Patent Publication Number: US-2011070764-A1

Title: Locking cap for a connector-fastening screw

Description:
FIELD 
     The present invention relates to locking of a connector and more specifically relates to locking of a screw for fastening a connector. 
     BACKGROUND 
     Many connectors capable of readily attaching a cable to equipment, or removing a cable from equipment, are used for connection of electrical cables, fiber optic cables, and the like to electronic equipment. Among such connectors are connectors that fasten together with a mating member by use of a screw for reliable maintenance of the state of joining together with the equipment. A structure that uses a screw for fastening has the advantage of increased joining-together strength in comparison to other means, such as a structure utilizing a locking piece capable of elastic deformation and constructed from plastic and the like. However, there is a chance of the screw becoming loose due to vibration and the like occurring in the environment of use of the connector such that the connector falls out. 
     Various types of attempts have been made to prevent a connector fastened by a fastening screw from falling out due to vibration or shock. For example, Patent Citation No. 1 (U.S. Pat. No. 7,033,202) mentions “a cable end connector includes an insulating housing with a number of contacts retained therein, a first cover receiving the insulating housing therein, a second cover assembled to the first cover, a pair of fastening members, and a pair of spring members.” According to the connector mentioned in this citation, “if the screw connection between the cable end connector and the complementary connector becomes loosened due to vibration/physical shock during use, the spring member automatically resumes to its original shape to motivate the fastening member to move rearwardly until the stop section abuts against the rear ends of the recessed sections. Thus, the loose connection between the cable end connector and the complementary connector can be easily detected, whereby the user can immediately secure the cable end connector with the complementary connector to ensure a reliable connection therebetween.” 
     SUMMARY 
     For all connectors, without regard as to whether or not there is concern for vibration in the environment of use of the connector, to contain a locking means for a fastening screw is disadvantageous from the standpoints of cost and the like, and there is concern that size of the resultant connector would become excessively large. Moreover, determination of the need for the locking means beforehand is often difficult. Furthermore, when a locking means becomes needed (due to reasons such as change of installation location of the equipment and the like) for a connector connected to equipment, there is a need to replace the existing connector with a connector equipped with a locking means. Also, when there is a need for this locking means to respond in some type of deformational or mechanical manner to the mating member, application of a connector equipped with a locking means to existing equipment becomes more difficult. 
     Moreover, even when a locking means has been provided, there may be the possibility of occurrence of looseness of the fastening screw by the imparting of vibration and the like that is greater than anticipated. In such cases when looseness of the fastening screw can not be ascertained from the exterior, looseness of the fastening screw may not be detected until the connector falls out and the electrical connection is interrupted. 
     Thus according to one aspect of the present invention, a locking cap for a connector-fastening screw is provided that comprises: a main body having a receiving hole, a contact part disposed on the main body for control of rotation of the main body, and an indicator part disposed on the main body capable of providing visual recognition of rotation of the main body. 
     According to an aspect of the present invention, the locking cap is capable of being appended to the fastening screw of the connector. Thus the occurrence of looseness of the fastening screw can be made visible due to rotation of the position of the indicator part due to looseness of the fastening screw. 
     A locking cap according to one embodiment of the present invention is affixed to a handling part of a fastening screw provided on an electrical connector, fiber optic connector, and the like which is fixed to another connector by the fastening screw. A receiving hole is provided in the locking cap for receiving the handling part, the inner face of the locking cap engages with the outer peripheral face of the handling part, and the locking cap is capable of rotation in a unified manner with the fastening screw. The locking cap has a contact part, and at a certain time as the fastening screw loosens and rotates together with the locking cap in a unified manner, the contact part contacts the connector, and further rotation is suppressed. It becomes possible by this means to prevent loosening of the fastening screw. Moreover, since the indicator part of the locking cap also rotates due to rotation of the fastening screw, detection of the occurrence of looseness of the fastening screw is possible even when loosening of the fastening screw itself is not visible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective drawing showing the first embodiment of the present invention. 
         FIG. 2  is a partial planar cross-sectional diagram showing condition of use of the first embodiment of the present invention. 
