follower pin and the cam groove. Thus, the two housings are held in a stable manner that will prevent rotation or other movement after the connection is completed. Additionally, an operation force can be low because the single cam groove can be long and can have a moderate angle of inclination. 
   The holding mechanism may include an auxiliary follower pin on the second housing at a location spaced from the main follower pin. The holding mechanism may also include an auxiliary cam groove that is disposed on the movable member at a location for engaging the auxiliary follower pin within the period from the intermediate stage of connecting the housings to the completion of the connection. 
   Accordingly, the main follower pin first aligns substantially with the main cam groove. The movable member then is moved so that the housings are moved towards one another. The auxiliary follower pin enters the auxiliary cam groove in the process of connecting the housings to attain the locked state at the desired time between the intermediate stage of the connection and the completion of the connection. As a result, the housings are prevented from rotating about the main follower pin while being connected with each other. 
   The auxiliary cam groove preferably is arranged to overlap the main cam groove with respect to an operating direction of the movable member. Accordingly, the main cam groove can have a long length along the operating direction of the movable member. As a result, a force required to operate the movable member is low. 
   An alternate connector according to the invention also has first and second housings that are connectable with each other. A movable member formed with a cam groove is mounted on the first housing for movement in a direction intersecting a connecting direction of the two housings. The second housing has a follower pin that is engageable with the cam groove of the movable member. The follower pin is displaced from the starting end of the cam groove to the terminus end of the cam groove as the movable member is operated. As a result, the two housings are connected or separated as the movable member is moved. A returning portion is formed near the terminus end of the cam groove and is adapted to displace and/or allow the displacement the housings in separating directions as the follower pin is moved toward the terminus end in the cam groove. Accordingly, forces that act on the housings in separating directions at the final stage of connecting the housings will act to pull the slider. As a result the slider is prevented from stopping at an intermediate position, and the housings are prevented from being left only partly connected. Additionally, forces exerted to separate the properly connected housings only result in the follower pin being pressed against the edge of the cam groove near the terminus end. Thus, the follower pin pushes the slider back to prevent the two housings from being separated. 
   The cam groove preferably comprises a substantially straight portion that is inclined with respect to the operating direction of the movable member. The returning portion preferably is inclined to the operating direction in a direction opposite to the inclination of the substantially straight portion. Additionally, the cam groove preferably has a peaked portion near the returning portion. An angle of inclination of a front edge of the returning portion preferably is in a range from about 10° to about 5°, and most preferably about 7° to the operating direction of the operable member. 
   Biasing means preferably are provided for generating forces between the housings to separate the housings in case a connection is interrupted before the housings reach their properly connected state. 
   A seal preferably is provided to achieve an airtight closure of an inner space between the two properly connected housings. Accordingly, inner pressure increases as the two housings are connected more deeply. Thus, the slider is pulled with a strong force when the follower pin enters the returning portion at the final stage of the connection, and the slider is prevented from stopping at an intermediate position. 
   An inner pressure of the inner space preferably increases gradually to create biasing forces on the housings in separating directions as the two housings are brought closer to each other. 
   The biasing forces brought about by the inner pressure of the housings urge the housings in separating directions to pull the movable member when the follower pin has reached the returning portion. Thus, resistance on the movable member suddenly decreases and the movable member is moved to the advanced position with the addition of an inertial force. 
   These and other features and advantages of the invention will become more apparent upon reading the following detailed description of preferred embodiments and accompanying drawings. Even though embodiments are described separately, single features may be combined to additional embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of male and female housings according to a first embodiment of the invention before being connected. 
       FIG. 2  is a plan view of the male and female housings before being connected. 
       FIG. 3  is a longitudinal section of the male and female housings before being connected. 
       FIG. 4  is a front view of the male housing. 
       FIG. 5  is a front view of the female housing. 
       FIG. 6  is a plan view of the female housing. 
       FIG. 7  is a side view of the female housing. 
       FIG. 8  is a rear view of the female housing. 
       FIG. 9  is a bottom view of the female housing. 
       FIG. 10  is a bottom view of a slider. 
       FIG. 11  is a longitudinal section of the slider. 
       FIG. 12  is a side view of the slider. 
       FIG. 13  is a plan view in section showing an initial stage of the connection of the male and female housings. 
       FIG. 14  is a plan view in section showing an intermediate stage of the connection of the male and female housings. 
       FIG. 15  is a plan view partly in section showing a completed state of the connection of the male and female housings. 
       FIG. 16  is a plan view of male and female housings according to a second embodiment of the invention before being connected. 
       FIG. 17  is a bottom view of a slider. 
       FIG. 18  is a plan view in section showing an initial stage of the connection of the male and female housings. 
       FIG. 19  is a plan view in section showing an intermediate stage of the connection of the male and female housings. 
       FIG. 20  is a plan view partly in section showing a completed state of the connection of the male and female housings. 
       FIG. 21  is a plan view of male and female housings according to a third embodiment of the invention before being connected. 
       FIG. 22  is a longitudinal section of the male and female housings before being connected. 
       FIG. 23  is a front view of the male housing. 
       FIG. 24  is a front view of the female housing. 
       FIG. 25  is a plan view of the female housing with a slider at an advanced position. 
       FIG. 26  is a side view of the female housing with the slider mounted at the advanced position. 
       FIG. 27  is a rear view of the female housing. 
       FIG. 28  is a bottom view of the slider. 
       FIG. 29  is a longitudinal section of the slider. 
       FIG. 30  is a partial enlarged section showing a state where a locking piece is engaged with a locking hole. 