         FIG. 3   a  is a front view of the locking cap mounted on the connector, according to the first embodiment of the present invention. 
         FIG. 3   b  is a front view of the locking cap in contact with the connector, according to the first embodiment of the present invention. 
         FIG. 4  is a perspective drawing showing the second embodiment of the present invention. 
         FIG. 5   a  is a planar drawing of the locking cap, according to the third embodiment of the present invention. 
         FIG. 5   b  is a planar drawing of the locking cap, according to a variant example of the third embodiment of the present invention. 
         FIG. 5   c  is a planar drawing of the locking cap, according to another variant example of the third embodiment of the present invention. 
         FIG. 5   d  is a planar drawing of the locking cap, according to another variant example of the third embodiment of the present invention. 
         FIG. 6   a  is a front view showing the locking cap mounted on a connector, according to the third embodiment of the present invention. 
         FIG. 6   b  is a front view showing the locking cap in contact with a connector, according to the third embodiment of the present invention. 
         FIG. 7   a  is a perspective drawing showing a locking cap, according to the fourth embodiment of the present invention. 
         FIG. 7   b  is a perspective drawing showing a locking cap, according to the variant example of the fourth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF REFERENCE NUMBERS 
     
         
           1  . . . locking cap 
           10  . . . main body 
           12  . . . side face 
           13  . . . corner part 
           14  . . . front end face 
           16  . . . rear end face 
           18  . . . receiving hole 
           20  . . . inner face 
           22  . . . protrusion 
           24  . . . side wall 
           26  . . . edge part 
           28  . . . exterior face 
           30  . . . lower face 
           32  . . . front face 
           34  connection part 
           35   a  . . . first part 
           35   b  . . . second part 
           36  . . . ring-shaped part 
           40  . . . cable connector 
           41  . . . joining face 
           42  . . . housing 
           44 ,  44   a  . . . side face 
           46  . . . fastening screw 
           48  . . . handling part 
           48   a  . . . outer peripheral face 
           49  . . . screw part 
           50  . . . cable 
           54  . . . receptacle 
           56  . . . female screw 
       
    
     DETAILED DESCRIPTION 
     The present invention is explained below using various embodiments.  FIG. 1  is a perspective view that shows a locking cap according to one embodiment of the present invention.  FIG. 2  is a planar view showing the state of the locking cap of the present invention during use on a cable connector. A locking cap  1  comprises a main body  10 , a protrusion  22  protruding from the main body  10 , and a connection part  34  connecting together two main bodies  10 ,  10 . The connection part  34  is made flexible enough so that the main body  10  can rotate with respect to the axial direction of the main body  10  to a degree needed as a locking cap of present invention, for example, one rotation or less. The cable connector  40  fits together with a receptacle  54  and is fastened to the receptacle  54  using a fastening screw  46 . The locking cap  1  of the present invention is mounted on a handling part  48  of the fastening screw  46 . 
     The main body  10  is an approximately rectangular body provided with a front end face  14  at one tip in the length-wise direction thereof and provided with a rear end face  16  at the opposite tip. The front end face  14  and the rear end face  16  are each roughly formed as a respective rectangle. The main body  10  is further provided with a plurality of side faces  12  which intersect with both of the front end face  14  and the rear end face  16 , where the long sides of the side faces  12  are substantially aligned with the length-wise direction of the main body  10 . A corner part  13  is present between adjacent side faces  12  and  12  such that the two adjacent side faces are smoothly interconnected. Size of the main body  10  can be set such that a slight gap occurs between the cable connector  40  and the main body  10  when the locking cap  1  is mounted on the cable connector  40 . In this manner, rotation of the main body  10  is permitted when the fastening screw  46  is loose, and visual detection of the occurrence of looseness becomes possible. In this manner, looseness of the fastening screw  46  appears as rotational movement of the main body  10 , and slight looseness of the fastening screw  46  can be readily recognized visually. 
     A receiving hole  18  is provided as a circular through-hole in the front end face  14  of the main body  10 . The receiving hole  18  is demarcated by an inner face  20 . The receiving hole  18  is disposed at the approximate center of the front end face  14 , and interior diameter of the receiving hole  18  has roughly the same size as outer diameter of the handling part  48  of the fastening screw  46 . The inner face  20  at least partially engages with an outer peripheral face  48   a  of the handling part  48  of the connector-fastening screw  46 , and thus the main body  10  and the connector-fastening screw  46  become able to rotate as a single unit. Thus the inner face  20  can have a shape which is complimentary with the shape of the handling part  48 . It is also possible to provide one or a plurality of protrusions on the inner face  20 , or to provide one or a plurality of grooves extending in the axial direction of the main body  10 , such that the handling part  48  is more securely engaged with the main body  10 . 
     The protrusion  22  is a tabular shaped part that projects forward from the front end face  14 . Protrusion  22  is provided with a wide exterior face  28  that faces outwardly, a lower face  30  disposed opposite to the exterior face  28 , a pair of side walls  24  and  24  having long sides extending in the length-wise direction of the main body  10  and intersect with the exterior face  28  and the lower face  30 , and a front face  32  disposed at the distal tip of the protrusion  22  and having a face which is roughly parallel with the front end face  14  and intersects with the exterior face  28 , the lower face  30 , and the two side walls  24  and  24 . Plurality of edge parts  26  are provided between the side walls  24  and the lower face  30  of the protrusion  22 , as well as between the side walls  24  and the exterior face  28 . The edge part  26  is where two faces of the protrusion  22  intersects each other and forms a line. According to the present embodiment, the exterior face  28  of the protrusion  22  is flush with one side face  12  of the main body  10 , and the side walls  24  and  24  and the inner face  30  are each recessed relative to their corresponding side faces  12 , i.e., the sides faces facing the same direction. When the fastening screw  46  has loosened to an extent such that rotation occurs, part of the protrusion  22  contacts the cable connector  40 , and the protrusion  22  is able to display a function that restricts further loosening of the fastening screw  46 . The presence or absence of looseness of the fastening screw  46  can also be readily visualized by checking for change of the position of the protrusion  22  relative to the cable connector  40 . Furthermore, the protrusion  22  can be formed such that the exterior face  28  is disposed to the exterior of the side face  12 . Shape of the protrusion  22  is not limited to the above mentioned tabular shape, and the protrusion can be formed as a polygonal column, circular column, or hemispherical protrusion. The degree of protrusion of the protrusion  22  can be set arbitrarily as long as the degree of protrusion makes possible contact between the protrusion  22  and the cable connector  40  when the locking cap  1  is attached to the cable connector  40  and the main body  10  is rotated. Moreover, although width of the exterior face  28  was smaller than width of the side face  12  according to the present embodiment, width of the exterior face  28  can also be made the same as width of the side face  12 . Although protrusion  22  is disposed such that the width-direction center of the exterior face  28  roughly coincides with the width-direction center of the side face  12 , disposal is possible such that these centers do not coincide. That is to say, it is possible to dispose the protrusion  22  at a position displaced from the width-direction center of the side face  12 . 
     The connection part  34  is a part that connects together two main bodies  10  and  10  and extends from the rear end face  16  of a first main body  10  to the rear end face  16  of the other main body  10 . The connection part  34  makes possible handling of the main bodies  10  and  10  as a single unit. The connection part  34  is flexible enough to allow rotation of the main body  10 . The connection part  34  is provided with first parts  35   a  extending from the main body  10  in the length-wise direction of the main body  10  and a second part  35   b  connected to the pair of first parts  35   a . The first part  35   a  has a ribbon shape and has a length-direction cross-sectional shape that is roughly rectangular. The second part  35   b  has a roughly square cross-sectional shape in the length-wise direction thereof. The connection part  34  can have an arbitrary shape that differs from the illustrated ribbon shape. The connection part  34 , rather than extending from the rear end face  16  of the main body  10 , can also extend from one of the side faces  12  of the main body  10 . The connection part  34  may be provided by integration with the main body  10  or can be provided as a separate component. 