       FIG. 31  is a plan view partly in section showing an initially connected state of the male and female housings. 
       FIG. 32  is a plan view partly in section showing a state where the male and female housings are most deeply connected. 
       FIG. 33  is a partial enlarged plan view showing a portion of a cam groove near a terminus end. 
       FIG. 34  is a plan view partly in section showing a properly connected state of the male and female housings. 
       FIG. 35  is a longitudinal section showing the properly connected state of the male and female housings. 
       FIG. 36  is an exploded perspective view of a prior art connector. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 15  show a first embodiment of a connector according to the invention. As shown most clearly in  FIGS. 1 to 3 , the connector is has a male housing  10  and a female housing  20  that are connectable with each other. The connector also includes a slider  40  mounted on the female housing  20 . 
   The male housing  10  is made e.g. of a synthetic resin and is formed such that a small receptacle  12  projects from the front surface of a main body  11  in the form of a laterally long block, as shown in  FIG. 4 . Four larger male terminals  14 L project in a 2×2 array in a right end area of the back surface of the small receptacle  12  of the male housing  10  when viewed from the front, and smaller male terminals  14 S project in three rows in a remaining area. 
   The female housing  20  is made e.g. of a synthetic resin and has a substantially flat tower  21  and a large receptacle  22  that surrounds the tower  21 . The tower  21  can fit in the small receptacle  12  and the large receptacle  22  can fit on the outer surface of the small receptacle  12 . Covers  23  are formed above and below the upper and bottom surfaces of the large receptacle  22  and are spaced apart by a specified distance, as shown in  FIG. 3 , and insertion paths  24  are defined between both covers  23  and the upper and bottom surfaces of the large receptacle  22 . The insertion paths  24  are open at their left and right sides, and are substantially closed at front and rear sides. 
   Four large cavities  27 L are formed inside the tower  21 , at a left area of the female housing  20  when viewed from the front (see  FIG. 5 ). The large cavities  27 L are configured for receiving the large female terminals  26 L (see chain line in  FIG. 5 ). The large cavities  27 L are formed in a 2×2 array to correspond to the large male terminals  14 L. Small cavities  27 S are formed in a remaining area of the tower  21  and are configured to receive the small female terminals  26 S (see chain line in  FIG. 3 ). The small cavities  27 S are disposed in e.g. three rows to correspond to the small male terminals  14 S. 
   A large resiliently deformable lock  28 L is provided in the bottom surface of each large cavity  27 L for partly locking the large female terminal  26 L. Similarly, a small resiliently deformable lock  28 S is provided in the ceiling of each small cavity  27 S for partly locking the small female terminal  26 S. 
   A retainer insertion hole  30  opens in the left and right surfaces of the tower  21 , and a retainer  31  is insertable into the retainer insertion hole  30  for doubly locking the large and small female terminals  26 L,  26 S (see  FIG. 3 ). 
   The retainer  30  can be held at a partial locking position where locking projections  32  (only those for the smaller female terminals  26 S are shown in  FIG. 3 ) are located before the corresponding cavities  27 L,  27 S. The female terminals  26 L,  26 S then are inserted into the corresponding cavities  27 L,  27 S and are locked partly by the locks  28 L,  28 S. The retainer  31  then is pushed to a full locking position. Thus, the locking projections  32  of the retainer  30  enter the cavities  27 L,  27 S and engage the female terminals  26 L,  26 S that have been inserted into the cavities  27 L,  27 S. Accordingly, the female terminals  26 L,  26 S are locked redundantly by the retainer  31  and will not come out. 
   The slider  40  is made e.g. of a synthetic resin similar to the female housing  20 , but this synthetic resin material preferably has a color different from the color of the female housing  20 . As shown in  FIGS. 10 to 12 , the slider  40  has a substantially gate or U-shape with two slidable plates  41  coupled by a coupling plate  42 . The slider  40  is mounted by inserting the slidable plates  41  laterally into the upper and lower insertion paths  24  of the female housing  20 . 
   Each slidable plate  41  has a main cam groove  44  that extends from the leading end of the front edge of the slidable plate  41  substantially to a longitudinal center while being gradually inclined toward the rear edge. The inclination of the main cam groove  44  is slightly steeper at a starting end  44 A, and an entrance  45  of the main cam groove  44  is open at a substantially right angle to the front edge of the slidable plate  41 . The entrance  45  is substantially continuous with the starting end  44 A. 
   An auxiliary cam groove  48  is formed in a longitudinal middle portion of each slidable plate  41  and behind the main cam groove  44  with respect to a pushing direction PD of the slider  40 . The auxiliary cam groove  48  extends substantially parallel with the main cam groove  44 . An entrance  49  of the auxiliary cam groove  48  makes a wider opening at the front edge of the slidable plate  41  as compared to the main cam groove  44 , and a starting end  48 A of the auxiliary cam groove  48  near the entrance  49  is more moderately inclined than the starting end  44 A of the main cam groove  44 . The auxiliary cam groove  48  is arranged such that the starting end  48 A thereof overlaps the main cam groove  44  along a pushing direction PD of the slider  40 . 
   Main follower pins  17  project from widthwise middle positions near the front edges of the upper and lower surfaces of the small receptacle  12  as shown in  FIGS. 1 to 4  and are engageable with the corresponding main cam grooves  44 . 
   An auxiliary follower pin  18  projects at a position obliquely back from each main follower pin  17  and is received into the corresponding auxiliary cam groove  48 . The auxiliary follower pins  18  are more distant from an engaging surface of the male housing  10  than the main follower pins  17 . Thus, the auxiliary follower pins  18  reach the entrances  48 A of the auxiliary cam grooves  48  at a more progressed stage of the connection of the housings  10 ,  20 . 
   An introducing hole  47  is formed substantially at a widthwise middle of a front plate  24 A of each of the upper and lower insertion paths  24  of the female housing  20  for permitting entry of the corresponding main follower pin  17 . Similarly, an introducing hole  46  is formed at one side of each introducing hole  47 , as shown in  FIG. 5 , for permitting entry of the corresponding auxiliary follower pin  18 . Further, escape grooves (not shown) are formed substantially at a widthwise middle of the large receptacle  22  and are substantially continuous with the corresponding introducing hole  47 . Similarly, escape grooves  29  are formed at one side of the former escape groove substantially continuous with the corresponding introducing hole  46 . The escape grooves receive the main and auxiliary follower pins  17  and  18 . 
   A grip  50  is formed on the outer surface of the base end of each slidable plate  41  of the slider  40  and is used to manipulate, insert and withdraw the slider  40 . As shown in  FIGS. 10 and 11 , a resiliently deformable locking piece  52  is formed at one grip  50  and a locking claw  53  is formed at the leading end thereof. 
   An escape groove  55  is formed at the left end of the upper cover  23  of the female housing  20  when viewed from the front as shown in  FIG. 6 , and is configured for receiving the grip  50  of the slider  40 . Similarly, an escape groove  55 A is formed at the left end of the lower cover  23  as shown in  FIG. 9  for receiving the locking piece  52 . A locking hole  56  is formed at the leading end of the escape groove  55 A for receiving the locking claw  53  of the locking piece  52 . 
   A first partial locking piece  57  is formed towards the rear edge of each slidable plate  41  of the slider  40  at a position corresponding to a substantially longitudinal middle of the main cam groove  44 , as shown in  FIGS. 10 and 11 . The partial locking pieces  57  cantilever toward the base ends of the slidable plates  41  and are resiliently deformable. Protrusions  58  are formed on the outer surfaces of the projecting ends of partial locking pieces  57 . 
   A long groove  60  is formed in a substantially longitudinal middle of each cover  23  of the female housing  20  along a rear edge portion thereof, as shown in  FIG. 2 . The protrusions  58  of the partial locking pieces  57  fit into the long grooves  60 . The opposite ends of each long groove  60  are closed at the outer surface, and locking holes  61  are formed in the inner surfaces of the closed portions for receiving the protrusion  58  of the corresponding partial locking piece  57 , as shown in  FIG. 8 . 
   The slidable plates  41  of the slider  40  are inserted into the insertion paths  24  of the female housing  20  from the left side of  FIG. 2 . The protrusions  58  of the partial locking pieces  57  then drop into the locking holes  61  at the left ends of the long grooves  60  in  FIG. 2  to hold the slider  40  at a retracted position. At this retracted position, the entrances  45  of the main cam grooves  44  align with the introducing holes  47  of the female housing  20  as shown in  FIG. 2 . 
   The slider  40  is pushed in the pushing direction PD to an advanced position where the coupling plate  42  contacts the left surface  20 A of the female housing  20 . At this advanced position, the locking claw  53  of the locking piece  52  fits into the locking hole  56  of the cover  23 , as shown in  FIG. 9 , to lock the slider  40 . 
   Each of the upper and lower covers  23  of the female housing  20  is formed with a confirmation window  65  for visually and/or automatically confirming whether the slider  40  is at the retracted position. Specifically, each confirmation window  65  has a substantially rectangular shape and is at a position slightly before the long groove  60  and in the longitudinal center of the cover  23  as shown in  FIG. 2 . 
   The back-side edge of the starting end  44 A of the main cam groove  44  of each slidable plate  41  is in the entire corresponding confirmation window  65  only when the slider  40  is at the retracted position. Part of each main cam groove  44  is in the confirmation window  65  when the slider  40  is before the retracted position. 
   The coupling plate  42  of the slider  40  also has a vertically long recess  70  at the back side substantially at a middle position with respect to height direction as shown in  FIG. 1 . The recess  70  provides an alternate means for detecting whether or not the slider  40  has reached the advanced position by hand feeling. 
   A projection  72  is formed substantially at a middle position with respect to the height direction at the back side of the left surface  20 A of the female housing  20 , as shown in  FIG. 8 . The projection  72  is dimensioned to fit into the recess  70  of the slider  40 . A projecting height of the projection  72  substantially equals the thickness of the coupling plate  42 . The coupling plate  42  contacts the left surface  20 A of the female housing  20  when the slider  40  reaches the advanced position. Thus, the projection  72  fits into the recess  70  and a projecting surface  72 A of the projection  72  is substantially flush with an outer surface  42 A of the coupling plate  42 , as shown in  FIG. 15 . 
   The female terminals  26 L,  26 S are inserted into the cavities  27 L,  27 S of the female housing  20  and are locked doubly the retainer  31 . 
   The slider  40  also is mounted into the female housing  20  in advance. The slidable plates  41  of the slider  40  are inserted into the insertion paths  24  from the left side of the female housing  20  and the slider  40  is pushed in one stroke along the pushing direction PD and into the advanced position. As shown in  FIG. 9 , at least part of the locking claw  53  of the locking piece  52  fits resiliently into the locking hole  56  to hold the slider  40  at the advanced position. 