     At roughly the center of the second part  35   b  of the connection part  34 , a ring-shaped part  36  is provided that has an interior diameter of a size such that the cable can be passed therethrough. The ring-shaped part  36 , at one point of the outer peripheral face thereof, is connected to the second part  35   b . Due to insertion beforehand of the cable through the ring-shaped part  36 , loss of the detached locking cap  1  can be prevented. A split of a width sufficiently smaller than the inner diameter of the ring-shaped part  36  may also be provided in the ring-shaped part  36 . When this type of split is provided, due to insertion of the cable through the split, the locking cap  1  can be readily mounted on the cable. Furthermore, since the ring-shaped part  36  also has a certain degree of elasticity, the ring-shaped part  36  elastically returns to its original shape after insertion of the cable through the split, and falling off of the locking cap  1  from the cable can be prevented. 
     The locking cap  1  can be produced by known methods from an arbitrary material. For example, plastic, metal material, and the like can be used for production by injection molding and the like. Production from plastic is preferred from the standpoints of cost and mass production ability, and a thermoplastic type plastic can be used such as polypropylene, polyethylene, and the like. By use of such a relatively soft plastic, deformation of the inner face  20  to match the shape of the handling part  48  is possible during mounting of the main body  10  on the handling part  48 , and engagement between the main body  10  and the handling part  48  can be further strengthened. 
     The applicable connector for the present invention will next be explained. The cable connector  40  is attached to a tip of the cable  50 , and the cable connector  40  and the receptacle  54  are joined together at the joining face  41  thereof. The cable connector  40  has a pair of housings  42  and  42 , and a plurality of core wires of the cable is separated within the housing  42 . A non-illustrated interface part is provided on the front tip of the cable connector  40 , and typically a plurality of contacts is disposed within the interface part. Each of the plurality of core wires of the cable is electrically connected to a respective contact among the plurality of contacts. The receptacle  54  is also provided with an interface part that has a plurality of contacts, and the interface part is normally the complement of that of the cable connector  40 . The contacts of the receptacle  54  are electrically connected to a non-illustrated circuit board and the like. The cable connector  40  and the receptacle  54  are electrically mutually connected through the contacts. The cable connector  40  has a fastening screw  46  for fixing to the receptacle  54  at both side part of the cable connector  40 , and locking cap  1  is mounted on each of the fastening screws  46  and  46 . 
     A screw part  49  is provided on the front tip of the fastening screw  46 , and a handling part  48  is provided on the opposite tip. A screw thread  49   a  is provided on the outer peripheral face of the screw part  49 . The screw part  49  provided on the tip of the fastening screw  46  screws into a female screw  56  provided in the receptacle  54  such that the cable connector  40  is fixed to the receptacle  54 . A plurality of grooves are provided extending in the axial direction of the fastening screw  46  on the outer peripheral face of the handling part  48  to prevent slipping of the fingers when the operator rotates the fastening screw. Moreover, in addition to grooves in the axial direction, the fastening screw  46  may have grooves extending in the circumferential direction and crossing the axial-direction grooves. 
     Operation of the locking cap  1  of the present embodiment will be explained while referring to  FIGS. 3   a  and  3 B.  FIGS. 3   a  and  3   b  is a front view of the cable connector  40 , as seen from the joining face thereof, with the locking cap  1  mounted thereon. When the cable connector  40  is engaged with the receptacle  54 , these members are fastened together by the fastening screw  46 . Then each main body  10  of the locking cap  1  is mounted on the respective fastening screw  46 . At this time, the protrusion  22  is positioned toward the side face  44  of the cable connector  40 , and a gap is opened up ( FIG. 3   a ) between the protrusion  22  and the side face  44  such that the fastening screw  46  is able to rotate in the loosening direction thereof. When the fastening screw becomes loose due to vibration applied to the connector, the protrusion  22  contacts the housing  42  of the cable connector  40  ( FIG. 3   b ). According to the present embodiment, the edge part  26  between the side wall  24  and the lower face  30  of the protrusion  22  contacts the cable connector  40  and operates as the contact part. Due to engagement of the locking cap  1  with the fastening screw  46  in a unified manner, when the locking cap  1  and the housing  42  touch together, further loosening of the fastening screw  46  is restricted. Furthermore, the contact part is not limited to the edge part  26 , and due to shape and the like of the housing  42  of the cable connector  40 , the side wall  24  of the protrusion  22  can contact the cable connector  40  such that the function of the contact part can be performed. Rotation of the fastening screw  46  also can be controlled by contact between the cable connector  40  and a part of the locking cap  1  other than the protrusion. Moreover, since position of the protrusion  22  relative to the cable connector  40  changes due to rotation of the locking cap  1 , the protrusion  22  functions as an indicator part, and occurrence/non-occurrence of looseness of the fastening screw  46  can be determined by looking at the position of the protrusion  22 . The fastening screw  46  and the female screw  56  are screwed together by multiple screw threads, and thus several rotations of the fastening screw  46  are normally required for the fastening screw  46  to disengage from the female screw  56 . The locking cap  1  normally restricts rotation of the fastening screw  46  to less than one rotation. 