   The female housing  20  is transported to a site of a connecting operation with the male housing  10  with the slider  40  mounted at the advanced position. Prior to the connection of the two housings  10 ,  20 , the slider  40  is returned towards or to the retracted position. More particularly, the upper and lower grips  50  of the slider  40  are held e.g. by fingers. The locking piece  52  then is deformed resiliently in to cause the locking claw  53  to come out of the locking hole  56 , thereby canceling the locked state. Accordingly, the slider  40  can be pulled while the grips  50  are held. In the meantime, the partial locking pieces  57  are returned along the long grooves  60 . The slider  40  stops being pulled when the protrusions  58  fall into the locking holes  61 . Thus, the slider  40  is held at the retracted position shown in  FIG. 2 . The confirmation window  65  enables a check to be performed for determining whether the slider has been returned properly to the retracted position. 
   The male housing  10  can be fit at least partly into the large receptacle  22  of the female housing  20 , as indicated by an arrow in  FIG. 2 , after the slider  40  has been returned to the proper retracted position. The main follower pins  17  of the male housing  10  then enter the entrances  45  of the main cam grooves  44  through the introducing holes  47 . The male housing  10  is pushed further so that the main follower pins  17  push the back edges (upper edges in  FIG. 13 ) of the starting ends  44 A of the cam grooves  44 , as shown in  FIG. 13 . As a result, the slider  40  is moved by a specified distance along the inclination of the starting ends  44  towards the advanced position. As a result, the main follower pins  17  enter the main cam grooves  44  and are caught by the front edges of the starting ends  44 A to prevent disengagement of the male housing  10 . 
   The connection of the two housings  10 ,  20  proceeds sufficiently for the main follower pins  17  to be caught by the front edges of the starting ends  44 A of the main cam grooves  44 . At this time, the auxiliary follower pins  18  are located near the entrances  49  of the auxiliary cam grooves  48  (see  FIG. 13 ). 
   The slider  40  then is pushed in the pushing direction PD toward the advanced position as indicated by an arrow in  FIG. 13 . Thus, as shown in  FIG. 14 , the male housing  10  is pushed gradually into the female housing  20  mainly due to forces exerted on the front edges of the main cam grooves  44  on the follower pins  17 . In the meantime, the auxiliary follower pins  18  move in the auxiliary cam grooves  48 . The male and female housings  10 ,  20  are connected properly when the auxiliary follower pins  18  are moved to terminus ends  48 B of the auxiliary cam grooves  48 . 
   The locking claw  53  of the locking piece  52  fits into the locking hole  56 , as shown  FIG. 9 , when the slider  40  is pushed sufficiently in the pushing direction PD to the advanced position. Simultaneously, the two housings  10 ,  20  are locked in their properly connected state. A part of the outer surface  42 A of the coupling plate  40  near the recess  70  can be touched by hand to confirm whether the slider  40  has been pushed properly to the advanced position. 
   The locking achieved by the main follower pins  17  and the auxiliary follower pins  18  in the properly connected state prevents the two housings  10 ,  20  from shaking in a rotating direction or being displaced pivotally with respect to each other. The connection of the two housings  10 ,  20  is guided by the engagement of the main follower pins  17  and the main cam grooves  44 , and the guide brought about by the engagement of the auxiliary follower pins  18  and the auxiliary cam grooves  48  is only secondary. Accordingly, the auxiliary cam grooves  48  can be shorter than the main cam grooves  44  and can be so arranged to overlap the main cam grooves  44  along the pushing direction PD. Thus, the length of the main cam grooves  44  can be longer and the inclination of the main cam grooves  44  can be more moderate as compared to a case where the auxiliary cam grooves  48  do not overlap the main cam grooves  44 . Therefore, operation forces used to advance and retract the slider  40  are low. 
   A connector of a second embodiment shown in  FIGS. 16 to 20  has substantially the same construction as that of the first embodiment, but the positions of auxiliary cam grooves and auxiliary follower pins differ from those of the first embodiment. Hereinafter, no repeated description is given for elements that have the same or similar construction as the first embodiment. 
   A slider  40  has a gate or U-shape with two slidable plates  41  coupled by a coupling plate  42 . Main cam grooves  44  similar to those of the first embodiment are formed in both slidable plates  41 . As shown in  FIG. 17 , auxiliary cam grooves  68  are formed behind the main cam grooves  44  with respect to a connecting direction CD of the two housings  10 ,  20 . Each auxiliary cam groove  68  has a starting end at an end of the slidable plate  41  opposite from the coupling plate  42 , and extends slightly oblique to a retracting direction of the slider  40  between the starting end and a terminus end  68 B. 
   The male housing  10  has a small receptacle  12 , and a main follower pin  17  stands substantially at a widthwise middle position near the front edge of each of the upper and lower surfaces of the small receptacle  12 . The main follower pins  17  are engageable with the corresponding main cam grooves  44 . An auxiliary follower pin  19  projects at a position obliquely forward from each main follower pin  17  as shown in  FIG. 16  and is engageable with the corresponding auxiliary cam groove  68  at a final stage of the connection of the two housings  10 ,  20 . 
   Introducing holes  47  and  49  are formed in a front plate  24 A of each of the upper and lower insertion paths  24  of the female housing  20 . The introducing holes  47  permit entry of the corresponding main follower pins  17  and the introducing holes  69  permit entry of the corresponding auxiliary follower pin  68 . Further, escape grooves (not shown) are formed substantially at a widthwise middle of a larger receptacle  22  continuous with the corresponding introducing hole  47 . Similarly, escape grooves  33  are substantially continuous with the corresponding introducing hole  69 . These escape grooves permit the entrance of the main and auxiliary follower pins  17  and  19 . 
   The male housing  10  is fit at least partly into the larger receptacle  22  of the female housing  20  with the slider  40  at the retracted position. Thus, the main follower pins  17  of the male housing  10  enter the entrances  45  of the main cam grooves  44  through the introducing holes  47  and the escape grooves. Similarly, the auxiliary follower pins  19  enter the escape grooves  33  through the introducing holes  69 . The male housing  10  is pushed further, and thus the slider  40  moves a specified distance along the inclination of the main cam grooves  44  toward an advanced position. 
   Subsequently, the slider  40  is pushed in the pushing direction PD toward the advanced position, as indicated by an arrow in  FIG. 18 . Accordingly, the male housing  10  is drawn gradually into the female housing  20  mainly by a cam action displayed by the front edges of the main cam grooves  44  pushing the follower pins  17 , as shown in  FIG. 19 . 
   The main follower pins  17  move towards the terminus ends of the main cam grooves  44  as the slider  40  is pushed in the pushing direction PD. The auxiliary follower pins  19  enter the auxiliary cam grooves  68  in the final stage of the connection of the two housings  10 ,  20  and after the main follower pins  17  move beyond the longitudinal middles of the main cam grooves  44  (see  FIG. 19 ). The slider  40  continues to be pushed in the pushing direction PD to the advanced position. As a result, the main follower pins  17  are moved to terminus ends  44 B of the main cam grooves  44  and the auxiliary follower pins  19  are moved to the terminus ends  68 B of the auxiliary cam grooves  68 , as shown in  FIG. 20 . Consequently, the male and female housings  10 ,  20  are connected properly connected. 
   Similar to the first embodiment, the two housings  10 ,  20  are prevented from shaking in a rotating direction because the main and auxiliary follower pins  17 ,  19  of the male housing  10  and the main and auxiliary cam grooves  44 ,  68  of both the slidable plates  41  are engaged at two locking positions in the properly connected state. Additionally, the auxiliary follower pins  19  engage the auxiliary cam grooves  68  immediately before the connection of the two housings  10 ,  20  is completed. Thus, the length of the auxiliary cam grooves  68  can be even shorter than in the first embodiment and the main cam grooves  44  can be accordingly made longer. Therefore, a force required for the connecting operation is less than in the first embodiment. 
   The invention is not limited to the above described and illustrated embodiments. 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. 
   In the foregoing embodiment, a holding mechanism is formed by the auxiliary cam grooves and the auxiliary follower pins. Instead of such a cam mechanism, the holding mechanism may be a lock arm to engage a mating partner when the connection is completed. In such a case, the lock arm may be engaged between the slider and the housing or between the two housings. 
   The auxiliary grooves are formed in the slider and the auxiliary follower pins are formed on the male housing in the foregoing embodiment. However, the arrangement of the auxiliary cam grooves and the auxiliary follower pins may be reversed. 
   The slider may be mounted into or to the male housing. 
   The invention has been described with reference to a slider that is linearly movable along the pushing direction. However, the cam action could be displayed by a different movable member, such as a rotatable or pivotable lever, a movable member movable substantially along a non-linear path, etc. 
   A third embodiment of the invention is illustrated in  FIGS. 21 to 35 . As shown in  FIGS. 21 and 22 , this connector has a male housing  10  and a female housing  20  that are connectable with each other. A slider  40  is mounted in the female housing  20 . 
   The male housing  10  is made e.g. of a synthetic resin and has a main body  11  and a small receptacle  12 . The main body  11  is in the form of a wide block, and the small receptacle  12  projects from the front surface of the main body  11 , as also shown in  FIG. 23 . Four large male terminals  14 L project in a 2×2 array in a right end area of the back surface of the smaller receptacle  12  of the male housing  10  when viewed from the front, and small male terminals  14 S project in three rows in a remaining area. 
   The female housing  20  also is made e.g. of a synthetic resin and has a tower  21  and a large receptacle  22  is formed around the tower  21 . The large receptacle  22  can fit on the outer surface of the small receptacle  12  of the male housing  10  and the tower  21  can fit into the small receptacle  12 , as shown in  FIG. 24 . A seal ring  123  is mounted at a back side of the outer peripheral surface of the tower  21  and can be brought resiliently into close contact with the inner peripheral surface of the small receptacle  12 . Further, a bottomed tubular cap  124  is fit on a front part of the tower  21  to lock the seal ring  123  so as not to come out. Covers  125  are formed above and below the upper and bottom surfaces of the large receptacle  22  and are spaced apart by a specified distance. Insertion paths  126  are defined between both covers  125  and the upper and bottom surfaces of the large receptacle  22 . The insertion paths  126  are open at their left and right sides while being closed at front and rear sides. 
   Four large cavities  128 L are formed in a left area of the tower  21  when viewed from the front, as shown in  FIG. 24 , and define a 2×2 array that corresponds to the arrangement of the larger male terminals  14 L Large female terminals  127 L are accommodated in the large cavities  128 L. The large female terminals  127 L are not shown in detail, but are structurally similar to small female terminals  127 S described below. Fourteen smaller cavities  128 S are formed in each of three rows in a remaining area of the tower  21  and substantially correspond to the smaller male terminals  14 S. Small female terminals  127 S are accommodated in the small cavities  128 S. The respective cavities  128 L,  128 S have open front and rear ends, and the smaller female terminals  127 S can be stopped at their front-limit positions by the cap  124  that covers the front ends of the smaller cavities  128 S. An engaging hole  129  and terminal insertion holes  130  are formed in the front surface of the cap  124 . The engaging hole  129  engages the front ends of surrounding walls of the four larger cavities  28 L and the terminal insertion holes  130  are at positions substantially corresponding to the respective smaller cavities  28 S and permit the passage of respective smaller terminals  14 S. 