     Thus when looseness of the fastening screw  46  is seen using the indicator part, the fastening screw  46  screwing together with the female screw  56  is still maintained. In this manner, occurrence of looseness of the locking cap  1  can be detected prior to disengagement of the fastening screw  46  from the female screw  56 . It is also possible to consider non-engaging rotation of the fastening screw  46  relative to the locking cap  1  when the force causing rotation of the fastening screw  46  due to vibration applied to the connector is unexpectedly large and such torque overcomes the engagement strength between the handling part  48  and the inner face  20 . Due to the ability of the locking cap  1  to rotate relative to the cable connector  40 , even in cases when the loosening of the fastening screw  46  can not be stopped, the occurrence of loosening of the fastening screw  46  can be detected based on rotation of the locking cap  1 . Thus appropriate measures become possible, such as retightening of the fastening screw  46  by the operator prior to the occurrence of disengagement of the connector. Furthermore, the mounting direction of the locking cap  1  is not limited to the above mentioned direction, and any direction is permissible as long as rotation is possible in the direction of loosening of the fastening screw  46 . Furthermore, although this embodiment describes a method of use that allows a certain degree of looseness of the fastening screw  46  prior to display of the loosening stoppage function by the locking cap  1 , use is also possible of a locking cap  1  that does not allow any loosening of the fastening screw  46 . That is to say, the locking cap  1  can be attached to the fastening screw  46  in a state that causes contact between the contact part (protrusion  22 ) and the cable connector  40  such that rotation of the fastening screw  46  in the loosening direction is not possible. 
     The indication means may be disposed by a known means on one side face  12  of the main body  10  or on the exterior face  28  of the protrusion  22  in order to further facilitate determination of the looseness of the fastening screw  46 . A symbol (such as an arrow and the like), number, letter, and the like can be used as the indication means, and this indication means can be provided by a known method such as printing, transfer by engraving on a mold, and the like. When the indication means is provided in this manner, it is easy to understand which part of the locking cap  1  to refer to in order to determine the presence or absence of loosening of the fastening screw  46 . 
       FIG. 4  shows a locking cap  101  according to a second embodiment of the present invention. The locking cap  101  is provided with a main body  110  and a connection part  134 . The present embodiment differs from the first embodiment in that the protrusion  122  is placed on one side face  112  of the main body  110 . Width of the protrusion  122  is narrower than width of the side face  112 , and the protrusion  122  extends on one of the side faces  112  from the front end face  114  toward the rear end face  116 . When the locking cap  101  is mounted on the cable connector  40  by accepting the handling part  48  in a receiving hole  118  disposed on a front end face  114 , attachment is possible, for example, with the protrusion  122  oriented so as to not contact the housing  42 . When loosening of the fastening screw  46  occurs due to vibration, the locking cap  101  rotates together with the fastening screw  46 , and by this means, relative position of the protrusion  122  changes relative to the cable connector  40 . Due to this rotation of the protrusion  122 , the occurrence of loosening of the fastening screw  46  can be seen. Moreover, further rotation of the fastening screw  46  can be restricted by contact of the side wall  124  or the edge part  126  with the housing  42 . In this manner, the protrusion part  122  is able to function as the contact part also for the present embodiment in which the protrusion  122  protrudes in the lateral direction. Moreover, the protrusion  122  part can function also as the indicator part in the above described manner Depending on shape or size of the cable connector, control of rotation of the fastening screw  46  is also possible by contact between the cable connector  40  and a part other than the protrusion. Furthermore, although width of the exterior face  128  is smaller than width of the side face  112  according to the structure of the present embodiment, formation is also possible such that the exterior face  128  has the same width as the side face  112 . Although the protrusion  122  is disposed such that the width-direction center of the exterior face  128  roughly coincides with the width-direction center of the side face  112 , a structure is also possible where these centers do not coincide. That is to say, the protrusion  122  can be disposed at a position that is displaced from the width-direction center of the side face  112 . Moreover, the protrusion  122  may extend from the front end face  114  of the main body  110  to the rear end face  116 . Alternatively, the protrusion  122  may extend from the rear end face  116  toward the front end face  114  over a length that is shorter than length of the main body  110 . Alternatively, the protrusion  122  may extend along only a central part of the length-wise direction of the main body  110 . 
       FIG. 5   a  shows a locking cap according to a third embodiment of the present invention. According to the present embodiment, a recess part  223  is provided in part of the main body  210 . The recess part  223  has a first surface  223   a  that is recessed from one of the side faces  212  and has a second surface  223   b  that is recessed from the front end face  214 . The recess part  223  surface or the edge part  226  functions as the contact part, and the recess part  223  can also function as the indicator part. An indication means can also be provided for the present embodiment, for example, by providing an indication means on the first surface  223   a  of one side face  212 . The locking cap having this type of shape can be used in cases such as when there is a desire to suppress rotation of the locking cap using the side face  44   a  of the housing  42  opposite to the fastening screw  46 . Meanwhile, it is possible to form the recess part  223  such that a part of the receiving hole  218  opens in the second surface  223   b.    
     Operation of the main body  210  of the present embodiment will be explained while referring to  FIGS. 6   a  and  6   b .  FIGS. 6   a  and  6   b  is a front view of the part of attachment of the fastening screw  46  of the cable connector  40  as seen from the joining face side of the cable connector  40 . The first surface  223   a  of the recess part  223  is oriented so as to oppose the side face  44   a  of the cable connector  40  when the main body  210  is mounted on the handling part  48  of the fastening screw  46 . At this time, the first surface  223   a  can be aligned roughly parallel to the side face  44   a . When looseness of the fastening screw  46  occurs due to the application of vibration to the cable connector  40 , the main body  210  rotates together with the fastening screw  46 . When the main body  210  rotates, the edge part  226  of the recess part  223  contacts the side face  44   a , and further rotation is restricted ( FIG. 6   b ). Displacement of the recess part  223  from its initial position relative to the side face  44   a  can be readily seen in this state, and the operator is able to readily discover looseness of the fastening screw  46 . Furthermore, orientation of the main body  210  during attachment to the fastening screw  46  is not limited to the above mentioned orientation, and any orientation is permissible as long as rotation is possible in the direction of loosening of the fastening screw  46 . Moreover, using the shape of the housing  42  of the cable connector  40 , the first surface  223   a  can function as the contact part by contacting the cable connector  40 . 
     Variant examples of the third embodiment are presented in  FIG. 5   b  through  FIG. 5   d . Within  FIG. 5   b , the recess part  323  is formed on a main body  310  as one bowed face  323   a  having a concave shape that intersects three sides faces  312  and the front end face  314 . The bowed face  323   a  or an edge part  326  functions as the contact part, and the recess part  323  can also function as the indicator part. An indication means can also be provided for the present embodiment, for example, by providing an indication means on the bowed face  323   a . It is possible to form the recess part  323  such that a part of the receiving hole  318  opens in the bowed face  323   a . According to  FIG. 5   c , a recess part  423  is formed from a plane (tilted face)  423   a  that is tilted with respect to the axial direction of a main body  410  and that intersects the front end face  414  and three side faces  412 . The tilted face  423   a  or an edge part  426  functions as the contact part, and the recess part  423  can also function as the indicator part. An indication means can also be provided for the present embodiment, for example, by providing an indication means on the tilted face  423   a . It is possible to form the recess part  423  such that a part of the receiving hole  418  opens in the tilted face  423   a . In  FIG. 5   d , a main body  510  is shown with a recess part  523  having a large size and having a receiving hole  518  as an aperture in the tilted face  523   a  of the recess part  523 . The tilted face  523   a  intersects three sides faces  512  and the front end face  514 . The tilted face  523   a  or an edge part  526  functions as the contact part, and the recess part  523  can also function as the indicator part. An indication means can also be provided for the present embodiment, for example, by providing an indication means on the tilted face  523   a.    