   A tubular terminal connecting portion  131  is formed at a front part of each of the large and small female terminals  127 L,  127 S, and a resilient contact piece (not shown) is inside each tubular terminal connecting portion  131 . The resilient contact piece resiliently contacts the male terminal  14 L,  14 S to establish electrical connection when a mating male terminal  14 L,  14 S is inserted into the terminal connecting portion  131  from the front. A barrel  132  is provided at a rear part of each female terminal  127 L,  127 S, and is crimped, bent or folded into connection with an end of a wire  133 . A resilient or rubber plug  134  is mounted on the end of the wire  133 . The outer circumferential surface of the rubber plug  134  can be brought resiliently into close contact with the inner circumferential surface of a rear part of the cavity  28 L,  28 S. 
   A large resiliently deformable lock  136 L is provided in the bottom surface of each larger cavity  28 L for partly locking the large female terminal  127 L. A small resiliently deformable lock  136 S similarly is provided in the ceiling surface of each small cavity  28 S for partly locking the small female terminal  127 S. A retainer insertion hole  137  is formed in each of the left and right surfaces of the tower  21 , and a retainer  138  is insertable into the retainer insertion hole  137 , as shown in  FIG. 26 , for doubly locking the large and small female terminals  127 L,  126 S. 
   The retainer  138  can be inserted into the retainer insertion hole  137  and held at a partial locking position where locking projections  39  (only those for the small female terminals  127 S are shown in  FIG. 22 ) are before the cavities  28 L,  28 S. The female terminals  127 L,  126 S then are inserted into the corresponding cavities  128 L,  127 S and are pushed sufficiently to be locked by the locks  136 L,  136 S. The retainer  138  then is pushed a full locking position. As a result, the locking projections  39  enter the corresponding cavities  128 L,  127 S and engage the female terminals  127 L,  126 S in the cavities  128 L,  127 S. Thus, the female terminals  127 L,  126 S are locked so as not to come out. 
   The slider  40  is made e.g. of a synthetic resin similar to the female housing  20 , but has a color different from the color of the female housing  20 . As shown in  FIGS. 28 and 29 , the slider  40  has a gate or U-shape with two slidable portions  41  connected by a coupling plate  42 . The slider  40  is mounted laterally (from either left or right side) by inserting both slidable plates  41  into the upper and lower insertion paths  126  of the female housing  20 . 
   Each slidable plate  41  has a cam groove  44 . The cam groove  44  extends from the leading end of the front edge of the slidable plate  41  substantially to a longitudinal center, and inclines gradually toward the rear edge. An entrance  45  of the cam groove  44  is open substantially at a right angle to the front edge of the slidable plate  41  and is continuous with the starting end  44 A. 
   Follower pins  17  stand at substantially widthwise middle positions near the front edges of the upper and lower bottom surfaces of the small receptacle  12 , as shown in  FIGS. 21 to 23 , and are engageable with the corresponding cam grooves  44 . Further, an introducing hole  47  is formed substantially at a widthwise middle of a front plate  126 A of each of the upper and lower insertion paths  126  of the female housing  20 , as shown in  FIG. 24 , for permitting entry of the corresponding follower pin  17 . 
   A grip  50  is formed on the outer surface of the base end of each slidable plate  41  of the slider  40  to manipulate, insert and withdraw the slider  40 . On the other hand, escape grooves  152  are formed at the opposite left and right ends of the upper and lower covers of the female housing  20 , as shown in  FIG. 25 , for receiving the grips  50  of the slider  40 . 
   Each slidable plate  41  of the slider  40  has a fastening piece  154  at a position corresponding to a substantially longitudinal middle portion of the cam groove  44  and displaced toward the rear edge, as shown in  FIGS. 28 and 29 . The fastening pieces  154  cantilever towards the base ends of the slidable plates  41  and are resiliently deformable. Protrusions  155  are formed on the outer surfaces of the projecting ends thereof. Each slidable plate  41  also has a locking piece  156  at a position substantially in the middle between the fastening piece  154  and the coupling plate  42  and displaced toward the rear edge. The locking piece  156  cantilevers towards the base end of the slidable plate  41  and is resiliently deformable. A locking claw  157  is formed on the outer surface of the extending end of the locking piece  156 . A surface of the protrusion  155  of each fastening piece  154  at its projecting end is at an angle and preferably substantially normal to an extending direction ED of the fastening piece  154 . The locking claw  157  of each locking piece  156  has a slanted surface  157 A that is slightly oblique to a plane normal to the extending direction ED of the fastening piece  154 , as shown in  FIG. 30 . 
   A long groove  60  is formed substantially in a longitudinal middle part of each cover  125  of the female housing  20  along the rear edge thereof, as shown in  FIG. 21 . The protrusions  155  of the fastening pieces  154  are fit movably into the long grooves  60 . Opposite ends of the long grooves  60  are closed at the outer surfaces, and locking holes  61  are formed in the inner surfaces of the closed portions, as shown in  FIGS. 27 and 30 , for receiving the protrusions  155  of the corresponding fastening pieces  154  and the locking claws  157  of the locking pieces  156 . Opposite left and right surfaces of each locking hole  61  are formed into locking surfaces  61 A that are arranged substantially normal to the pushing direction PD and the extension direction ED. Moderately rounded sloped surfaces  61 B face the locking surfaces  61 A. 