     Within  FIGS. 7   a  and  7   b , a locking cap  601  is shown according to a fourth embodiment of the present invention. The locking cap  601  is provided with an approximately rectangular main body  610  and a connection part  634 . The locking cap  601  differs from the above mentioned embodiments in that the main body  610  is not equipped with a protrusion or recess part. When the locking cap  601  is mounted on the cable connector by accepting the handling part  48  in a receiving hole  618  disposed on a front end face  614 , the locking cap  601  can be mounted on the handling part such that one of the side faces  612  is pointed toward the cable connector. According to the present embodiment, one of the side faces  612  or a corner part  613  performs the function of the contact part, and when the fastening screw  46  becomes loose, looseness of the fastening screw  46  is prevented by contact between the cable connector  40  and the one side face  612  or the one corner part  613 . One or a plurality of side faces  612  of the main body  610  is capable of functioning as the indicator part. An indicator means, such as those described previously, can be further provided on the side face  612  that functions as the indicator part. 
     As a variant example of the fourth embodiment,  FIG. 7   b , for example, shows a locking cap  701  provided with a main body  710  having a front end face  714  having trapezoidal shape and a connection part  734 . According to the present variant example, when the side face  712   a  corresponding to the truncated side of the trapezoidal shape is disposed facing the cable connector  40  or the side face  712   b  corresponding to the long side of the trapezoidal shape is made to face the cable connector, the degree of permissible looseness (degree of rotation) of the fastening screw can be varied according to shape of the cable connector. When the side face  712   a  is made to face the cable connector  40 , in comparison to the side face  712   b  facing the cable connector  40 , the degree of permissible looseness of the fastening screw increases, and the occurrence of looseness becomes more readily visible. Moreover, rotation of the main body  710  can be readily recognized since the main body  710  has clear directionality. 
     The locking cap of the present invention was explained according to the above listed explanations of the embodiments. However, the present invention is not limited to the above mentioned embodiments, and further variations are possible, such as those described below. Multiple combinations of the below mentioned variations are possible, and combination with any of the above mentioned embodiments is also possible. 
     The receiving hole provided in the main body was described for the case of provision of a receiving hole that was co-axial with the length-direction axis of the main body. However, the receiving hole can be disposed eccentrically from the location of the length-direction axis of the main body with goals such as adjustment of the gap between the fastening screw and the housing, adjustment of the permissible degree of rotation of the fastening screw, and the like. 
     Any shape can be used as the shape of the main body. In addition to the roughly rectangular body shape, this shape, for example, can be a circular column shape or a polygonal column shape such as a hexagonal column and the like. 
     Shape of the receiving hole, in the case of use of a shape that is complementary with the shape of the handling part, can be any shape that corresponds to the shape of the handling part. Moreover, even when the shape of the receiving hole is not complementary with the shape of the handling part, any shape can be used for the receiving hole as long as relative rotation is not allowed between the handling part and the main body. For example, use of a shape is possible that contacts the handling part at part of the inner face. Furthermore, rather than a through-aperture for the receiving hole, a structure is also permissible that uses a recess having a bottom face. Although the receiving hole was a hole having a uniform diameter according to the above mentioned embodiments, a conically shaped hole, for example, is also permissible that has a large diameter at the front end face side and has a small diameter at the rear end face side. By use of this shape, mounting of the main body on the handling part is facilitated, and use becomes possible on a plurality of cable connectors having handling parts of different sizes.