   The slidable plates  41  of the slider  40  are inserted into the insertion paths  126  of the female housing  20 , for example, from the left side of  FIG. 21  and the protrusions  155  of the fastening pieces  154  drop into the locking holes  61  at the left ends of the long grooves  60  in  FIG. 21  to hold the slider  40  at a retracted position. At this retracted position, the entrances  45  of the cam grooves  44  align with the introducing holes  47  of the female housing  20 . 
   The slider  40  is pushed in the pushing direction PD to an advanced position where the coupling plate  42  contacts the left surface of the female housing  20 . At this advanced position, the locking claws  157  of the locking pieces  156  fit into and lock in the locking holes  61 , as shown in  FIG. 25 . The slanted surfaces  157 A of the locking claws  157  thus engage the locking surfaces  61 A of the locking holes  61  to form a semi-locking construction. The locking pieces  156  will deform resiliently and disengage from the locking holes  61  if a force of a specified intensity or higher acts on the slider  40  in a direction toward the retracted position and opposite to the pushing direction PD. 
   Since the same functions as above are displayed in the case that the slider  40  is mounted from the right side of the female housing  20 , and no repeated description is given on this case. In other words, the side from which the slider  40  is more easily insertable can be selected depending on an installed position of the connector. 
   Each of the upper and lower covers  125  of the female housing  20  has a confirmation window  65  for visually and/or automatically confirming whether the slider  40  is at the retracted position. Specifically, each confirmation window  65  has a substantially rectangular shape and is at a position slightly before the long groove  60  and in the longitudinal center of the cover  125 , as shown in  FIG. 21 . 
   A part  167  of the back-side edge of a starting end  44 A of the cam groove  44  of each slidable plate  41  is in substantially the entire corresponding confirmation window  65  only when the slider  40  is at the retracted position. When the slider  40  is before the retracted position, a part of each cam groove  44  is located in the corresponding confirmation window  65 . This also applies when the slider  40  is mounted from the right side. 
   Each cam groove  44  has a starting end  44 A that is substantially continuous with the entrance  45 . More particularly, the starting end  44 A is slightly steep and inclined at a bigger angle with respect to the pushing direction PD than more rearward parts of the cam groove  44 . A substantially straight portion  44 B is substantially continuous with the starting end  44 A. The straight portion  44 B has a more moderate inclination with respect to the pushing direction PD than the starting end  44 A and is inclined toward the rear side with respect to the connecting direction CD as it extends towards its back end. The straight portion  44 B has a substantially constant inclination and makes up a large part of the cam groove  44 . The rear end of the straight portion  44 B is bent to define a peak  44 C. A returning portion  44 D is continuous with the peak  44 C. The returning portion  44 D is between the peak  44 C and a terminus end  44 E, as shown in  FIG. 33 . The returning portion  44 D is considerably shorter than the straight portion  44 B and is located very close to the terminus end  44 E. Additionally, the returning portion  44 D is inclined toward the front side and in a direction substantially opposite to the inclination of the straight portion  44 B with respect to the connecting direction CD as it extends toward the terminus end  44 E. More specifically, as shown in  FIG. 31 , an angle of inclination a of the front edge of the returning portion  44 D is in a range from about 10° to about 5°, and preferably at about 7° to a pushing direction PD of the slider  40 . 
   The female terminals  127 L,  126 S are inserted into the corresponding cavities  128 L,  127 S of the female housing  20  from behind, and the rear parts of the cavities  128 L,  128 S are closed by the rubber plugs  134 . The female terminals  127 L,  127 S are locked doubly by the retainer  138 . 
   The slider  40  also is mounted into the female housing  20  in advance. The slidable plates  41  of the slider  40  are inserted into the insertion paths  126 , for example, from the left side of the female housing  20  and the slider  40  is pushed in the pushing direction PD to the advanced position at in a single stroke. The locking claws  157  of the locking pieces  156  are fit resiliently into the locking holes  61 , as shown in  FIGS. 25 and 10 , to hold the slider  40  at the advanced position. 
   The female housing  20  preferably is transported to a site of a connecting operation with the male housing  10  while the slider  40  is at the advanced position. The slider  40  is returned to the retracted position prior to the connection of the housings  10 ,  20 . More particularly, the upper and lower grips  50  of the slider  40  are pulled. As a result, the locking pieces  156  are guided by the slanted surfaces  157 A of the locking claws  157  and deform inward to come out of the locking holes  61  and to cancel the locked state. Accordingly, the slider  40  can be pulled. In the meantime, the fastening pieces  154  are returned substantially along the long grooves  60 . The slider  40  stops being pulled when the protrusions  155  engage into the locking holes  61 . Thus, the slider  40  is held at the retracted position shown in  FIG. 21 . 
   The male housing  10  can be moved along the connecting direction CD and into the larger receptacle  22  of the female housing  20 , as indicated by an arrow in  FIG. 21 , after the slider  40  has been returned to the proper retracted position. The follower pins  17  of the male housing  10  then enter the entrances  45  of the cam grooves  44  through the introducing holes  47 . The male housing  10  is pushed further and the follower pins  17  push the back edges (upper edges in  FIG. 31 ) of the starting ends  44 A of the cam groove  44 , as shown in  FIG. 31 . Thus, the slider  40  is moved by a specified distance along the inclination of the starting ends  44 A toward the advanced position. As a result, the follower pins  17  enter the cam grooves  44  and are caught by the front edges of the starting ends  44 A, to prevent disengagement of the male housing  10 . 
   The slider  40  next is pushed in the pushing direction PD toward the advanced position. Thus, the follower pins  17  are displaced along the starting ends  44 A and the straight portions  44 B due mostly to the front edges of the cam grooves  44  pushing the follower pins  17 . As a result, the male housing  10  is pulled gradually into the female housing  20 . The outer peripheral surface of the seal ring  23  slides closely in sliding contact with the inner peripheral surface of the small receptacle  12  and undergoes a resilient deformation as the housings  10 ,  20  are connected more deeply. Thus, the inner space of the two housings  10 ,  20  is sealed airtight and an inner pressure gradually increases to create biasing forces acting on the housings  10 ,  20  in separating directions SD as the housings  10 ,  20  are brought closer to each other. As a result, resistance on the slider  40  increases. 
   The respective male terminals  14 L,  14 S are inserted into the terminal connecting portions  131  of the mating female terminals  127 L,  127 S when the housings  10 ,  20  are brought closer together and the resilient contact pieces are brought resiliently into sliding contact with the male terminals  14 L,  14 S. The two housings  10 ,  20  are connected most deeply when the follower pins  17  reach the peaks  44 C of the cam grooves  44 . At this time, the inner pressure in the housings  10 ,  20  reaches its maximum and, therefore, the resistance on the slider  40  also reaches its maximum (see phantom line in  FIGS. 32 and 33 ). 
   The slider  40  is pushed further in this state. Thus, the follower pins  17  enter the returning portions  44 D beyond the peaks  44 C and are displaced toward the terminus ends  44 E in the returning portions  44 D. Consequently, the two housings  10 ,  20  are displaced gradually in separating directions SD. At this time, the biasing forces caused by the inner pressure between the two housings  10 ,  20  push the housings  10 ,  20  in separating directions SD and pull the slider  40 . As a result, the resistance on the slider  40  suddenly decreases and the slider  40  is pushed to the advanced position with the addition of an inertial force. The locking claws  157  of the locking pieces  156  are fit into the locking holes  61  to lock the slider  40  in the advanced position (see  FIG. 30 ). In this way, the follower pins  17  reach the terminus ends  44 E of the cam grooves  44 , as shown in  FIG. 33 , and the male and female housings  10 ,  20  are connected properly as shown in  FIGS. 34 and 35 . 
   Forces on the housings  10 ,  20  in separating directions SD are created, for example, by pulling forces on the wires  133 , the resiliency of the sealing members between the housings  10 ,  20  and/or the inner pressure of the two housings  10 ,  20 . These forces that act on the two housings  10 ,  20  in separating directions SD at a final stage of the connection of the two housings  10 ,  20  pull the slider  40 , and thus prevent the slider  40  from stopping at an intermediate position without reaching the terminus end  44 E. 
   Forces could act on the two housings  10 ,  20  in separating directions SD, for example, due to the wires  133  pulled backward or an increase in the inner pressure due to a temperature change with the two housings  10 ,  20  are connected. These forces cause the follower pins  17  to be pushed against the edges of the cam grooves  44  near the terminus ends  44 E. Thus, there is no likelihood that the follower pins  17  push the slider  40  back toward the retracted position to separate the housings  10 ,  20 . 
   The grips  50  of the slider  40  can be pulled in the state shown in  FIGS. 34 and 35  to separate the two housings  10 ,  20 . As a result, the locking pieces  156  deform resiliently to cancel the locked state, and the slider  40  can be pulled further. The follower pins  17  then move toward the peaks  44 C in the returning portions  44 D of the cam grooves  44 , and the two housings  10 ,  20  are displaced once in directions to deepen the connection. The follower pins  17  then move beyond the peaks  44 C and the male housing  10  is pushed gradually out in a direction SD to separate from the female housing  20  mainly because the back edges of the cam grooves  44  push the follower pins  17 . The follower pins  17  are returned to the entrances  45  of the cam grooves  44  when the slider  40  is pulled back to the retracted position. Thus, the male housing  10  can be separated from the female housing  20  while causing the follower pins  17  to exit forward through the introducing holes  47 . 
   As described above, the returning portions  44 D are near the terminus ends  44 E of the cam grooves  44 . Thus, forces on the housings  10 ,  20  in separating directions SD at the final stage of the connection of the two housings  10 ,  20  pull the slider  40  toward the advanced position. Therefore, the slider  40  will not stop at an intermediate position, and the two housings  10 ,  20  are prevented from being left only partly connected. 
   The two housings  10 ,  20  could be pulled in separating directions SD while being properly connected. However, such pulling only results in the follower pins  17  being pressed against the edges of the cam grooves  44  near the terminus ends  44 E. Thus, the two housings  10 ,  20  are prevented from being separated by pushing back the slider  40 . 
   The watertight connector described above results in an inner pressure that increases as the two housings  10 ,  20  are more deeply connected. Thus, the slider  40  is pulled with a strong force when the follower pins  17  enter the returning portions  44 D at the final stage of the connection. Therefore, the slider  40  is prevented from stopping at an intermediate position. 
   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. 
   The slider may be mounted into the male housing. 
   The present invention is also applicable to nonwatertight connectors. 
   Even though the invention has been described with reference to a slider being substantially linearly movable along the pushing direction, it should be understood that the invention is also applicable to connectors in which the cam action is displayed by a different movable member such as a rotatable or pivotable lever, a movable member movable substantially along a non-linear path, etc.